[Mlir-commits] [mlir] ebf521e - Separate the Registration from Loading dialects in the Context

Mehdi Amini llvmlistbot at llvm.org
Fri Aug 14 02:43:06 PDT 2020


Author: Mehdi Amini
Date: 2020-08-14T09:40:27Z
New Revision: ebf521e78483693e5cc9ba4ad3298f0397923624

URL: https://github.com/llvm/llvm-project/commit/ebf521e78483693e5cc9ba4ad3298f0397923624
DIFF: https://github.com/llvm/llvm-project/commit/ebf521e78483693e5cc9ba4ad3298f0397923624.diff

LOG: Separate the Registration from Loading dialects in the Context

This changes the behavior of constructing MLIRContext to no longer load globally registered dialects on construction. Instead Dialects are only loaded explicitly on demand:
- the Parser is lazily loading Dialects in the context as it encounters them during parsing. This is the only purpose for registering dialects and not load them in the context.
- Passes are expected to declare the dialects they will create entity from (Operations, Attributes, or Types), and the PassManager is loading Dialects into the Context when starting a pipeline.

This changes simplifies the configuration of the registration: a compiler only need to load the dialect for the IR it will emit, and the optimizer is self-contained and load the required Dialects. For example in the Toy tutorial, the compiler only needs to load the Toy dialect in the Context, all the others (linalg, affine, std, LLVM, ...) are automatically loaded depending on the optimization pipeline enabled.

Added: 
    

Modified: 
    flang/unittests/Lower/OpenMPLoweringTest.cpp
    mlir/examples/standalone/standalone-opt/standalone-opt.cpp
    mlir/examples/toy/Ch2/toyc.cpp
    mlir/examples/toy/Ch3/toyc.cpp
    mlir/examples/toy/Ch4/toyc.cpp
    mlir/examples/toy/Ch5/mlir/LowerToAffineLoops.cpp
    mlir/examples/toy/Ch5/toyc.cpp
    mlir/examples/toy/Ch6/mlir/LowerToAffineLoops.cpp
    mlir/examples/toy/Ch6/mlir/LowerToLLVM.cpp
    mlir/examples/toy/Ch6/toyc.cpp
    mlir/examples/toy/Ch7/mlir/LowerToAffineLoops.cpp
    mlir/examples/toy/Ch7/mlir/LowerToLLVM.cpp
    mlir/examples/toy/Ch7/toyc.cpp
    mlir/include/mlir-c/IR.h
    mlir/include/mlir/Conversion/Passes.td
    mlir/include/mlir/Dialect/Affine/Passes.td
    mlir/include/mlir/Dialect/LLVMIR/LLVMDialect.h
    mlir/include/mlir/Dialect/LLVMIR/LLVMOpBase.td
    mlir/include/mlir/Dialect/LLVMIR/NVVMDialect.h
    mlir/include/mlir/Dialect/LLVMIR/NVVMOps.td
    mlir/include/mlir/Dialect/LLVMIR/ROCDLDialect.h
    mlir/include/mlir/Dialect/LLVMIR/ROCDLOps.td
    mlir/include/mlir/Dialect/Linalg/Passes.td
    mlir/include/mlir/Dialect/SCF/Passes.td
    mlir/include/mlir/IR/Dialect.h
    mlir/include/mlir/IR/FunctionSupport.h
    mlir/include/mlir/IR/MLIRContext.h
    mlir/include/mlir/IR/OpBase.td
    mlir/include/mlir/InitAllDialects.h
    mlir/include/mlir/Pass/Pass.h
    mlir/include/mlir/Pass/PassBase.td
    mlir/include/mlir/Pass/PassManager.h
    mlir/include/mlir/Support/MlirOptMain.h
    mlir/include/mlir/TableGen/Dialect.h
    mlir/include/mlir/TableGen/Pass.h
    mlir/include/mlir/Transforms/Passes.td
    mlir/lib/CAPI/IR/IR.cpp
    mlir/lib/Conversion/GPUToVulkan/ConvertGPULaunchFuncToVulkanLaunchFunc.cpp
    mlir/lib/Conversion/LinalgToLLVM/LinalgToLLVM.cpp
    mlir/lib/Conversion/PassDetail.h
    mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp
    mlir/lib/Conversion/StandardToSPIRV/LegalizeStandardForSPIRV.cpp
    mlir/lib/Dialect/Affine/Transforms/PassDetail.h
    mlir/lib/Dialect/Linalg/IR/LinalgOps.cpp
    mlir/lib/Dialect/Linalg/Transforms/PassDetail.h
    mlir/lib/Dialect/SCF/Transforms/PassDetail.h
    mlir/lib/Dialect/SDBM/SDBMExpr.cpp
    mlir/lib/ExecutionEngine/JitRunner.cpp
    mlir/lib/IR/Dialect.cpp
    mlir/lib/IR/MLIRContext.cpp
    mlir/lib/IR/Operation.cpp
    mlir/lib/IR/Verifier.cpp
    mlir/lib/Parser/AttributeParser.cpp
    mlir/lib/Parser/DialectSymbolParser.cpp
    mlir/lib/Parser/Parser.cpp
    mlir/lib/Pass/Pass.cpp
    mlir/lib/Pass/PassDetail.h
    mlir/lib/Support/MlirOptMain.cpp
    mlir/lib/TableGen/Dialect.cpp
    mlir/lib/TableGen/Pass.cpp
    mlir/lib/Target/LLVMIR/ConvertFromLLVMIR.cpp
    mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
    mlir/lib/Transforms/PassDetail.h
    mlir/test/CAPI/ir.c
    mlir/test/EDSC/builder-api-test.cpp
    mlir/test/SDBM/sdbm-api-test.cpp
    mlir/test/lib/Dialect/Affine/TestVectorizationUtils.cpp
    mlir/test/lib/Dialect/SPIRV/TestAvailability.cpp
    mlir/test/lib/Dialect/Test/TestPatterns.cpp
    mlir/test/lib/Transforms/TestAllReduceLowering.cpp
    mlir/test/lib/Transforms/TestBufferPlacement.cpp
    mlir/test/lib/Transforms/TestGpuMemoryPromotion.cpp
    mlir/test/lib/Transforms/TestLinalgHoisting.cpp
    mlir/test/lib/Transforms/TestLinalgTransforms.cpp
    mlir/test/lib/Transforms/TestVectorTransforms.cpp
    mlir/test/mlir-opt/commandline.mlir
    mlir/tools/mlir-linalg-ods-gen/mlir-linalg-ods-gen.cpp
    mlir/tools/mlir-opt/mlir-opt.cpp
    mlir/tools/mlir-tblgen/DialectGen.cpp
    mlir/tools/mlir-tblgen/PassGen.cpp
    mlir/tools/mlir-translate/mlir-translate.cpp
    mlir/unittests/Dialect/Quant/QuantizationUtilsTest.cpp
    mlir/unittests/Dialect/SPIRV/DeserializationTest.cpp
    mlir/unittests/Dialect/SPIRV/SerializationTest.cpp
    mlir/unittests/IR/AttributeTest.cpp
    mlir/unittests/IR/DialectTest.cpp
    mlir/unittests/IR/OperationSupportTest.cpp
    mlir/unittests/Pass/AnalysisManagerTest.cpp
    mlir/unittests/SDBM/SDBMTest.cpp
    mlir/unittests/TableGen/OpBuildGen.cpp
    mlir/unittests/TableGen/StructsGenTest.cpp

Removed: 
    


################################################################################
diff  --git a/flang/unittests/Lower/OpenMPLoweringTest.cpp b/flang/unittests/Lower/OpenMPLoweringTest.cpp
index ad6fe739d16b..4c23845584f6 100644
--- a/flang/unittests/Lower/OpenMPLoweringTest.cpp
+++ b/flang/unittests/Lower/OpenMPLoweringTest.cpp
@@ -15,8 +15,7 @@
 class OpenMPLoweringTest : public testing::Test {
 protected:
   void SetUp() override {
-    mlir::registerDialect<mlir::omp::OpenMPDialect>();
-    mlir::registerAllDialects(&ctx);
+    ctx.getOrLoadDialect<mlir::omp::OpenMPDialect>();
     mlirOpBuilder.reset(new mlir::OpBuilder(&ctx));
   }
 

diff  --git a/mlir/examples/standalone/standalone-opt/standalone-opt.cpp b/mlir/examples/standalone/standalone-opt/standalone-opt.cpp
index 5c99058693c3..eb624b3e8954 100644
--- a/mlir/examples/standalone/standalone-opt/standalone-opt.cpp
+++ b/mlir/examples/standalone/standalone-opt/standalone-opt.cpp
@@ -76,7 +76,7 @@ int main(int argc, char **argv) {
   if (showDialects) {
     mlir::MLIRContext context;
     llvm::outs() << "Registered Dialects:\n";
-    for (mlir::Dialect *dialect : context.getRegisteredDialects()) {
+    for (mlir::Dialect *dialect : context.getLoadedDialects()) {
       llvm::outs() << dialect->getNamespace() << "\n";
     }
     return 0;

diff  --git a/mlir/examples/toy/Ch2/toyc.cpp b/mlir/examples/toy/Ch2/toyc.cpp
index d0880ce0971b..99232d8f24a4 100644
--- a/mlir/examples/toy/Ch2/toyc.cpp
+++ b/mlir/examples/toy/Ch2/toyc.cpp
@@ -68,10 +68,9 @@ std::unique_ptr<toy::ModuleAST> parseInputFile(llvm::StringRef filename) {
 }
 
 int dumpMLIR() {
-  // Register our Dialect with MLIR.
-  mlir::registerDialect<mlir::toy::ToyDialect>();
-
-  mlir::MLIRContext context;
+  mlir::MLIRContext context(/*loadAllDialects=*/false);
+  // Load our Dialect in this MLIR Context.
+  context.getOrLoadDialect<mlir::toy::ToyDialect>();
 
   // Handle '.toy' input to the compiler.
   if (inputType != InputType::MLIR &&

diff  --git a/mlir/examples/toy/Ch3/toyc.cpp b/mlir/examples/toy/Ch3/toyc.cpp
index f9d5631719e8..d0430ce16e54 100644
--- a/mlir/examples/toy/Ch3/toyc.cpp
+++ b/mlir/examples/toy/Ch3/toyc.cpp
@@ -102,10 +102,10 @@ int loadMLIR(llvm::SourceMgr &sourceMgr, mlir::MLIRContext &context,
 }
 
 int dumpMLIR() {
-  // Register our Dialect with MLIR.
-  mlir::registerDialect<mlir::toy::ToyDialect>();
+  mlir::MLIRContext context(/*loadAllDialects=*/false);
+  // Load our Dialect in this MLIR Context.
+  context.getOrLoadDialect<mlir::toy::ToyDialect>();
 
-  mlir::MLIRContext context;
   mlir::OwningModuleRef module;
   llvm::SourceMgr sourceMgr;
   mlir::SourceMgrDiagnosticHandler sourceMgrHandler(sourceMgr, &context);

diff  --git a/mlir/examples/toy/Ch4/toyc.cpp b/mlir/examples/toy/Ch4/toyc.cpp
index e11f35c5f7e1..9f95887d2707 100644
--- a/mlir/examples/toy/Ch4/toyc.cpp
+++ b/mlir/examples/toy/Ch4/toyc.cpp
@@ -103,10 +103,10 @@ int loadMLIR(llvm::SourceMgr &sourceMgr, mlir::MLIRContext &context,
 }
 
 int dumpMLIR() {
-  // Register our Dialect with MLIR.
-  mlir::registerDialect<mlir::toy::ToyDialect>();
+  mlir::MLIRContext context(/*loadAllDialects=*/false);
+  // Load our Dialect in this MLIR Context.
+  context.getOrLoadDialect<mlir::toy::ToyDialect>();
 
-  mlir::MLIRContext context;
   mlir::OwningModuleRef module;
   llvm::SourceMgr sourceMgr;
   mlir::SourceMgrDiagnosticHandler sourceMgrHandler(sourceMgr, &context);

diff  --git a/mlir/examples/toy/Ch5/mlir/LowerToAffineLoops.cpp b/mlir/examples/toy/Ch5/mlir/LowerToAffineLoops.cpp
index 3097681ea3fa..1077fc9cecea 100644
--- a/mlir/examples/toy/Ch5/mlir/LowerToAffineLoops.cpp
+++ b/mlir/examples/toy/Ch5/mlir/LowerToAffineLoops.cpp
@@ -256,6 +256,10 @@ struct TransposeOpLowering : public ConversionPattern {
 namespace {
 struct ToyToAffineLoweringPass
     : public PassWrapper<ToyToAffineLoweringPass, FunctionPass> {
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<AffineDialect>();
+    registry.insert<StandardOpsDialect>();
+  }
   void runOnFunction() final;
 };
 } // end anonymous namespace.

diff  --git a/mlir/examples/toy/Ch5/toyc.cpp b/mlir/examples/toy/Ch5/toyc.cpp
index ed0496957093..16faac02fc60 100644
--- a/mlir/examples/toy/Ch5/toyc.cpp
+++ b/mlir/examples/toy/Ch5/toyc.cpp
@@ -106,10 +106,10 @@ int loadMLIR(llvm::SourceMgr &sourceMgr, mlir::MLIRContext &context,
 }
 
 int dumpMLIR() {
-  // Register our Dialect with MLIR.
-  mlir::registerDialect<mlir::toy::ToyDialect>();
+  mlir::MLIRContext context(/*loadAllDialects=*/false);
+  // Load our Dialect in this MLIR Context.
+  context.getOrLoadDialect<mlir::toy::ToyDialect>();
 
-  mlir::MLIRContext context;
   mlir::OwningModuleRef module;
   llvm::SourceMgr sourceMgr;
   mlir::SourceMgrDiagnosticHandler sourceMgrHandler(sourceMgr, &context);

diff  --git a/mlir/examples/toy/Ch6/mlir/LowerToAffineLoops.cpp b/mlir/examples/toy/Ch6/mlir/LowerToAffineLoops.cpp
index cac3415f48d6..9ff9eb495b24 100644
--- a/mlir/examples/toy/Ch6/mlir/LowerToAffineLoops.cpp
+++ b/mlir/examples/toy/Ch6/mlir/LowerToAffineLoops.cpp
@@ -255,6 +255,10 @@ struct TransposeOpLowering : public ConversionPattern {
 namespace {
 struct ToyToAffineLoweringPass
     : public PassWrapper<ToyToAffineLoweringPass, FunctionPass> {
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<AffineDialect>();
+    registry.insert<StandardOpsDialect>();
+  }
   void runOnFunction() final;
 };
 } // end anonymous namespace.

diff  --git a/mlir/examples/toy/Ch6/mlir/LowerToLLVM.cpp b/mlir/examples/toy/Ch6/mlir/LowerToLLVM.cpp
index 74b32dc0ca11..8020fb309165 100644
--- a/mlir/examples/toy/Ch6/mlir/LowerToLLVM.cpp
+++ b/mlir/examples/toy/Ch6/mlir/LowerToLLVM.cpp
@@ -159,6 +159,10 @@ class PrintOpLowering : public ConversionPattern {
 namespace {
 struct ToyToLLVMLoweringPass
     : public PassWrapper<ToyToLLVMLoweringPass, OperationPass<ModuleOp>> {
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<LLVM::LLVMDialect>();
+    registry.insert<scf::SCFDialect>();
+  }
   void runOnOperation() final;
 };
 } // end anonymous namespace

diff  --git a/mlir/examples/toy/Ch6/toyc.cpp b/mlir/examples/toy/Ch6/toyc.cpp
index bdcdf1af7ea8..9504a38b8784 100644
--- a/mlir/examples/toy/Ch6/toyc.cpp
+++ b/mlir/examples/toy/Ch6/toyc.cpp
@@ -255,10 +255,10 @@ int main(int argc, char **argv) {
 
   // If we aren't dumping the AST, then we are compiling with/to MLIR.
 
-  // Register our Dialect with MLIR.
-  mlir::registerDialect<mlir::toy::ToyDialect>();
+  mlir::MLIRContext context(/*loadAllDialects=*/false);
+  // Load our Dialect in this MLIR Context.
+  context.getOrLoadDialect<mlir::toy::ToyDialect>();
 
-  mlir::MLIRContext context;
   mlir::OwningModuleRef module;
   if (int error = loadAndProcessMLIR(context, module))
     return error;

diff  --git a/mlir/examples/toy/Ch7/mlir/LowerToAffineLoops.cpp b/mlir/examples/toy/Ch7/mlir/LowerToAffineLoops.cpp
index 3097681ea3fa..1077fc9cecea 100644
--- a/mlir/examples/toy/Ch7/mlir/LowerToAffineLoops.cpp
+++ b/mlir/examples/toy/Ch7/mlir/LowerToAffineLoops.cpp
@@ -256,6 +256,10 @@ struct TransposeOpLowering : public ConversionPattern {
 namespace {
 struct ToyToAffineLoweringPass
     : public PassWrapper<ToyToAffineLoweringPass, FunctionPass> {
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<AffineDialect>();
+    registry.insert<StandardOpsDialect>();
+  }
   void runOnFunction() final;
 };
 } // end anonymous namespace.

diff  --git a/mlir/examples/toy/Ch7/mlir/LowerToLLVM.cpp b/mlir/examples/toy/Ch7/mlir/LowerToLLVM.cpp
index 74b32dc0ca11..8020fb309165 100644
--- a/mlir/examples/toy/Ch7/mlir/LowerToLLVM.cpp
+++ b/mlir/examples/toy/Ch7/mlir/LowerToLLVM.cpp
@@ -159,6 +159,10 @@ class PrintOpLowering : public ConversionPattern {
 namespace {
 struct ToyToLLVMLoweringPass
     : public PassWrapper<ToyToLLVMLoweringPass, OperationPass<ModuleOp>> {
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<LLVM::LLVMDialect>();
+    registry.insert<scf::SCFDialect>();
+  }
   void runOnOperation() final;
 };
 } // end anonymous namespace

diff  --git a/mlir/examples/toy/Ch7/toyc.cpp b/mlir/examples/toy/Ch7/toyc.cpp
index c1cc207a406c..cb3b455dc7ec 100644
--- a/mlir/examples/toy/Ch7/toyc.cpp
+++ b/mlir/examples/toy/Ch7/toyc.cpp
@@ -256,10 +256,10 @@ int main(int argc, char **argv) {
 
   // If we aren't dumping the AST, then we are compiling with/to MLIR.
 
-  // Register our Dialect with MLIR.
-  mlir::registerDialect<mlir::toy::ToyDialect>();
+  mlir::MLIRContext context(/*loadAllDialects=*/false);
+  // Load our Dialect in this MLIR Context.
+  context.getOrLoadDialect<mlir::toy::ToyDialect>();
 
-  mlir::MLIRContext context;
   mlir::OwningModuleRef module;
   if (int error = loadAndProcessMLIR(context, module))
     return error;

diff  --git a/mlir/include/mlir-c/IR.h b/mlir/include/mlir-c/IR.h
index 6b5be2d0195b..f9ec4d132056 100644
--- a/mlir/include/mlir-c/IR.h
+++ b/mlir/include/mlir-c/IR.h
@@ -90,6 +90,12 @@ MlirContext mlirContextCreate();
 /** Takes an MLIR context owned by the caller and destroys it. */
 void mlirContextDestroy(MlirContext context);
 
+/** Load all the globally registered dialects in the provided context.
+ *  TODO: remove the concept of globally registered dialect by exposing the
+ *  DialectRegistry.
+ */
+void mlirContextLoadAllDialects(MlirContext context);
+
 /*============================================================================*/
 /* Location API.                                                              */
 /*============================================================================*/

diff  --git a/mlir/include/mlir/Conversion/Passes.td b/mlir/include/mlir/Conversion/Passes.td
index 4d4fe064a6bc..0c40bb3bbfb6 100644
--- a/mlir/include/mlir/Conversion/Passes.td
+++ b/mlir/include/mlir/Conversion/Passes.td
@@ -66,6 +66,11 @@ def ConvertAffineToStandard : Pass<"lower-affine"> {
         `affine.apply`.
   }];
   let constructor = "mlir::createLowerAffinePass()";
+  let dependentDialects = [
+    "scf::SCFDialect",
+    "StandardOpsDialect",
+    "vector::VectorDialect"
+  ];
 }
 
 //===----------------------------------------------------------------------===//
@@ -76,6 +81,7 @@ def ConvertAVX512ToLLVM : Pass<"convert-avx512-to-llvm", "ModuleOp"> {
   let summary = "Convert the operations from the avx512 dialect into the LLVM "
                 "dialect";
   let constructor = "mlir::createConvertAVX512ToLLVMPass()";
+  let dependentDialects = ["LLVM::LLVMDialect", "LLVM::LLVMAVX512Dialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -98,6 +104,7 @@ def GpuToLLVMConversionPass : Pass<"gpu-to-llvm", "ModuleOp"> {
 def ConvertGpuOpsToNVVMOps : Pass<"convert-gpu-to-nvvm", "gpu::GPUModuleOp"> {
   let summary = "Generate NVVM operations for gpu operations";
   let constructor = "mlir::createLowerGpuOpsToNVVMOpsPass()";
+  let dependentDialects = ["NVVM::NVVMDialect"];
   let options = [
     Option<"indexBitwidth", "index-bitwidth", "unsigned",
            /*default=kDeriveIndexBitwidthFromDataLayout*/"0",
@@ -112,6 +119,7 @@ def ConvertGpuOpsToNVVMOps : Pass<"convert-gpu-to-nvvm", "gpu::GPUModuleOp"> {
 def ConvertGpuOpsToROCDLOps : Pass<"convert-gpu-to-rocdl", "gpu::GPUModuleOp"> {
   let summary = "Generate ROCDL operations for gpu operations";
   let constructor = "mlir::createLowerGpuOpsToROCDLOpsPass()";
+  let dependentDialects = ["ROCDL::ROCDLDialect"];
   let options = [
     Option<"indexBitwidth", "index-bitwidth", "unsigned",
            /*default=kDeriveIndexBitwidthFromDataLayout*/"0",
@@ -126,6 +134,7 @@ def ConvertGpuOpsToROCDLOps : Pass<"convert-gpu-to-rocdl", "gpu::GPUModuleOp"> {
 def ConvertGPUToSPIRV : Pass<"convert-gpu-to-spirv", "ModuleOp"> {
   let summary = "Convert GPU dialect to SPIR-V dialect";
   let constructor = "mlir::createConvertGPUToSPIRVPass()";
+  let dependentDialects = ["spirv::SPIRVDialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -136,6 +145,7 @@ def ConvertGpuLaunchFuncToVulkanLaunchFunc
     : Pass<"convert-gpu-launch-to-vulkan-launch", "ModuleOp"> {
   let summary = "Convert gpu.launch_func to vulkanLaunch external call";
   let constructor = "mlir::createConvertGpuLaunchFuncToVulkanLaunchFuncPass()";
+  let dependentDialects = ["spirv::SPIRVDialect"];
 }
 
 def ConvertVulkanLaunchFuncToVulkanCalls
@@ -143,6 +153,7 @@ def ConvertVulkanLaunchFuncToVulkanCalls
   let summary = "Convert vulkanLaunch external call to Vulkan runtime external "
                 "calls";
   let constructor = "mlir::createConvertVulkanLaunchFuncToVulkanCallsPass()";
+  let dependentDialects = ["LLVM::LLVMDialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -153,6 +164,7 @@ def ConvertLinalgToLLVM : Pass<"convert-linalg-to-llvm", "ModuleOp"> {
   let summary = "Convert the operations from the linalg dialect into the LLVM "
                 "dialect";
   let constructor = "mlir::createConvertLinalgToLLVMPass()";
+  let dependentDialects = ["scf::SCFDialect", "LLVM::LLVMDialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -163,6 +175,7 @@ def ConvertLinalgToStandard : Pass<"convert-linalg-to-std", "ModuleOp"> {
   let summary = "Convert the operations from the linalg dialect into the "
                 "Standard dialect";
   let constructor = "mlir::createConvertLinalgToStandardPass()";
+  let dependentDialects = ["StandardOpsDialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -172,6 +185,7 @@ def ConvertLinalgToStandard : Pass<"convert-linalg-to-std", "ModuleOp"> {
 def ConvertLinalgToSPIRV : Pass<"convert-linalg-to-spirv", "ModuleOp"> {
   let summary = "Convert Linalg ops to SPIR-V ops";
   let constructor = "mlir::createLinalgToSPIRVPass()";
+  let dependentDialects = ["spirv::SPIRVDialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -182,6 +196,7 @@ def SCFToStandard : Pass<"convert-scf-to-std"> {
   let summary = "Convert SCF dialect to Standard dialect, replacing structured"
                 " control flow with a CFG";
   let constructor = "mlir::createLowerToCFGPass()";
+  let dependentDialects = ["StandardOpsDialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -191,6 +206,7 @@ def SCFToStandard : Pass<"convert-scf-to-std"> {
 def ConvertAffineForToGPU : FunctionPass<"convert-affine-for-to-gpu"> {
   let summary = "Convert top-level AffineFor Ops to GPU kernels";
   let constructor = "mlir::createAffineForToGPUPass()";
+  let dependentDialects = ["gpu::GPUDialect"];
   let options = [
     Option<"numBlockDims", "gpu-block-dims", "unsigned", /*default=*/"1u",
            "Number of GPU block dimensions for mapping">,
@@ -202,6 +218,7 @@ def ConvertAffineForToGPU : FunctionPass<"convert-affine-for-to-gpu"> {
 def ConvertParallelLoopToGpu : Pass<"convert-parallel-loops-to-gpu"> {
   let summary = "Convert mapped scf.parallel ops to gpu launch operations";
   let constructor = "mlir::createParallelLoopToGpuPass()";
+  let dependentDialects = ["AffineDialect", "gpu::GPUDialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -212,6 +229,7 @@ def ConvertShapeToStandard : Pass<"convert-shape-to-std", "ModuleOp"> {
   let summary = "Convert operations from the shape dialect into the standard "
                 "dialect";
   let constructor = "mlir::createConvertShapeToStandardPass()";
+  let dependentDialects = ["StandardOpsDialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -221,6 +239,7 @@ def ConvertShapeToStandard : Pass<"convert-shape-to-std", "ModuleOp"> {
 def ConvertShapeToSCF : FunctionPass<"convert-shape-to-scf"> {
   let summary = "Convert operations from the shape dialect to the SCF dialect";
   let constructor = "mlir::createConvertShapeToSCFPass()";
+  let dependentDialects = ["scf::SCFDialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -230,6 +249,7 @@ def ConvertShapeToSCF : FunctionPass<"convert-shape-to-scf"> {
 def ConvertSPIRVToLLVM : Pass<"convert-spirv-to-llvm", "ModuleOp"> {
   let summary = "Convert SPIR-V dialect to LLVM dialect";
   let constructor = "mlir::createConvertSPIRVToLLVMPass()";
+  let dependentDialects = ["LLVM::LLVMDialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -264,6 +284,7 @@ def ConvertStandardToLLVM : Pass<"convert-std-to-llvm", "ModuleOp"> {
     LLVM IR types.
   }];
   let constructor = "mlir::createLowerToLLVMPass()";
+  let dependentDialects = ["LLVM::LLVMDialect"];
   let options = [
     Option<"useAlignedAlloc", "use-aligned-alloc", "bool", /*default=*/"false",
            "Use aligned_alloc in place of malloc for heap allocations">,
@@ -287,11 +308,13 @@ def ConvertStandardToLLVM : Pass<"convert-std-to-llvm", "ModuleOp"> {
 def LegalizeStandardForSPIRV : Pass<"legalize-std-for-spirv"> {
   let summary = "Legalize standard ops for SPIR-V lowering";
   let constructor = "mlir::createLegalizeStdOpsForSPIRVLoweringPass()";
+  let dependentDialects = ["spirv::SPIRVDialect"];
 }
 
 def ConvertStandardToSPIRV : Pass<"convert-std-to-spirv", "ModuleOp"> {
   let summary = "Convert Standard Ops to SPIR-V dialect";
   let constructor = "mlir::createConvertStandardToSPIRVPass()";
+  let dependentDialects = ["spirv::SPIRVDialect"];
 }
 
 //===----------------------------------------------------------------------===//
@@ -302,6 +325,7 @@ def ConvertVectorToSCF : FunctionPass<"convert-vector-to-scf"> {
   let summary = "Lower the operations from the vector dialect into the SCF "
                 "dialect";
   let constructor = "mlir::createConvertVectorToSCFPass()";
+  let dependentDialects = ["AffineDialect", "scf::SCFDialect"];
   let options = [
     Option<"fullUnroll", "full-unroll", "bool", /*default=*/"false",
            "Perform full unrolling when converting vector transfers to SCF">,
@@ -316,6 +340,7 @@ def ConvertVectorToLLVM : Pass<"convert-vector-to-llvm", "ModuleOp"> {
   let summary = "Lower the operations from the vector dialect into the LLVM "
                 "dialect";
   let constructor = "mlir::createConvertVectorToLLVMPass()";
+  let dependentDialects = ["LLVM::LLVMDialect"];
   let options = [
     Option<"reassociateFPReductions", "reassociate-fp-reductions",
            "bool", /*default=*/"false",
@@ -331,6 +356,7 @@ def ConvertVectorToROCDL : Pass<"convert-vector-to-rocdl", "ModuleOp"> {
   let summary = "Lower the operations from the vector dialect into the ROCDL "
                 "dialect";
   let constructor = "mlir::createConvertVectorToROCDLPass()";
+  let dependentDialects = ["ROCDL::ROCDLDialect"];
 }
 
 #endif // MLIR_CONVERSION_PASSES

diff  --git a/mlir/include/mlir/Dialect/Affine/Passes.td b/mlir/include/mlir/Dialect/Affine/Passes.td
index 810640058155..f43fabd19aae 100644
--- a/mlir/include/mlir/Dialect/Affine/Passes.td
+++ b/mlir/include/mlir/Dialect/Affine/Passes.td
@@ -94,6 +94,7 @@ def AffineLoopUnrollAndJam : FunctionPass<"affine-loop-unroll-jam"> {
 def AffineVectorize : FunctionPass<"affine-super-vectorize"> {
   let summary = "Vectorize to a target independent n-D vector abstraction";
   let constructor = "mlir::createSuperVectorizePass()";
+  let dependentDialects = ["vector::VectorDialect"];
   let options = [
     ListOption<"vectorSizes", "virtual-vector-size", "int64_t",
                "Specify an n-D virtual vector size for vectorization",

diff  --git a/mlir/include/mlir/Dialect/LLVMIR/LLVMDialect.h b/mlir/include/mlir/Dialect/LLVMIR/LLVMDialect.h
index 04700f0aa17d..2f465f07a97e 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/LLVMDialect.h
+++ b/mlir/include/mlir/Dialect/LLVMIR/LLVMDialect.h
@@ -15,6 +15,7 @@
 #define MLIR_DIALECT_LLVMIR_LLVMDIALECT_H_
 
 #include "mlir/Dialect/LLVMIR/LLVMTypes.h"
+#include "mlir/Dialect/OpenMP/OpenMPDialect.h"
 #include "mlir/IR/Dialect.h"
 #include "mlir/IR/Function.h"
 #include "mlir/IR/OpDefinition.h"

diff  --git a/mlir/include/mlir/Dialect/LLVMIR/LLVMOpBase.td b/mlir/include/mlir/Dialect/LLVMIR/LLVMOpBase.td
index d21f5bc0b49b..2617a2da9d0f 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/LLVMOpBase.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/LLVMOpBase.td
@@ -19,6 +19,11 @@ include "mlir/IR/OpBase.td"
 def LLVM_Dialect : Dialect {
   let name = "llvm";
   let cppNamespace = "LLVM";
+
+  /// FIXME: at the moment this is a dependency of the translation to LLVM IR,
+  /// not really one of this dialect per-se.
+  let dependentDialects = [ "omp::OpenMPDialect" ];
+
   let hasRegionArgAttrVerify = 1;
   let extraClassDeclaration = [{
     ~LLVMDialect();

diff  --git a/mlir/include/mlir/Dialect/LLVMIR/NVVMDialect.h b/mlir/include/mlir/Dialect/LLVMIR/NVVMDialect.h
index 86d437c9b561..9cc5314bdb90 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/NVVMDialect.h
+++ b/mlir/include/mlir/Dialect/LLVMIR/NVVMDialect.h
@@ -14,6 +14,7 @@
 #ifndef MLIR_DIALECT_LLVMIR_NVVMDIALECT_H_
 #define MLIR_DIALECT_LLVMIR_NVVMDIALECT_H_
 
+#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
 #include "mlir/IR/Dialect.h"
 #include "mlir/IR/OpDefinition.h"
 #include "mlir/Interfaces/SideEffectInterfaces.h"

diff  --git a/mlir/include/mlir/Dialect/LLVMIR/NVVMOps.td b/mlir/include/mlir/Dialect/LLVMIR/NVVMOps.td
index 5f022e32b801..0e5bc16f4568 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/NVVMOps.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/NVVMOps.td
@@ -23,6 +23,7 @@ include "mlir/Interfaces/SideEffectInterfaces.td"
 def NVVM_Dialect : Dialect {
   let name = "nvvm";
   let cppNamespace = "NVVM";
+  let dependentDialects = [ "LLVM::LLVMDialect" ];
 }
 
 //===----------------------------------------------------------------------===//

diff  --git a/mlir/include/mlir/Dialect/LLVMIR/ROCDLDialect.h b/mlir/include/mlir/Dialect/LLVMIR/ROCDLDialect.h
index bf761c357f90..eb40373c3f11 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/ROCDLDialect.h
+++ b/mlir/include/mlir/Dialect/LLVMIR/ROCDLDialect.h
@@ -22,6 +22,7 @@
 #ifndef MLIR_DIALECT_LLVMIR_ROCDLDIALECT_H_
 #define MLIR_DIALECT_LLVMIR_ROCDLDIALECT_H_
 
+#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
 #include "mlir/IR/Dialect.h"
 #include "mlir/IR/OpDefinition.h"
 #include "mlir/Interfaces/SideEffectInterfaces.h"

diff  --git a/mlir/include/mlir/Dialect/LLVMIR/ROCDLOps.td b/mlir/include/mlir/Dialect/LLVMIR/ROCDLOps.td
index 0cd11690daa8..f9aca5ad7d32 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/ROCDLOps.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/ROCDLOps.td
@@ -23,6 +23,7 @@ include "mlir/Interfaces/SideEffectInterfaces.td"
 def ROCDL_Dialect : Dialect {
   let name = "rocdl";
   let cppNamespace = "ROCDL";
+  let dependentDialects = [ "LLVM::LLVMDialect" ];
 }
 
 //===----------------------------------------------------------------------===//

diff  --git a/mlir/include/mlir/Dialect/Linalg/Passes.td b/mlir/include/mlir/Dialect/Linalg/Passes.td
index 11f12ad30eb6..dcf4b5ec06cb 100644
--- a/mlir/include/mlir/Dialect/Linalg/Passes.td
+++ b/mlir/include/mlir/Dialect/Linalg/Passes.td
@@ -30,17 +30,20 @@ def LinalgFusion : FunctionPass<"linalg-fusion"> {
 def LinalgFusionOfTensorOps : Pass<"linalg-fusion-for-tensor-ops"> {
   let summary = "Fuse operations on RankedTensorType in linalg dialect";
   let constructor = "mlir::createLinalgFusionOfTensorOpsPass()";
+  let dependentDialects = ["AffineDialect"];
 }
 
 def LinalgLowerToAffineLoops : FunctionPass<"convert-linalg-to-affine-loops"> {
   let summary = "Lower the operations from the linalg dialect into affine "
                 "loops";
   let constructor = "mlir::createConvertLinalgToAffineLoopsPass()";
+  let dependentDialects = ["AffineDialect"];
 }
 
 def LinalgLowerToLoops : FunctionPass<"convert-linalg-to-loops"> {
   let summary = "Lower the operations from the linalg dialect into loops";
   let constructor = "mlir::createConvertLinalgToLoopsPass()";
+  let dependentDialects = ["scf::SCFDialect", "AffineDialect"];
 }
 
 def LinalgOnTensorsToBuffers : Pass<"convert-linalg-on-tensors-to-buffers", "ModuleOp"> {
@@ -54,6 +57,7 @@ def LinalgLowerToParallelLoops
   let summary = "Lower the operations from the linalg dialect into parallel "
                 "loops";
   let constructor = "mlir::createConvertLinalgToParallelLoopsPass()";
+  let dependentDialects = ["AffineDialect", "scf::SCFDialect"];
 }
 
 def LinalgPromotion : FunctionPass<"linalg-promote-subviews"> {
@@ -70,6 +74,9 @@ def LinalgPromotion : FunctionPass<"linalg-promote-subviews"> {
 def LinalgTiling : FunctionPass<"linalg-tile"> {
   let summary = "Tile operations in the linalg dialect";
   let constructor = "mlir::createLinalgTilingPass()";
+  let dependentDialects = [
+    "AffineDialect", "scf::SCFDialect"
+  ];
   let options = [
     ListOption<"tileSizes", "linalg-tile-sizes", "int64_t",
                "Test generation of dynamic promoted buffers",
@@ -86,6 +93,7 @@ def LinalgTilingToParallelLoops
                "Test generation of dynamic promoted buffers",
                "llvm::cl::ZeroOrMore, llvm::cl::MiscFlags::CommaSeparated">
   ];
+  let dependentDialects = ["AffineDialect", "scf::SCFDialect"];
 }
 
 #endif // MLIR_DIALECT_LINALG_PASSES

diff  --git a/mlir/include/mlir/Dialect/SCF/Passes.td b/mlir/include/mlir/Dialect/SCF/Passes.td
index 483d0ba7c7be..6f3cf0e12642 100644
--- a/mlir/include/mlir/Dialect/SCF/Passes.td
+++ b/mlir/include/mlir/Dialect/SCF/Passes.td
@@ -36,6 +36,7 @@ def SCFParallelLoopTiling : FunctionPass<"parallel-loop-tiling"> {
                "Factors to tile parallel loops by",
                "llvm::cl::ZeroOrMore, llvm::cl::MiscFlags::CommaSeparated">
   ];
+  let dependentDialects = ["AffineDialect"];
 }
 
 #endif // MLIR_DIALECT_SCF_PASSES

diff  --git a/mlir/include/mlir/IR/Dialect.h b/mlir/include/mlir/IR/Dialect.h
index 4f9e4cb3618b..d00d86db490a 100644
--- a/mlir/include/mlir/IR/Dialect.h
+++ b/mlir/include/mlir/IR/Dialect.h
@@ -16,6 +16,8 @@
 #include "mlir/IR/OperationSupport.h"
 #include "mlir/Support/TypeID.h"
 
+#include <map>
+
 namespace mlir {
 class DialectAsmParser;
 class DialectAsmPrinter;
@@ -23,7 +25,7 @@ class DialectInterface;
 class OpBuilder;
 class Type;
 
-using DialectAllocatorFunction = std::function<void(MLIRContext *)>;
+using DialectAllocatorFunction = std::function<Dialect *(MLIRContext *)>;
 
 /// Dialects are groups of MLIR operations and behavior associated with the
 /// entire group.  For example, hooks into other systems for constant folding,
@@ -212,30 +214,81 @@ class Dialect {
   /// A collection of registered dialect interfaces.
   DenseMap<TypeID, std::unique_ptr<DialectInterface>> registeredInterfaces;
 
-  /// Registers a specific dialect creation function with the global registry.
-  /// Used through the registerDialect template.
-  /// Registrations are deduplicated by dialect TypeID and only the first
-  /// registration will be used.
-  static void
-  registerDialectAllocator(TypeID typeID,
-                           const DialectAllocatorFunction &function);
-  template <typename ConcreteDialect>
   friend void registerDialect();
   friend class MLIRContext;
 };
 
-/// Registers all dialects and hooks from the global registries with the
-/// specified MLIRContext.
+/// The DialectRegistry maps a dialect namespace to a constructor for the
+/// matching dialect.
+/// This allows for decoupling the list of dialects "available" from the
+/// dialects loaded in the Context. The parser in particular will lazily load
+/// dialects in in the Context as operations are encountered.
+class DialectRegistry {
+  using MapTy =
+      std::map<std::string, std::pair<TypeID, DialectAllocatorFunction>>;
+
+public:
+  template <typename ConcreteDialect> void insert() {
+    insert(TypeID::get<ConcreteDialect>(),
+           ConcreteDialect::getDialectNamespace(),
+           static_cast<DialectAllocatorFunction>(([](MLIRContext *ctx) {
+             // Just allocate the dialect, the context
+             // takes ownership of it.
+             return ctx->getOrLoadDialect<ConcreteDialect>();
+           })));
+  }
+
+  /// Add a new dialect constructor to the registry.
+  void insert(TypeID typeID, StringRef name, DialectAllocatorFunction ctor);
+
+  /// Load a dialect for this namespace in the provided context.
+  Dialect *loadByName(StringRef name, MLIRContext *context);
+
+  // Register all dialects available in the current registry with the registry
+  // in the provided context.
+  void appendTo(DialectRegistry &destination) {
+    for (const auto &name_and_registration_it : registry)
+      destination.insert(name_and_registration_it.second.first,
+                         name_and_registration_it.first,
+                         name_and_registration_it.second.second);
+  }
+  // Load all dialects available in the registry in the provided context.
+  void loadAll(MLIRContext *context) {
+    for (const auto &name_and_registration_it : registry)
+      name_and_registration_it.second.second(context);
+  }
+
+  MapTy::const_iterator begin() const { return registry.begin(); }
+  MapTy::const_iterator end() const { return registry.end(); }
+
+private:
+  MapTy registry;
+};
+
+/// Deprecated: this provides a global registry for convenience, while we're
+/// transitionning the registration mechanism to a stateless approach.
+DialectRegistry &getGlobalDialectRegistry();
+
+/// Registers all dialects from the global registries with the
+/// specified MLIRContext. This won't load the dialects in the context,
+/// but only make them available for lazy loading by name.
 /// Note: This method is not thread-safe.
-void registerAllDialects(MLIRContext *context);
+inline void registerAllDialects(MLIRContext *context) {
+  getGlobalDialectRegistry().appendTo(context->getDialectRegistry());
+}
+
+/// Register and return the dialect with the given namespace in the provided
+/// context. Returns nullptr is there is no constructor registered for this
+/// dialect.
+inline Dialect *registerDialect(StringRef name, MLIRContext *context) {
+  return getGlobalDialectRegistry().loadByName(name, context);
+}
 
 /// Utility to register a dialect. Client can register their dialect with the
 /// global registry by calling registerDialect<MyDialect>();
 /// Note: This method is not thread-safe.
 template <typename ConcreteDialect> void registerDialect() {
-  Dialect::registerDialectAllocator(
-      TypeID::get<ConcreteDialect>(),
-      [](MLIRContext *ctx) { ctx->getOrCreateDialect<ConcreteDialect>(); });
+  getGlobalDialectRegistry().insert<ConcreteDialect>();
 }
 
 /// DialectRegistration provides a global initializer that registers a Dialect

diff  --git a/mlir/include/mlir/IR/FunctionSupport.h b/mlir/include/mlir/IR/FunctionSupport.h
index 7e281f393af9..3d467cd4f364 100644
--- a/mlir/include/mlir/IR/FunctionSupport.h
+++ b/mlir/include/mlir/IR/FunctionSupport.h
@@ -428,7 +428,7 @@ LogicalResult FunctionLike<ConcreteType>::verifyTrait(Operation *op) {
       if (!attr.first.strref().contains('.'))
         return funcOp.emitOpError("arguments may only have dialect attributes");
       auto dialectNamePair = attr.first.strref().split('.');
-      if (auto *dialect = ctx->getRegisteredDialect(dialectNamePair.first)) {
+      if (auto *dialect = ctx->getLoadedDialect(dialectNamePair.first)) {
         if (failed(dialect->verifyRegionArgAttribute(op, /*regionIndex=*/0,
                                                      /*argIndex=*/i, attr)))
           return failure();
@@ -444,7 +444,7 @@ LogicalResult FunctionLike<ConcreteType>::verifyTrait(Operation *op) {
       if (!attr.first.strref().contains('.'))
         return funcOp.emitOpError("results may only have dialect attributes");
       auto dialectNamePair = attr.first.strref().split('.');
-      if (auto *dialect = ctx->getRegisteredDialect(dialectNamePair.first)) {
+      if (auto *dialect = ctx->getLoadedDialect(dialectNamePair.first)) {
         if (failed(dialect->verifyRegionResultAttribute(op, /*regionIndex=*/0,
                                                         /*resultIndex=*/i,
                                                         attr)))

diff  --git a/mlir/include/mlir/IR/MLIRContext.h b/mlir/include/mlir/IR/MLIRContext.h
index 0192a8ae06af..d406c300fbbd 100644
--- a/mlir/include/mlir/IR/MLIRContext.h
+++ b/mlir/include/mlir/IR/MLIRContext.h
@@ -19,10 +19,12 @@ namespace mlir {
 class AbstractOperation;
 class DiagnosticEngine;
 class Dialect;
+class DialectRegistry;
 class InFlightDiagnostic;
 class Location;
 class MLIRContextImpl;
 class StorageUniquer;
+DialectRegistry &getGlobalDialectRegistry();
 
 /// MLIRContext is the top-level object for a collection of MLIR modules.  It
 /// holds immortal uniqued objects like types, and the tables used to unique
@@ -34,34 +36,54 @@ class StorageUniquer;
 ///
 class MLIRContext {
 public:
-  explicit MLIRContext();
+  /// Create a new Context.
+  /// The loadAllDialects parameters allows to load all dialects from the global
+  /// registry on Context construction. It is deprecated and will be removed
+  /// soon.
+  explicit MLIRContext(bool loadAllDialects = true);
   ~MLIRContext();
 
-  /// Return information about all registered IR dialects.
-  std::vector<Dialect *> getRegisteredDialects();
+  /// Return information about all IR dialects loaded in the context.
+  std::vector<Dialect *> getLoadedDialects();
+
+  /// Return the dialect registry associated with this context.
+  DialectRegistry &getDialectRegistry();
+
+  /// Return information about all available dialects in the registry in this
+  /// context.
+  std::vector<StringRef> getAvailableDialects();
 
   /// Get a registered IR dialect with the given namespace. If an exact match is
   /// not found, then return nullptr.
-  Dialect *getRegisteredDialect(StringRef name);
+  Dialect *getLoadedDialect(StringRef name);
 
   /// Get a registered IR dialect for the given derived dialect type. The
   /// derived type must provide a static 'getDialectNamespace' method.
-  template <typename T> T *getRegisteredDialect() {
-    return static_cast<T *>(getRegisteredDialect(T::getDialectNamespace()));
+  template <typename T> T *getLoadedDialect() {
+    return static_cast<T *>(getLoadedDialect(T::getDialectNamespace()));
   }
 
   /// Get (or create) a dialect for the given derived dialect type. The derived
   /// type must provide a static 'getDialectNamespace' method.
-  template <typename T>
-  T *getOrCreateDialect() {
-    return static_cast<T *>(getOrCreateDialect(
-        T::getDialectNamespace(), TypeID::get<T>(), [this]() {
+  template <typename T> T *getOrLoadDialect() {
+    return static_cast<T *>(
+        getOrLoadDialect(T::getDialectNamespace(), TypeID::get<T>(), [this]() {
           std::unique_ptr<T> dialect(new T(this));
-          dialect->dialectID = TypeID::get<T>();
           return dialect;
         }));
   }
 
+  /// Deprecated: load all globally registered dialects into this context.
+  /// This method will be removed soon, it can be used temporarily as we're
+  /// phasing out the global registry.
+  void loadAllGloballyRegisteredDialects();
+
+  /// Get (or create) a dialect for the given derived dialect name.
+  /// The dialect will be loaded from the registry if no dialect is found.
+  /// If no dialect is loaded for this name and none is available in the
+  /// registry, returns nullptr.
+  Dialect *getOrLoadDialect(StringRef name);
+
   /// Return true if we allow to create operation for unregistered dialects.
   bool allowsUnregisteredDialects();
 
@@ -123,10 +145,12 @@ class MLIRContext {
   const std::unique_ptr<MLIRContextImpl> impl;
 
   /// Get a dialect for the provided namespace and TypeID: abort the program if
-  /// a dialect exist for this namespace with 
diff erent TypeID. Returns a
-  /// pointer to the dialect owned by the context.
-  Dialect *getOrCreateDialect(StringRef dialectNamespace, TypeID dialectID,
-                              function_ref<std::unique_ptr<Dialect>()> ctor);
+  /// a dialect exist for this namespace with 
diff erent TypeID. If a dialect has
+  /// not been loaded for this namespace/TypeID yet, use the provided ctor to
+  /// create one on the fly and load it. Returns a pointer to the dialect owned
+  /// by the context.
+  Dialect *getOrLoadDialect(StringRef dialectNamespace, TypeID dialectID,
+                            function_ref<std::unique_ptr<Dialect>()> ctor);
 
   MLIRContext(const MLIRContext &) = delete;
   void operator=(const MLIRContext &) = delete;

diff  --git a/mlir/include/mlir/IR/OpBase.td b/mlir/include/mlir/IR/OpBase.td
index 9cc57a617289..a28410f028d5 100644
--- a/mlir/include/mlir/IR/OpBase.td
+++ b/mlir/include/mlir/IR/OpBase.td
@@ -244,6 +244,11 @@ class Dialect {
   // The description of the dialect.
   string description = ?;
 
+  // A list of dialects this dialect will load on construction as dependencies.
+  // These are dialects that this dialect may involved in canonicalization
+  // pattern or interfaces.
+  list<string> dependentDialects = [];
+
   // The C++ namespace that ops of this dialect should be placed into.
   //
   // By default, uses the name of the dialect as the only namespace. To avoid

diff  --git a/mlir/include/mlir/InitAllDialects.h b/mlir/include/mlir/InitAllDialects.h
index b76b26fe3483..a4566168138b 100644
--- a/mlir/include/mlir/InitAllDialects.h
+++ b/mlir/include/mlir/InitAllDialects.h
@@ -35,29 +35,32 @@
 
 namespace mlir {
 
+// Add all the MLIR dialects to the provided registry.
+inline void registerAllDialects(DialectRegistry &registry) {
+  registry.insert<acc::OpenACCDialect>();
+  registry.insert<AffineDialect>();
+  registry.insert<avx512::AVX512Dialect>();
+  registry.insert<gpu::GPUDialect>();
+  registry.insert<LLVM::LLVMAVX512Dialect>();
+  registry.insert<LLVM::LLVMDialect>();
+  registry.insert<linalg::LinalgDialect>();
+  registry.insert<scf::SCFDialect>();
+  registry.insert<omp::OpenMPDialect>();
+  registry.insert<quant::QuantizationDialect>();
+  registry.insert<spirv::SPIRVDialect>();
+  registry.insert<StandardOpsDialect>();
+  registry.insert<vector::VectorDialect>();
+  registry.insert<NVVM::NVVMDialect>();
+  registry.insert<ROCDL::ROCDLDialect>();
+  registry.insert<SDBMDialect>();
+  registry.insert<shape::ShapeDialect>();
+}
+
 // This function should be called before creating any MLIRContext if one expect
 // all the possible dialects to be made available to the context automatically.
 inline void registerAllDialects() {
-  static bool init_once = []() {
-    registerDialect<acc::OpenACCDialect>();
-    registerDialect<AffineDialect>();
-    registerDialect<avx512::AVX512Dialect>();
-    registerDialect<gpu::GPUDialect>();
-    registerDialect<LLVM::LLVMAVX512Dialect>();
-    registerDialect<LLVM::LLVMDialect>();
-    registerDialect<linalg::LinalgDialect>();
-    registerDialect<scf::SCFDialect>();
-    registerDialect<omp::OpenMPDialect>();
-    registerDialect<quant::QuantizationDialect>();
-    registerDialect<spirv::SPIRVDialect>();
-    registerDialect<StandardOpsDialect>();
-    registerDialect<vector::VectorDialect>();
-    registerDialect<NVVM::NVVMDialect>();
-    registerDialect<ROCDL::ROCDLDialect>();
-    registerDialect<SDBMDialect>();
-    registerDialect<shape::ShapeDialect>();
-    return true;
-  }();
+  static bool init_once =
+      ([]() { registerAllDialects(getGlobalDialectRegistry()); }(), true);
   (void)init_once;
 }
 } // namespace mlir

diff  --git a/mlir/include/mlir/Pass/Pass.h b/mlir/include/mlir/Pass/Pass.h
index 7c0f9bd958a1..ea361ae1162d 100644
--- a/mlir/include/mlir/Pass/Pass.h
+++ b/mlir/include/mlir/Pass/Pass.h
@@ -9,6 +9,7 @@
 #ifndef MLIR_PASS_PASS_H
 #define MLIR_PASS_PASS_H
 
+#include "mlir/IR/Dialect.h"
 #include "mlir/IR/Function.h"
 #include "mlir/Pass/AnalysisManager.h"
 #include "mlir/Pass/PassRegistry.h"
@@ -57,6 +58,13 @@ class Pass {
   /// Returns the derived pass name.
   virtual StringRef getName() const = 0;
 
+  /// Register dependent dialects for the current pass.
+  /// A pass is expected to register the dialects it will create operations for,
+  /// other than dialect that exists in the input. For example, a pass that
+  /// converts from Linalg to Affine would register the Affine dialect but does
+  /// not need to register Linalg.
+  virtual void getDependentDialects(DialectRegistry &registry) const {}
+
   /// Returns the command line argument used when registering this pass. Return
   /// an empty string if one does not exist.
   virtual StringRef getArgument() const {

diff  --git a/mlir/include/mlir/Pass/PassBase.td b/mlir/include/mlir/Pass/PassBase.td
index 54b44031559e..749d042d46d3 100644
--- a/mlir/include/mlir/Pass/PassBase.td
+++ b/mlir/include/mlir/Pass/PassBase.td
@@ -78,6 +78,9 @@ class PassBase<string passArg, string base> {
   // A C++ constructor call to create an instance of this pass.
   code constructor = [{}];
 
+  // A list of dialects this pass may produce operations in.
+  list<string> dependentDialects = [];
+
   // A set of options provided by this pass.
   list<Option> options = [];
 

diff  --git a/mlir/include/mlir/Pass/PassManager.h b/mlir/include/mlir/Pass/PassManager.h
index 9cbfb0b27710..29e7c07c2ee4 100644
--- a/mlir/include/mlir/Pass/PassManager.h
+++ b/mlir/include/mlir/Pass/PassManager.h
@@ -9,6 +9,7 @@
 #ifndef MLIR_PASS_PASSMANAGER_H
 #define MLIR_PASS_PASSMANAGER_H
 
+#include "mlir/IR/Dialect.h"
 #include "mlir/IR/OperationSupport.h"
 #include "mlir/Support/LogicalResult.h"
 #include "llvm/ADT/Optional.h"
@@ -58,6 +59,14 @@ class OpPassManager {
   pass_iterator end();
   iterator_range<pass_iterator> getPasses() { return {begin(), end()}; }
 
+  using const_pass_iterator = llvm::pointee_iterator<
+      std::vector<std::unique_ptr<Pass>>::const_iterator>;
+  const_pass_iterator begin() const;
+  const_pass_iterator end() const;
+  iterator_range<const_pass_iterator> getPasses() const {
+    return {begin(), end()};
+  }
+
   /// Run the held passes over the given operation.
   LogicalResult run(Operation *op, AnalysisManager am);
 
@@ -100,6 +109,11 @@ class OpPassManager {
   /// Merge the pass statistics of this class into 'other'.
   void mergeStatisticsInto(OpPassManager &other);
 
+  /// Register dependent dialects for the current pass manager.
+  /// This is forwarding to every pass in this PassManager, see the
+  /// documentation for the same method on the Pass class.
+  void getDependentDialects(DialectRegistry &dialects) const;
+
 private:
   OpPassManager(OperationName name, bool verifyPasses);
 

diff  --git a/mlir/include/mlir/Support/MlirOptMain.h b/mlir/include/mlir/Support/MlirOptMain.h
index f235ea3fa520..741276b38f1e 100644
--- a/mlir/include/mlir/Support/MlirOptMain.h
+++ b/mlir/include/mlir/Support/MlirOptMain.h
@@ -22,10 +22,15 @@ namespace mlir {
 struct LogicalResult;
 class PassPipelineCLParser;
 
+/// Run an passPipeline on the provided memory buffer loaded as an MLIRModule.
+/// The preloadDialectsInContext option will trigger an option upfront loading
+/// of all dialects from the global registry in the MLIRContext. This option is
+/// deprecated and will be removed soon.
 LogicalResult MlirOptMain(llvm::raw_ostream &os,
                           std::unique_ptr<llvm::MemoryBuffer> buffer,
                           const PassPipelineCLParser &passPipeline,
                           bool splitInputFile, bool verifyDiagnostics,
-                          bool verifyPasses, bool allowUnregisteredDialects);
+                          bool verifyPasses, bool allowUnregisteredDialects,
+                          bool preloadDialectsInContext = false);
 
 } // end namespace mlir

diff  --git a/mlir/include/mlir/TableGen/Dialect.h b/mlir/include/mlir/TableGen/Dialect.h
index 5e85806f377f..99217d8c7d3d 100644
--- a/mlir/include/mlir/TableGen/Dialect.h
+++ b/mlir/include/mlir/TableGen/Dialect.h
@@ -14,6 +14,7 @@
 
 #include "mlir/Support/LLVM.h"
 #include <string>
+#include <vector>
 
 namespace llvm {
 class Record;
@@ -25,7 +26,7 @@ namespace tblgen {
 // and provides helper methods for accessing them.
 class Dialect {
 public:
-  explicit Dialect(const llvm::Record *def) : def(def) {}
+  explicit Dialect(const llvm::Record *def);
 
   // Returns the name of this dialect.
   StringRef getName() const;
@@ -43,6 +44,10 @@ class Dialect {
   // Returns the description of the dialect. Returns empty string if none.
   StringRef getDescription() const;
 
+  // Returns the list of dialect (class names) that this dialect depends on.
+  // These are dialects that will be loaded on construction of this dialect.
+  ArrayRef<StringRef> getDependentDialects() const;
+
   // Returns the dialects extra class declaration code.
   llvm::Optional<StringRef> getExtraClassDeclaration() const;
 
@@ -70,6 +75,7 @@ class Dialect {
 
 private:
   const llvm::Record *def;
+  std::vector<StringRef> dependentDialects;
 };
 } // end namespace tblgen
 } // end namespace mlir

diff  --git a/mlir/include/mlir/TableGen/Pass.h b/mlir/include/mlir/TableGen/Pass.h
index 02427e42a525..968c85416965 100644
--- a/mlir/include/mlir/TableGen/Pass.h
+++ b/mlir/include/mlir/TableGen/Pass.h
@@ -94,6 +94,9 @@ class Pass {
   /// Return the C++ constructor call to create an instance of this pass.
   StringRef getConstructor() const;
 
+  /// Return the dialects this pass needs to be registered.
+  ArrayRef<StringRef> getDependentDialects() const;
+
   /// Return the options provided by this pass.
   ArrayRef<PassOption> getOptions() const;
 
@@ -104,6 +107,7 @@ class Pass {
 
 private:
   const llvm::Record *def;
+  std::vector<StringRef> dependentDialects;
   std::vector<PassOption> options;
   std::vector<PassStatistic> statistics;
 };

diff  --git a/mlir/include/mlir/Transforms/Passes.td b/mlir/include/mlir/Transforms/Passes.td
index 778780573498..3292d5e7dec2 100644
--- a/mlir/include/mlir/Transforms/Passes.td
+++ b/mlir/include/mlir/Transforms/Passes.td
@@ -162,6 +162,8 @@ def BufferPlacement : FunctionPass<"buffer-placement"> {
 
   }];
   let constructor = "mlir::createBufferPlacementPass()";
+  // TODO: this pass likely shouldn't depend on Linalg?
+  let dependentDialects = ["linalg::LinalgDialect"];
 }
 
 def Canonicalizer : Pass<"canonicalize"> {

diff  --git a/mlir/lib/CAPI/IR/IR.cpp b/mlir/lib/CAPI/IR/IR.cpp
index 4ccfb45f2c43..2417c1d6d7e4 100644
--- a/mlir/lib/CAPI/IR/IR.cpp
+++ b/mlir/lib/CAPI/IR/IR.cpp
@@ -9,9 +9,11 @@
 #include "mlir-c/IR.h"
 
 #include "mlir/IR/Attributes.h"
+#include "mlir/IR/Dialect.h"
 #include "mlir/IR/Module.h"
 #include "mlir/IR/Operation.h"
 #include "mlir/IR/Types.h"
+#include "mlir/InitAllDialects.h"
 #include "mlir/Parser.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -89,12 +91,17 @@ class CallbackOstream : public llvm::raw_ostream {
 /* ========================================================================== */
 
 MlirContext mlirContextCreate() {
-  auto *context = new MLIRContext;
+  auto *context = new MLIRContext(false);
   return wrap(context);
 }
 
 void mlirContextDestroy(MlirContext context) { delete unwrap(context); }
 
+void mlirContextLoadAllDialects(MlirContext context) {
+  registerAllDialects(unwrap(context));
+  getGlobalDialectRegistry().loadAll(unwrap(context));
+}
+
 /* ========================================================================== */
 /* Location API.                                                              */
 /* ========================================================================== */

diff  --git a/mlir/lib/Conversion/GPUToVulkan/ConvertGPULaunchFuncToVulkanLaunchFunc.cpp b/mlir/lib/Conversion/GPUToVulkan/ConvertGPULaunchFuncToVulkanLaunchFunc.cpp
index 1ebf48174aaf..42673936b878 100644
--- a/mlir/lib/Conversion/GPUToVulkan/ConvertGPULaunchFuncToVulkanLaunchFunc.cpp
+++ b/mlir/lib/Conversion/GPUToVulkan/ConvertGPULaunchFuncToVulkanLaunchFunc.cpp
@@ -16,6 +16,7 @@
 #include "../PassDetail.h"
 #include "mlir/Conversion/GPUToVulkan/ConvertGPUToVulkanPass.h"
 #include "mlir/Dialect/GPU/GPUDialect.h"
+#include "mlir/Dialect/SPIRV/SPIRVDialect.h"
 #include "mlir/Dialect/SPIRV/SPIRVOps.h"
 #include "mlir/Dialect/SPIRV/Serialization.h"
 #include "mlir/Dialect/StandardOps/IR/Ops.h"

diff  --git a/mlir/lib/Conversion/LinalgToLLVM/LinalgToLLVM.cpp b/mlir/lib/Conversion/LinalgToLLVM/LinalgToLLVM.cpp
index 7b57854dde98..0460d98b44a4 100644
--- a/mlir/lib/Conversion/LinalgToLLVM/LinalgToLLVM.cpp
+++ b/mlir/lib/Conversion/LinalgToLLVM/LinalgToLLVM.cpp
@@ -19,6 +19,7 @@
 #include "mlir/Dialect/Linalg/IR/LinalgOps.h"
 #include "mlir/Dialect/Linalg/IR/LinalgTypes.h"
 #include "mlir/Dialect/Linalg/Passes.h"
+#include "mlir/Dialect/SCF/SCF.h"
 #include "mlir/Dialect/StandardOps/EDSC/Intrinsics.h"
 #include "mlir/IR/AffineExpr.h"
 #include "mlir/IR/AffineMap.h"

diff  --git a/mlir/lib/Conversion/PassDetail.h b/mlir/lib/Conversion/PassDetail.h
index 6da0bc81e7af..7fa5a5a92f20 100644
--- a/mlir/lib/Conversion/PassDetail.h
+++ b/mlir/lib/Conversion/PassDetail.h
@@ -12,11 +12,43 @@
 #include "mlir/Pass/Pass.h"
 
 namespace mlir {
+class AffineDialect;
+class StandardOpsDialect;
+
+// Forward declaration from Dialect.h
+template <typename ConcreteDialect>
+void registerDialect(DialectRegistry &registry);
 
 namespace gpu {
+class GPUDialect;
 class GPUModuleOp;
 } // end namespace gpu
 
+namespace LLVM {
+class LLVMDialect;
+class LLVMAVX512Dialect;
+} // end namespace LLVM
+
+namespace NVVM {
+class NVVMDialect;
+} // end namespace NVVM
+
+namespace ROCDL {
+class ROCDLDialect;
+} // end namespace ROCDL
+
+namespace scf {
+class SCFDialect;
+} // end namespace scf
+
+namespace spirv {
+class SPIRVDialect;
+} // end namespace spirv
+
+namespace vector {
+class VectorDialect;
+} // end namespace vector
+
 #define GEN_PASS_CLASSES
 #include "mlir/Conversion/Passes.h.inc"
 

diff  --git a/mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp b/mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp
index efe4a3c958d7..60967039b545 100644
--- a/mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp
+++ b/mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp
@@ -125,7 +125,7 @@ LLVMTypeConverter::LLVMTypeConverter(MLIRContext *ctx)
 /// Create an LLVMTypeConverter using custom LowerToLLVMOptions.
 LLVMTypeConverter::LLVMTypeConverter(MLIRContext *ctx,
                                      const LowerToLLVMOptions &options)
-    : llvmDialect(ctx->getRegisteredDialect<LLVM::LLVMDialect>()),
+    : llvmDialect(ctx->getOrLoadDialect<LLVM::LLVMDialect>()),
       options(options) {
   assert(llvmDialect && "LLVM IR dialect is not registered");
   if (options.indexBitwidth == kDeriveIndexBitwidthFromDataLayout)

diff  --git a/mlir/lib/Conversion/StandardToSPIRV/LegalizeStandardForSPIRV.cpp b/mlir/lib/Conversion/StandardToSPIRV/LegalizeStandardForSPIRV.cpp
index 19643d271f8d..a2e608dcb713 100644
--- a/mlir/lib/Conversion/StandardToSPIRV/LegalizeStandardForSPIRV.cpp
+++ b/mlir/lib/Conversion/StandardToSPIRV/LegalizeStandardForSPIRV.cpp
@@ -14,6 +14,7 @@
 #include "../PassDetail.h"
 #include "mlir/Conversion/StandardToSPIRV/ConvertStandardToSPIRV.h"
 #include "mlir/Conversion/StandardToSPIRV/ConvertStandardToSPIRVPass.h"
+#include "mlir/Dialect/SPIRV/SPIRVDialect.h"
 #include "mlir/Dialect/StandardOps/IR/Ops.h"
 #include "mlir/Dialect/Vector/VectorOps.h"
 #include "mlir/IR/PatternMatch.h"

diff  --git a/mlir/lib/Dialect/Affine/Transforms/PassDetail.h b/mlir/lib/Dialect/Affine/Transforms/PassDetail.h
index 3bae0592b3d4..da8f7ac3fc81 100644
--- a/mlir/lib/Dialect/Affine/Transforms/PassDetail.h
+++ b/mlir/lib/Dialect/Affine/Transforms/PassDetail.h
@@ -12,6 +12,16 @@
 #include "mlir/Pass/Pass.h"
 
 namespace mlir {
+// Forward declaration from Dialect.h
+template <typename ConcreteDialect>
+void registerDialect(DialectRegistry &registry);
+
+namespace linalg {
+class LinalgDialect;
+} // end namespace linalg
+namespace vector {
+class VectorDialect;
+} // end namespace vector
 
 #define GEN_PASS_CLASSES
 #include "mlir/Dialect/Affine/Passes.h.inc"

diff  --git a/mlir/lib/Dialect/Linalg/IR/LinalgOps.cpp b/mlir/lib/Dialect/Linalg/IR/LinalgOps.cpp
index 009699be5263..bf18c6cddd7e 100644
--- a/mlir/lib/Dialect/Linalg/IR/LinalgOps.cpp
+++ b/mlir/lib/Dialect/Linalg/IR/LinalgOps.cpp
@@ -1224,6 +1224,7 @@ template <typename NamedStructuredOpType>
 static ParseResult parseNamedStructuredOp(OpAsmParser &parser,
                                           OperationState &result) {
   SmallVector<OpAsmParser::OperandType, 8> operandsInfo;
+  result.getContext()->getOrLoadDialect<StandardOpsDialect>();
 
   // Optional attributes may be added.
   if (parser.parseOperandList(operandsInfo) ||

diff  --git a/mlir/lib/Dialect/Linalg/Transforms/PassDetail.h b/mlir/lib/Dialect/Linalg/Transforms/PassDetail.h
index 7fa05ff12120..0415aeb8a1fd 100644
--- a/mlir/lib/Dialect/Linalg/Transforms/PassDetail.h
+++ b/mlir/lib/Dialect/Linalg/Transforms/PassDetail.h
@@ -9,9 +9,18 @@
 #ifndef DIALECT_LINALG_TRANSFORMS_PASSDETAIL_H_
 #define DIALECT_LINALG_TRANSFORMS_PASSDETAIL_H_
 
+#include "mlir/Dialect/Affine/IR/AffineOps.h"
+#include "mlir/IR/Dialect.h"
 #include "mlir/Pass/Pass.h"
 
 namespace mlir {
+// Forward declaration from Dialect.h
+template <typename ConcreteDialect>
+void registerDialect(DialectRegistry &registry);
+
+namespace scf {
+class SCFDialect;
+} // end namespace scf
 
 #define GEN_PASS_CLASSES
 #include "mlir/Dialect/Linalg/Passes.h.inc"

diff  --git a/mlir/lib/Dialect/SCF/Transforms/PassDetail.h b/mlir/lib/Dialect/SCF/Transforms/PassDetail.h
index 95f8636b27c1..6fa7f227d3da 100644
--- a/mlir/lib/Dialect/SCF/Transforms/PassDetail.h
+++ b/mlir/lib/Dialect/SCF/Transforms/PassDetail.h
@@ -12,6 +12,11 @@
 #include "mlir/Pass/Pass.h"
 
 namespace mlir {
+// Forward declaration from Dialect.h
+template <typename ConcreteDialect>
+void registerDialect(DialectRegistry &registry);
+
+class AffineDialect;
 
 #define GEN_PASS_CLASSES
 #include "mlir/Dialect/SCF/Passes.h.inc"

diff  --git a/mlir/lib/Dialect/SDBM/SDBMExpr.cpp b/mlir/lib/Dialect/SDBM/SDBMExpr.cpp
index 435c7fe25f0c..a1971c3da3b2 100644
--- a/mlir/lib/Dialect/SDBM/SDBMExpr.cpp
+++ b/mlir/lib/Dialect/SDBM/SDBMExpr.cpp
@@ -517,7 +517,7 @@ Optional<SDBMExpr> SDBMExpr::tryConvertAffineExpr(AffineExpr affine) {
 
     SDBMDialect *dialect;
   } converter;
-  converter.dialect = affine.getContext()->getRegisteredDialect<SDBMDialect>();
+  converter.dialect = affine.getContext()->getOrLoadDialect<SDBMDialect>();
 
   if (auto result = converter.visit(affine))
     return result;

diff  --git a/mlir/lib/ExecutionEngine/JitRunner.cpp b/mlir/lib/ExecutionEngine/JitRunner.cpp
index 7959183e8968..2b18adb37347 100644
--- a/mlir/lib/ExecutionEngine/JitRunner.cpp
+++ b/mlir/lib/ExecutionEngine/JitRunner.cpp
@@ -259,7 +259,9 @@ int mlir::JitRunnerMain(
     }
   }
 
-  MLIRContext context;
+  MLIRContext context(/*loadAllDialects=*/false);
+  registerAllDialects(&context);
+
   auto m = parseMLIRInput(options.inputFilename, &context);
   if (!m) {
     llvm::errs() << "could not parse the input IR\n";

diff  --git a/mlir/lib/IR/Dialect.cpp b/mlir/lib/IR/Dialect.cpp
index 555bb2bf0eb4..f2f0a63ce883 100644
--- a/mlir/lib/IR/Dialect.cpp
+++ b/mlir/lib/IR/Dialect.cpp
@@ -27,21 +27,25 @@ DialectAsmParser::~DialectAsmParser() {}
 //===----------------------------------------------------------------------===//
 
 /// Registry for all dialect allocation functions.
-static llvm::ManagedStatic<llvm::MapVector<TypeID, DialectAllocatorFunction>>
-    dialectRegistry;
-
-void Dialect::registerDialectAllocator(
-    TypeID typeID, const DialectAllocatorFunction &function) {
-  assert(function &&
-         "Attempting to register an empty dialect initialize function");
-  dialectRegistry->insert({typeID, function});
+static llvm::ManagedStatic<DialectRegistry> dialectRegistry;
+DialectRegistry &mlir::getGlobalDialectRegistry() { return *dialectRegistry; }
+
+Dialect *DialectRegistry::loadByName(StringRef name, MLIRContext *context) {
+  auto it = registry.find(std::string(name));
+  if (it == registry.end())
+    return nullptr;
+  return it->second.second(context);
 }
 
-/// Registers all dialects and hooks from the global registries with the
-/// specified MLIRContext.
-void mlir::registerAllDialects(MLIRContext *context) {
-  for (const auto &it : *dialectRegistry)
-    it.second(context);
+void DialectRegistry::insert(TypeID typeID, StringRef name,
+                             DialectAllocatorFunction ctor) {
+  auto inserted =
+      registry.insert(std::make_pair(name, std::make_pair(typeID, ctor)));
+  if (!inserted.second && inserted.first->second.first != typeID) {
+    llvm::report_fatal_error(
+        "Trying to register 
diff erent dialects for the same namespace: " +
+        name);
+  }
 }
 
 //===----------------------------------------------------------------------===//
@@ -119,7 +123,7 @@ DialectInterface::~DialectInterface() {}
 
 DialectInterfaceCollectionBase::DialectInterfaceCollectionBase(
     MLIRContext *ctx, TypeID interfaceKind) {
-  for (auto *dialect : ctx->getRegisteredDialects()) {
+  for (auto *dialect : ctx->getLoadedDialects()) {
     if (auto *interface = dialect->getRegisteredInterface(interfaceKind)) {
       interfaces.insert(interface);
       orderedInterfaces.push_back(interface);

diff  --git a/mlir/lib/IR/MLIRContext.cpp b/mlir/lib/IR/MLIRContext.cpp
index 0d66070657aa..ed8e3db919b3 100644
--- a/mlir/lib/IR/MLIRContext.cpp
+++ b/mlir/lib/IR/MLIRContext.cpp
@@ -31,10 +31,13 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/RWMutex.h"
 #include "llvm/Support/raw_ostream.h"
 #include <memory>
 
+#define DEBUG_TYPE "mlircontext"
+
 using namespace mlir;
 using namespace mlir::detail;
 
@@ -275,7 +278,8 @@ class MLIRContextImpl {
 
   /// This is a list of dialects that are created referring to this context.
   /// The MLIRContext owns the objects.
-  std::vector<std::unique_ptr<Dialect>> dialects;
+  DenseMap<StringRef, std::unique_ptr<Dialect>> loadedDialects;
+  DialectRegistry dialectsRegistry;
 
   /// This is a mapping from operation name to AbstractOperation for registered
   /// operations.
@@ -346,7 +350,7 @@ class MLIRContextImpl {
 };
 } // end namespace mlir
 
-MLIRContext::MLIRContext() : impl(new MLIRContextImpl()) {
+MLIRContext::MLIRContext(bool loadAllDialects) : impl(new MLIRContextImpl()) {
   // Initialize values based on the command line flags if they were provided.
   if (clOptions.isConstructed()) {
     disableMultithreading(clOptions->disableThreading);
@@ -355,8 +359,9 @@ MLIRContext::MLIRContext() : impl(new MLIRContextImpl()) {
   }
 
   // Register dialects with this context.
-  getOrCreateDialect<BuiltinDialect>();
-  registerAllDialects(this);
+  getOrLoadDialect<BuiltinDialect>();
+  if (loadAllDialects)
+    loadAllGloballyRegisteredDialects();
 
   // Initialize several common attributes and types to avoid the need to lock
   // the context when accessing them.
@@ -438,54 +443,72 @@ DiagnosticEngine &MLIRContext::getDiagEngine() { return getImpl().diagEngine; }
 // Dialect and Operation Registration
 //===----------------------------------------------------------------------===//
 
+DialectRegistry &MLIRContext::getDialectRegistry() {
+  return impl->dialectsRegistry;
+}
+
 /// Return information about all registered IR dialects.
-std::vector<Dialect *> MLIRContext::getRegisteredDialects() {
+std::vector<Dialect *> MLIRContext::getLoadedDialects() {
   std::vector<Dialect *> result;
-  result.reserve(impl->dialects.size());
-  for (auto &dialect : impl->dialects)
-    result.push_back(dialect.get());
+  result.reserve(impl->loadedDialects.size());
+  for (auto &dialect : impl->loadedDialects) {
+    result.push_back(dialect.second.get());
+  }
+  llvm::sort(result, [](Dialect *lhs, Dialect *rhs) {
+    return lhs->getNamespace() < rhs->getNamespace();
+  });
+  return result;
+}
+std::vector<StringRef> MLIRContext::getAvailableDialects() {
+  std::vector<StringRef> result;
+  for (auto &dialect : impl->dialectsRegistry)
+    result.push_back(dialect.first);
   return result;
 }
 
 /// Get a registered IR dialect with the given namespace. If none is found,
 /// then return nullptr.
-Dialect *MLIRContext::getRegisteredDialect(StringRef name) {
+Dialect *MLIRContext::getLoadedDialect(StringRef name) {
   // Dialects are sorted by name, so we can use binary search for lookup.
-  auto it = llvm::lower_bound(
-      impl->dialects, name,
-      [](const auto &lhs, StringRef rhs) { return lhs->getNamespace() < rhs; });
-  return (it != impl->dialects.end() && (*it)->getNamespace() == name)
-             ? (*it).get()
-             : nullptr;
+  auto it = impl->loadedDialects.find(name);
+  return (it != impl->loadedDialects.end()) ? it->second.get() : nullptr;
+}
+
+Dialect *MLIRContext::getOrLoadDialect(StringRef name) {
+  Dialect *dialect = getLoadedDialect(name);
+  if (dialect)
+    return dialect;
+  return impl->dialectsRegistry.loadByName(name, this);
 }
 
 /// Get a dialect for the provided namespace and TypeID: abort the program if a
 /// dialect exist for this namespace with 
diff erent TypeID. Returns a pointer to
 /// the dialect owned by the context.
 Dialect *
-MLIRContext::getOrCreateDialect(StringRef dialectNamespace, TypeID dialectID,
-                                function_ref<std::unique_ptr<Dialect>()> ctor) {
+MLIRContext::getOrLoadDialect(StringRef dialectNamespace, TypeID dialectID,
+                              function_ref<std::unique_ptr<Dialect>()> ctor) {
   auto &impl = getImpl();
   // Get the correct insertion position sorted by namespace.
-  auto insertPt =
-      llvm::lower_bound(impl.dialects, nullptr,
-                        [&](const std::unique_ptr<Dialect> &lhs,
-                            const std::unique_ptr<Dialect> &rhs) {
-                          if (!lhs)
-                            return dialectNamespace < rhs->getNamespace();
-                          return lhs->getNamespace() < dialectNamespace;
-                        });
+  std::unique_ptr<Dialect> &dialect = impl.loadedDialects[dialectNamespace];
+
+  if (!dialect) {
+    LLVM_DEBUG(llvm::dbgs()
+               << "Load new dialect in Context" << dialectNamespace);
+    dialect = ctor();
+    assert(dialect && "dialect ctor failed");
+    return dialect.get();
+  }
 
   // Abort if dialect with namespace has already been registered.
-  if (insertPt != impl.dialects.end() &&
-      (*insertPt)->getNamespace() == dialectNamespace) {
-    if ((*insertPt)->getTypeID() == dialectID)
-      return insertPt->get();
+  if (dialect->getTypeID() != dialectID)
     llvm::report_fatal_error("a dialect with namespace '" + dialectNamespace +
                              "' has already been registered");
-  }
-  auto it = impl.dialects.insert(insertPt, ctor());
-  return &**it;
+
+  return dialect.get();
+}
+
+void MLIRContext::loadAllGloballyRegisteredDialects() {
+  getGlobalDialectRegistry().loadAll(this);
 }
 
 bool MLIRContext::allowsUnregisteredDialects() {

diff  --git a/mlir/lib/IR/Operation.cpp b/mlir/lib/IR/Operation.cpp
index 152ed0124767..dce570a9f368 100644
--- a/mlir/lib/IR/Operation.cpp
+++ b/mlir/lib/IR/Operation.cpp
@@ -214,7 +214,7 @@ Dialect *Operation::getDialect() {
 
   // If this operation hasn't been registered or doesn't have abstract
   // operation, try looking up the dialect name in the context.
-  return getContext()->getRegisteredDialect(getName().getDialect());
+  return getContext()->getLoadedDialect(getName().getDialect());
 }
 
 Region *Operation::getParentRegion() {

diff  --git a/mlir/lib/IR/Verifier.cpp b/mlir/lib/IR/Verifier.cpp
index b1aed8842dc4..4caf9891383c 100644
--- a/mlir/lib/IR/Verifier.cpp
+++ b/mlir/lib/IR/Verifier.cpp
@@ -50,7 +50,7 @@ class OperationVerifier {
   Dialect *getDialectForAttribute(const NamedAttribute &attr) {
     assert(attr.first.strref().contains('.') && "expected dialect attribute");
     auto dialectNamePair = attr.first.strref().split('.');
-    return ctx->getRegisteredDialect(dialectNamePair.first);
+    return ctx->getLoadedDialect(dialectNamePair.first);
   }
 
 private:
@@ -218,7 +218,7 @@ LogicalResult OperationVerifier::verifyOperation(Operation &op) {
   auto it = dialectAllowsUnknownOps.find(dialectPrefix);
   if (it == dialectAllowsUnknownOps.end()) {
     // If the operation dialect is registered, query it directly.
-    if (auto *dialect = ctx->getRegisteredDialect(dialectPrefix))
+    if (auto *dialect = ctx->getLoadedDialect(dialectPrefix))
       it = dialectAllowsUnknownOps
                .try_emplace(dialectPrefix, dialect->allowsUnknownOperations())
                .first;

diff  --git a/mlir/lib/Parser/AttributeParser.cpp b/mlir/lib/Parser/AttributeParser.cpp
index 1c1261e6d765..37ee938a4bcd 100644
--- a/mlir/lib/Parser/AttributeParser.cpp
+++ b/mlir/lib/Parser/AttributeParser.cpp
@@ -12,6 +12,7 @@
 
 #include "Parser.h"
 #include "mlir/IR/AffineMap.h"
+#include "mlir/IR/Dialect.h"
 #include "mlir/IR/IntegerSet.h"
 #include "mlir/IR/StandardTypes.h"
 #include "llvm/ADT/StringExtras.h"
@@ -246,6 +247,11 @@ ParseResult Parser::parseAttributeDict(NamedAttrList &attributes) {
       return emitError("duplicate key in dictionary attribute");
     consumeToken();
 
+    // Lazy load a dialect in the context if there is a possible namespace.
+    auto splitName = nameId->strref().split('.');
+    if (!splitName.second.empty())
+      getContext()->getOrLoadDialect(splitName.first);
+
     // Try to parse the '=' for the attribute value.
     if (!consumeIf(Token::equal)) {
       // If there is no '=', we treat this as a unit attribute.
@@ -817,7 +823,9 @@ Attribute Parser::parseOpaqueElementsAttr(Type attrType) {
     return (emitError("expected dialect namespace"), nullptr);
 
   auto name = getToken().getStringValue();
-  auto *dialect = builder.getContext()->getRegisteredDialect(name);
+  // Lazy load a dialect in the context if there is a possible namespace.
+  Dialect *dialect = builder.getContext()->getOrLoadDialect(name);
+
   // TODO: Allow for having an unknown dialect on an opaque
   // attribute. Otherwise, it can't be roundtripped without having the dialect
   // registered.

diff  --git a/mlir/lib/Parser/DialectSymbolParser.cpp b/mlir/lib/Parser/DialectSymbolParser.cpp
index 3b522a876f25..d45ddf071989 100644
--- a/mlir/lib/Parser/DialectSymbolParser.cpp
+++ b/mlir/lib/Parser/DialectSymbolParser.cpp
@@ -526,7 +526,8 @@ Attribute Parser::parseExtendedAttr(Type type) {
           return Attribute();
 
         // If we found a registered dialect, then ask it to parse the attribute.
-        if (auto *dialect = state.context->getRegisteredDialect(dialectName)) {
+        if (Dialect *dialect =
+                builder.getContext()->getOrLoadDialect(dialectName)) {
           return parseSymbol<Attribute>(
               symbolData, state.context, state.symbols, [&](Parser &parser) {
                 CustomDialectAsmParser customParser(symbolData, parser);
@@ -563,7 +564,9 @@ Type Parser::parseExtendedType() {
       [&](StringRef dialectName, StringRef symbolData,
           llvm::SMLoc loc) -> Type {
         // If we found a registered dialect, then ask it to parse the type.
-        if (auto *dialect = state.context->getRegisteredDialect(dialectName)) {
+        auto *dialect = state.context->getOrLoadDialect(dialectName);
+
+        if (dialect) {
           return parseSymbol<Type>(
               symbolData, state.context, state.symbols, [&](Parser &parser) {
                 CustomDialectAsmParser customParser(symbolData, parser);

diff  --git a/mlir/lib/Parser/Parser.cpp b/mlir/lib/Parser/Parser.cpp
index 3a995a4e2b04..837b08ca54c0 100644
--- a/mlir/lib/Parser/Parser.cpp
+++ b/mlir/lib/Parser/Parser.cpp
@@ -12,6 +12,7 @@
 
 #include "Parser.h"
 #include "mlir/IR/AffineMap.h"
+#include "mlir/IR/Dialect.h"
 #include "mlir/IR/Module.h"
 #include "mlir/IR/Verifier.h"
 #include "mlir/Parser.h"
@@ -727,7 +728,7 @@ Operation *OperationParser::parseGenericOperation() {
   // Get location information for the operation.
   auto srcLocation = getEncodedSourceLocation(getToken().getLoc());
 
-  auto name = getToken().getStringValue();
+  std::string name = getToken().getStringValue();
   if (name.empty())
     return (emitError("empty operation name is invalid"), nullptr);
   if (name.find('\0') != StringRef::npos)
@@ -737,6 +738,15 @@ Operation *OperationParser::parseGenericOperation() {
 
   OperationState result(srcLocation, name);
 
+  // Lazy load dialects in the context as needed.
+  if (!result.name.getAbstractOperation()) {
+    StringRef dialectName = StringRef(name).split('.').first;
+    if (!getContext()->getLoadedDialect(dialectName) &&
+        getContext()->getOrLoadDialect(dialectName)) {
+      result.name = OperationName(name, getContext());
+    }
+  }
+
   // Parse the operand list.
   SmallVector<SSAUseInfo, 8> operandInfos;
   if (parseToken(Token::l_paren, "expected '(' to start operand list") ||
@@ -1442,17 +1452,28 @@ class CustomOpAsmParser : public OpAsmParser {
 
 Operation *
 OperationParser::parseCustomOperation(ArrayRef<ResultRecord> resultIDs) {
-  auto opLoc = getToken().getLoc();
-  auto opName = getTokenSpelling();
+  llvm::SMLoc opLoc = getToken().getLoc();
+  StringRef opName = getTokenSpelling();
 
   auto *opDefinition = AbstractOperation::lookup(opName, getContext());
-  if (!opDefinition && !opName.contains('.')) {
-    // If the operation name has no namespace prefix we treat it as a standard
-    // operation and prefix it with "std".
-    // TODO: Would it be better to just build a mapping of the registered
-    // operations in the standard dialect?
-    opDefinition =
-        AbstractOperation::lookup(Twine("std." + opName).str(), getContext());
+  if (!opDefinition) {
+    if (opName.contains('.')) {
+      // This op has a dialect, we try to check if we can register it in the
+      // context on the fly.
+      StringRef dialectName = opName.split('.').first;
+      if (!getContext()->getLoadedDialect(dialectName) &&
+          getContext()->getOrLoadDialect(dialectName)) {
+        opDefinition = AbstractOperation::lookup(opName, getContext());
+      }
+    } else {
+      // If the operation name has no namespace prefix we treat it as a standard
+      // operation and prefix it with "std".
+      // TODO: Would it be better to just build a mapping of the registered
+      // operations in the standard dialect?
+      if (getContext()->getOrLoadDialect("std"))
+        opDefinition = AbstractOperation::lookup(Twine("std." + opName).str(),
+                                                 getContext());
+    }
   }
 
   if (!opDefinition) {

diff  --git a/mlir/lib/Pass/Pass.cpp b/mlir/lib/Pass/Pass.cpp
index b791bf483e67..9debd115e681 100644
--- a/mlir/lib/Pass/Pass.cpp
+++ b/mlir/lib/Pass/Pass.cpp
@@ -290,6 +290,13 @@ OpPassManager::pass_iterator OpPassManager::begin() {
 }
 OpPassManager::pass_iterator OpPassManager::end() { return impl->passes.end(); }
 
+OpPassManager::const_pass_iterator OpPassManager::begin() const {
+  return impl->passes.begin();
+}
+OpPassManager::const_pass_iterator OpPassManager::end() const {
+  return impl->passes.end();
+}
+
 /// Run all of the passes in this manager over the current operation.
 LogicalResult OpPassManager::run(Operation *op, AnalysisManager am) {
   // Run each of the held passes.
@@ -346,6 +353,16 @@ void OpPassManager::printAsTextualPipeline(raw_ostream &os) {
   ::printAsTextualPipeline(impl->passes, os);
 }
 
+static void registerDialectsForPipeline(const OpPassManager &pm,
+                                        DialectRegistry &dialects) {
+  for (const Pass &pass : pm.getPasses())
+    pass.getDependentDialects(dialects);
+}
+
+void OpPassManager::getDependentDialects(DialectRegistry &dialects) const {
+  registerDialectsForPipeline(*this, dialects);
+}
+
 //===----------------------------------------------------------------------===//
 // OpToOpPassAdaptor
 //===----------------------------------------------------------------------===//
@@ -378,6 +395,11 @@ OpToOpPassAdaptor::OpToOpPassAdaptor(OpPassManager &&mgr) {
   mgrs.emplace_back(std::move(mgr));
 }
 
+void OpToOpPassAdaptor::getDependentDialects(DialectRegistry &dialects) const {
+  for (auto &pm : mgrs)
+    pm.getDependentDialects(dialects);
+}
+
 /// Merge the current pass adaptor into given 'rhs'.
 void OpToOpPassAdaptor::mergeInto(OpToOpPassAdaptor &rhs) {
   for (auto &pm : mgrs) {
@@ -721,6 +743,11 @@ LogicalResult PassManager::run(ModuleOp module) {
   // pipeline.
   getImpl().coalesceAdjacentAdaptorPasses();
 
+  // Register all dialects for the current pipeline.
+  DialectRegistry dependent_dialects;
+  getDependentDialects(dependent_dialects);
+  dependent_dialects.loadAll(module.getContext());
+
   // Construct an analysis manager for the pipeline.
   ModuleAnalysisManager am(module, instrumentor.get());
 

diff  --git a/mlir/lib/Pass/PassDetail.h b/mlir/lib/Pass/PassDetail.h
index 2342a1a7af97..f69701d85e15 100644
--- a/mlir/lib/Pass/PassDetail.h
+++ b/mlir/lib/Pass/PassDetail.h
@@ -43,6 +43,10 @@ class OpToOpPassAdaptor
   /// Returns the pass managers held by this adaptor.
   MutableArrayRef<OpPassManager> getPassManagers() { return mgrs; }
 
+  /// Populate the set of dependent dialects for the passes in the current
+  /// adaptor.
+  void getDependentDialects(DialectRegistry &dialects) const override;
+
   /// Return the async pass managers held by this parallel adaptor.
   MutableArrayRef<SmallVector<OpPassManager, 1>> getParallelPassManagers() {
     return asyncExecutors;

diff  --git a/mlir/lib/Support/MlirOptMain.cpp b/mlir/lib/Support/MlirOptMain.cpp
index 25e197083b62..e450fb327f37 100644
--- a/mlir/lib/Support/MlirOptMain.cpp
+++ b/mlir/lib/Support/MlirOptMain.cpp
@@ -75,13 +75,17 @@ static LogicalResult processBuffer(raw_ostream &os,
                                    std::unique_ptr<MemoryBuffer> ownedBuffer,
                                    bool verifyDiagnostics, bool verifyPasses,
                                    bool allowUnregisteredDialects,
+                                   bool preloadDialectsInContext,
                                    const PassPipelineCLParser &passPipeline) {
   // Tell sourceMgr about this buffer, which is what the parser will pick up.
   SourceMgr sourceMgr;
   sourceMgr.AddNewSourceBuffer(std::move(ownedBuffer), SMLoc());
 
   // Parse the input file.
-  MLIRContext context;
+  MLIRContext context(/*loadAllDialects=*/false);
+  registerAllDialects(&context);
+  if (preloadDialectsInContext)
+    context.getDialectRegistry().loadAll(&context);
   context.allowUnregisteredDialects(allowUnregisteredDialects);
   context.printOpOnDiagnostic(!verifyDiagnostics);
 
@@ -111,7 +115,8 @@ LogicalResult mlir::MlirOptMain(raw_ostream &os,
                                 const PassPipelineCLParser &passPipeline,
                                 bool splitInputFile, bool verifyDiagnostics,
                                 bool verifyPasses,
-                                bool allowUnregisteredDialects) {
+                                bool allowUnregisteredDialects,
+                                bool preloadDialectsInContext) {
   // The split-input-file mode is a very specific mode that slices the file
   // up into small pieces and checks each independently.
   if (splitInputFile)
@@ -120,10 +125,11 @@ LogicalResult mlir::MlirOptMain(raw_ostream &os,
         [&](std::unique_ptr<MemoryBuffer> chunkBuffer, raw_ostream &os) {
           return processBuffer(os, std::move(chunkBuffer), verifyDiagnostics,
                                verifyPasses, allowUnregisteredDialects,
-                               passPipeline);
+                               preloadDialectsInContext, passPipeline);
         },
         os);
 
   return processBuffer(os, std::move(buffer), verifyDiagnostics, verifyPasses,
-                       allowUnregisteredDialects, passPipeline);
+                       allowUnregisteredDialects, preloadDialectsInContext,
+                       passPipeline);
 }

diff  --git a/mlir/lib/TableGen/Dialect.cpp b/mlir/lib/TableGen/Dialect.cpp
index 6af77e7df0f6..8aee067d26f7 100644
--- a/mlir/lib/TableGen/Dialect.cpp
+++ b/mlir/lib/TableGen/Dialect.cpp
@@ -16,6 +16,11 @@
 using namespace mlir;
 using namespace mlir::tblgen;
 
+Dialect::Dialect(const llvm::Record *def) : def(def) {
+  for (StringRef dialect : def->getValueAsListOfStrings("dependentDialects"))
+    dependentDialects.push_back(dialect);
+}
+
 StringRef Dialect::getName() const { return def->getValueAsString("name"); }
 
 StringRef Dialect::getCppNamespace() const {
@@ -46,6 +51,10 @@ StringRef Dialect::getDescription() const {
   return getAsStringOrEmpty(*def, "description");
 }
 
+ArrayRef<StringRef> Dialect::getDependentDialects() const {
+  return dependentDialects;
+}
+
 llvm::Optional<StringRef> Dialect::getExtraClassDeclaration() const {
   auto value = def->getValueAsString("extraClassDeclaration");
   return value.empty() ? llvm::Optional<StringRef>() : value;

diff  --git a/mlir/lib/TableGen/Pass.cpp b/mlir/lib/TableGen/Pass.cpp
index 4bc46b622c2b..f96180689c55 100644
--- a/mlir/lib/TableGen/Pass.cpp
+++ b/mlir/lib/TableGen/Pass.cpp
@@ -69,6 +69,8 @@ Pass::Pass(const llvm::Record *def) : def(def) {
     options.push_back(PassOption(init));
   for (auto *init : def->getValueAsListOfDefs("statistics"))
     statistics.push_back(PassStatistic(init));
+  for (StringRef dialect : def->getValueAsListOfStrings("dependentDialects"))
+    dependentDialects.push_back(dialect);
 }
 
 StringRef Pass::getArgument() const {
@@ -88,6 +90,9 @@ StringRef Pass::getDescription() const {
 StringRef Pass::getConstructor() const {
   return def->getValueAsString("constructor");
 }
+ArrayRef<StringRef> Pass::getDependentDialects() const {
+  return dependentDialects;
+}
 
 ArrayRef<PassOption> Pass::getOptions() const { return options; }
 

diff  --git a/mlir/lib/Target/LLVMIR/ConvertFromLLVMIR.cpp b/mlir/lib/Target/LLVMIR/ConvertFromLLVMIR.cpp
index 470044bc9953..1d0156904be3 100644
--- a/mlir/lib/Target/LLVMIR/ConvertFromLLVMIR.cpp
+++ b/mlir/lib/Target/LLVMIR/ConvertFromLLVMIR.cpp
@@ -836,6 +836,7 @@ LogicalResult Importer::processBasicBlock(llvm::BasicBlock *bb, Block *block) {
 OwningModuleRef
 mlir::translateLLVMIRToModule(std::unique_ptr<llvm::Module> llvmModule,
                               MLIRContext *context) {
+  context->getOrLoadDialect<LLVMDialect>();
   OwningModuleRef module(ModuleOp::create(
       FileLineColLoc::get("", /*line=*/0, /*column=*/0, context)));
 

diff  --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index 215c1910f744..027422ba5dc4 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -302,8 +302,7 @@ ModuleTranslation::ModuleTranslation(Operation *module,
     : mlirModule(module), llvmModule(std::move(llvmModule)),
       debugTranslation(
           std::make_unique<DebugTranslation>(module, *this->llvmModule)),
-      ompDialect(
-          module->getContext()->getRegisteredDialect<omp::OpenMPDialect>()),
+      ompDialect(module->getContext()->getOrLoadDialect<omp::OpenMPDialect>()),
       typeTranslator(this->llvmModule->getContext()) {
   assert(satisfiesLLVMModule(mlirModule) &&
          "mlirModule should honor LLVM's module semantics.");
@@ -944,7 +943,7 @@ ModuleTranslation::lookupValues(ValueRange values) {
 
 std::unique_ptr<llvm::Module> ModuleTranslation::prepareLLVMModule(
     Operation *m, llvm::LLVMContext &llvmContext, StringRef name) {
-  auto *dialect = m->getContext()->getRegisteredDialect<LLVM::LLVMDialect>();
+  auto *dialect = m->getContext()->getOrLoadDialect<LLVM::LLVMDialect>();
   assert(dialect && "LLVM dialect must be registered");
 
   auto llvmModule = std::make_unique<llvm::Module>(name, llvmContext);

diff  --git a/mlir/lib/Transforms/PassDetail.h b/mlir/lib/Transforms/PassDetail.h
index c6f7e225d71a..220ed1aac407 100644
--- a/mlir/lib/Transforms/PassDetail.h
+++ b/mlir/lib/Transforms/PassDetail.h
@@ -12,6 +12,13 @@
 #include "mlir/Pass/Pass.h"
 
 namespace mlir {
+// Forward declaration from Dialect.h
+template <typename ConcreteDialect>
+void registerDialect(DialectRegistry &registry);
+
+namespace linalg {
+class LinalgDialect;
+} // end namespace linalg
 
 #define GEN_PASS_CLASSES
 #include "mlir/Transforms/Passes.h.inc"

diff  --git a/mlir/test/CAPI/ir.c b/mlir/test/CAPI/ir.c
index d6ab3513384f..df2d32f7913a 100644
--- a/mlir/test/CAPI/ir.c
+++ b/mlir/test/CAPI/ir.c
@@ -243,6 +243,7 @@ static void printFirstOfEach(MlirOperation operation) {
 int main() {
   mlirRegisterAllDialects();
   MlirContext ctx = mlirContextCreate();
+  mlirContextLoadAllDialects(ctx);
   MlirLocation location = mlirLocationUnknownGet(ctx);
 
   MlirModule moduleOp = makeAdd(ctx, location);

diff  --git a/mlir/test/EDSC/builder-api-test.cpp b/mlir/test/EDSC/builder-api-test.cpp
index 3fcfcf24ef8f..e5766f0bb313 100644
--- a/mlir/test/EDSC/builder-api-test.cpp
+++ b/mlir/test/EDSC/builder-api-test.cpp
@@ -36,16 +36,16 @@ using namespace mlir::edsc;
 using namespace mlir::edsc::intrinsics;
 
 static MLIRContext &globalContext() {
-  static bool init_once = []() {
-    registerDialect<AffineDialect>();
-    registerDialect<linalg::LinalgDialect>();
-    registerDialect<scf::SCFDialect>();
-    registerDialect<StandardOpsDialect>();
-    registerDialect<vector::VectorDialect>();
+  static thread_local MLIRContext context(/*loadAllDialects=*/false);
+  static thread_local bool init_once = [&]() {
+    context.getOrLoadDialect<AffineDialect>();
+    context.getOrLoadDialect<scf::SCFDialect>();
+    context.getOrLoadDialect<linalg::LinalgDialect>();
+    context.getOrLoadDialect<StandardOpsDialect>();
+    context.getOrLoadDialect<vector::VectorDialect>();
     return true;
   }();
   (void)init_once;
-  static thread_local MLIRContext context;
   context.allowUnregisteredDialects();
   return context;
 }

diff  --git a/mlir/test/SDBM/sdbm-api-test.cpp b/mlir/test/SDBM/sdbm-api-test.cpp
index 0b58e2948145..ddefc52fb461 100644
--- a/mlir/test/SDBM/sdbm-api-test.cpp
+++ b/mlir/test/SDBM/sdbm-api-test.cpp
@@ -19,18 +19,19 @@
 
 using namespace mlir;
 
-// Load the SDBM dialect
-static DialectRegistration<SDBMDialect> SDBMRegistration;
 
 static MLIRContext *ctx() {
-  static thread_local MLIRContext context;
+  static thread_local MLIRContext context(/*loadAllDialects=*/false);
+  static thread_local bool once =
+      (context.getOrLoadDialect<SDBMDialect>(), true);
+  (void)once;
   return &context;
 }
 
 static SDBMDialect *dialect() {
   static thread_local SDBMDialect *d = nullptr;
   if (!d) {
-    d = ctx()->getRegisteredDialect<SDBMDialect>();
+    d = ctx()->getOrLoadDialect<SDBMDialect>();
   }
   return d;
 }

diff  --git a/mlir/test/lib/Dialect/Affine/TestVectorizationUtils.cpp b/mlir/test/lib/Dialect/Affine/TestVectorizationUtils.cpp
index a6719b060aac..cfac2dce2300 100644
--- a/mlir/test/lib/Dialect/Affine/TestVectorizationUtils.cpp
+++ b/mlir/test/lib/Dialect/Affine/TestVectorizationUtils.cpp
@@ -14,6 +14,7 @@
 #include "mlir/Analysis/NestedMatcher.h"
 #include "mlir/Analysis/SliceAnalysis.h"
 #include "mlir/Dialect/Affine/IR/AffineOps.h"
+#include "mlir/Dialect/Vector/VectorOps.h"
 #include "mlir/Dialect/Vector/VectorUtils.h"
 #include "mlir/IR/Builders.h"
 #include "mlir/IR/Diagnostics.h"
@@ -72,6 +73,9 @@ struct VectorizerTestPass
     : public PassWrapper<VectorizerTestPass, FunctionPass> {
   static constexpr auto kTestAffineMapOpName = "test_affine_map";
   static constexpr auto kTestAffineMapAttrName = "affine_map";
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<vector::VectorDialect>();
+  }
 
   void runOnFunction() override;
   void testVectorShapeRatio(llvm::raw_ostream &outs);

diff  --git a/mlir/test/lib/Dialect/SPIRV/TestAvailability.cpp b/mlir/test/lib/Dialect/SPIRV/TestAvailability.cpp
index 0c1069f38b67..03c425d6d906 100644
--- a/mlir/test/lib/Dialect/SPIRV/TestAvailability.cpp
+++ b/mlir/test/lib/Dialect/SPIRV/TestAvailability.cpp
@@ -30,7 +30,7 @@ void PrintOpAvailability::runOnFunction() {
   auto f = getFunction();
   llvm::outs() << f.getName() << "\n";
 
-  Dialect *spvDialect = getContext().getRegisteredDialect("spv");
+  Dialect *spvDialect = getContext().getLoadedDialect("spv");
 
   f.getOperation()->walk([&](Operation *op) {
     if (op->getDialect() != spvDialect)

diff  --git a/mlir/test/lib/Dialect/Test/TestPatterns.cpp b/mlir/test/lib/Dialect/Test/TestPatterns.cpp
index f2a17a9f3f5f..be5d799a0253 100644
--- a/mlir/test/lib/Dialect/Test/TestPatterns.cpp
+++ b/mlir/test/lib/Dialect/Test/TestPatterns.cpp
@@ -768,6 +768,10 @@ struct TestTypeConversionProducer
 
 struct TestTypeConversionDriver
     : public PassWrapper<TestTypeConversionDriver, OperationPass<ModuleOp>> {
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<TestDialect>();
+  }
+
   void runOnOperation() override {
     // Initialize the type converter.
     TypeConverter converter;

diff  --git a/mlir/test/lib/Transforms/TestAllReduceLowering.cpp b/mlir/test/lib/Transforms/TestAllReduceLowering.cpp
index c043d0f02f8d..0c72b6cd2a89 100644
--- a/mlir/test/lib/Transforms/TestAllReduceLowering.cpp
+++ b/mlir/test/lib/Transforms/TestAllReduceLowering.cpp
@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "mlir/Dialect/GPU/Passes.h"
+#include "mlir/Dialect/StandardOps/IR/Ops.h"
 #include "mlir/IR/PatternMatch.h"
 #include "mlir/Pass/Pass.h"
 
@@ -19,6 +20,9 @@ using namespace mlir;
 namespace {
 struct TestAllReduceLoweringPass
     : public PassWrapper<TestAllReduceLoweringPass, OperationPass<ModuleOp>> {
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<StandardOpsDialect>();
+  }
   void runOnOperation() override {
     OwningRewritePatternList patterns;
     populateGpuRewritePatterns(&getContext(), patterns);

diff  --git a/mlir/test/lib/Transforms/TestBufferPlacement.cpp b/mlir/test/lib/Transforms/TestBufferPlacement.cpp
index 5ad441aa15c3..6cc0924191cb 100644
--- a/mlir/test/lib/Transforms/TestBufferPlacement.cpp
+++ b/mlir/test/lib/Transforms/TestBufferPlacement.cpp
@@ -116,6 +116,10 @@ struct TestBufferPlacementPreparationPass
     patterns->insert<GenericOpConverter>(context, placer, converter);
   }
 
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<linalg::LinalgDialect>();
+  }
+
   void runOnOperation() override {
     MLIRContext &context = this->getContext();
     ConversionTarget target(context);

diff  --git a/mlir/test/lib/Transforms/TestGpuMemoryPromotion.cpp b/mlir/test/lib/Transforms/TestGpuMemoryPromotion.cpp
index 08862dd06140..339ec1a07a35 100644
--- a/mlir/test/lib/Transforms/TestGpuMemoryPromotion.cpp
+++ b/mlir/test/lib/Transforms/TestGpuMemoryPromotion.cpp
@@ -13,6 +13,9 @@
 
 #include "mlir/Dialect/GPU/GPUDialect.h"
 #include "mlir/Dialect/GPU/MemoryPromotion.h"
+#include "mlir/Dialect/SCF/SCF.h"
+#include "mlir/Dialect/SPIRV/SPIRVDialect.h"
+#include "mlir/Dialect/StandardOps/IR/Ops.h"
 #include "mlir/IR/Attributes.h"
 #include "mlir/Pass/Pass.h"
 
@@ -26,6 +29,11 @@ namespace {
 class TestGpuMemoryPromotionPass
     : public PassWrapper<TestGpuMemoryPromotionPass,
                          OperationPass<gpu::GPUFuncOp>> {
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<StandardOpsDialect>();
+    registry.insert<scf::SCFDialect>();
+  }
+
   void runOnOperation() override {
     gpu::GPUFuncOp op = getOperation();
     for (unsigned i = 0, e = op.getNumArguments(); i < e; ++i) {

diff  --git a/mlir/test/lib/Transforms/TestLinalgHoisting.cpp b/mlir/test/lib/Transforms/TestLinalgHoisting.cpp
index d1e478fec3bc..5d4031f90043 100644
--- a/mlir/test/lib/Transforms/TestLinalgHoisting.cpp
+++ b/mlir/test/lib/Transforms/TestLinalgHoisting.cpp
@@ -10,6 +10,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "mlir/Dialect/Affine/IR/AffineOps.h"
 #include "mlir/Dialect/Linalg/IR/LinalgOps.h"
 #include "mlir/Dialect/Linalg/Transforms/Hoisting.h"
 #include "mlir/Pass/Pass.h"
@@ -22,6 +23,9 @@ struct TestLinalgHoisting
     : public PassWrapper<TestLinalgHoisting, FunctionPass> {
   TestLinalgHoisting() = default;
   TestLinalgHoisting(const TestLinalgHoisting &pass) {}
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<AffineDialect>();
+  }
 
   void runOnFunction() override;
 

diff  --git a/mlir/test/lib/Transforms/TestLinalgTransforms.cpp b/mlir/test/lib/Transforms/TestLinalgTransforms.cpp
index f6c1160d35b0..b6f3cb4eb998 100644
--- a/mlir/test/lib/Transforms/TestLinalgTransforms.cpp
+++ b/mlir/test/lib/Transforms/TestLinalgTransforms.cpp
@@ -15,6 +15,7 @@
 #include "mlir/Dialect/Linalg/IR/LinalgOps.h"
 #include "mlir/Dialect/Linalg/Transforms/Transforms.h"
 #include "mlir/Dialect/Linalg/Utils/Utils.h"
+#include "mlir/Dialect/StandardOps/IR/Ops.h"
 #include "mlir/Dialect/Vector/VectorOps.h"
 #include "mlir/IR/PatternMatch.h"
 #include "mlir/Pass/Pass.h"
@@ -30,6 +31,14 @@ struct TestLinalgTransforms
   TestLinalgTransforms() = default;
   TestLinalgTransforms(const TestLinalgTransforms &pass) {}
 
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<AffineDialect>();
+    registry.insert<scf::SCFDialect>();
+    registry.insert<StandardOpsDialect>();
+    registry.insert<vector::VectorDialect>();
+    registry.insert<gpu::GPUDialect>();
+  }
+
   void runOnFunction() override;
 
   Option<bool> testPatterns{*this, "test-patterns",

diff  --git a/mlir/test/lib/Transforms/TestVectorTransforms.cpp b/mlir/test/lib/Transforms/TestVectorTransforms.cpp
index 9da3156d5359..24e7a8cdae89 100644
--- a/mlir/test/lib/Transforms/TestVectorTransforms.cpp
+++ b/mlir/test/lib/Transforms/TestVectorTransforms.cpp
@@ -8,6 +8,9 @@
 
 #include <type_traits>
 
+#include "mlir/Dialect/Affine/IR/AffineOps.h"
+#include "mlir/Dialect/Linalg/IR/LinalgOps.h"
+#include "mlir/Dialect/SCF/SCF.h"
 #include "mlir/Dialect/StandardOps/IR/Ops.h"
 #include "mlir/Dialect/Vector/VectorOps.h"
 #include "mlir/Dialect/Vector/VectorTransforms.h"
@@ -128,6 +131,13 @@ struct TestVectorTransferFullPartialSplitPatterns
   TestVectorTransferFullPartialSplitPatterns() = default;
   TestVectorTransferFullPartialSplitPatterns(
       const TestVectorTransferFullPartialSplitPatterns &pass) {}
+
+  void getDependentDialects(DialectRegistry &registry) const override {
+    registry.insert<AffineDialect>();
+    registry.insert<linalg::LinalgDialect>();
+    registry.insert<scf::SCFDialect>();
+  }
+
   Option<bool> useLinalgOps{
       *this, "use-linalg-copy",
       llvm::cl::desc("Split using a unmasked vector.transfer + linalg.fill + "

diff  --git a/mlir/test/mlir-opt/commandline.mlir b/mlir/test/mlir-opt/commandline.mlir
index f99a68d6303c..4cf6ea9d8a69 100644
--- a/mlir/test/mlir-opt/commandline.mlir
+++ b/mlir/test/mlir-opt/commandline.mlir
@@ -1,5 +1,5 @@
 // RUN: mlir-opt --show-dialects | FileCheck %s
-// CHECK: Registered Dialects:
+// CHECK: Available Dialects:
 // CHECK: affine
 // CHECK: gpu
 // CHECK: linalg

diff  --git a/mlir/tools/mlir-linalg-ods-gen/mlir-linalg-ods-gen.cpp b/mlir/tools/mlir-linalg-ods-gen/mlir-linalg-ods-gen.cpp
index 12e6aeef9162..92efef67e8f4 100644
--- a/mlir/tools/mlir-linalg-ods-gen/mlir-linalg-ods-gen.cpp
+++ b/mlir/tools/mlir-linalg-ods-gen/mlir-linalg-ods-gen.cpp
@@ -1703,7 +1703,7 @@ int main(int argc, char **argv) {
   if (testEmitIncludeTdHeader)
     output->os() << "include \"mlir/Dialect/Linalg/IR/LinalgStructuredOps.td\"";
 
-  MLIRContext context;
+  MLIRContext context(/*loadAllDialects=*/false);
   llvm::SourceMgr mgr;
   mgr.AddNewSourceBuffer(std::move(file), llvm::SMLoc());
   Parser parser(mgr, &context);

diff  --git a/mlir/tools/mlir-opt/mlir-opt.cpp b/mlir/tools/mlir-opt/mlir-opt.cpp
index efcb32856607..53ea4dae20f7 100644
--- a/mlir/tools/mlir-opt/mlir-opt.cpp
+++ b/mlir/tools/mlir-opt/mlir-opt.cpp
@@ -175,11 +175,10 @@ int main(int argc, char **argv) {
   cl::ParseCommandLineOptions(argc, argv, "MLIR modular optimizer driver\n");
 
   if(showDialects) {
-    llvm::outs() << "Registered Dialects:\n";
-    MLIRContext context;
-    for(Dialect *dialect : context.getRegisteredDialects()) {
-      llvm::outs() << dialect->getNamespace() << "\n";
-    }
+    MLIRContext context(false);
+    registerAllDialects(&context);
+    llvm::outs() << "Available Dialects:\n";
+    interleave(context.getAvailableDialects(), llvm::outs(), "\n");
     return 0;
   }
 

diff  --git a/mlir/tools/mlir-tblgen/DialectGen.cpp b/mlir/tools/mlir-tblgen/DialectGen.cpp
index 13421c42c3c2..797ecd7e2505 100644
--- a/mlir/tools/mlir-tblgen/DialectGen.cpp
+++ b/mlir/tools/mlir-tblgen/DialectGen.cpp
@@ -61,11 +61,14 @@ filterForDialect(ArrayRef<llvm::Record *> records, Dialect &dialect) {
 ///
 /// {0}: The name of the dialect class.
 /// {1}: The dialect namespace.
+/// {2}: initialization code that is emitted in the ctor body before calling
+/// initialize()
 static const char *const dialectDeclBeginStr = R"(
 class {0} : public ::mlir::Dialect {
   explicit {0}(::mlir::MLIRContext *context)
     : ::mlir::Dialect(getDialectNamespace(), context,
       ::mlir::TypeID::get<{0}>()) {{
+    {2}
     initialize();
   }
   void initialize();
@@ -74,6 +77,12 @@ class {0} : public ::mlir::Dialect {
   static ::llvm::StringRef getDialectNamespace() { return "{1}"; }
 )";
 
+/// Registration for a single dependent dialect: to be inserted in the ctor
+/// above for each dependent dialect.
+const char *const dialectRegistrationTemplate = R"(
+    getContext()->getOrLoadDialect<{0}>();
+)";
+
 /// The code block for the attribute parser/printer hooks.
 static const char *const attrParserDecl = R"(
   /// Parse an attribute registered to this dialect.
@@ -136,9 +145,18 @@ static void emitDialectDecl(Dialect &dialect,
                             iterator_range<DialectFilterIterator> dialectAttrs,
                             iterator_range<DialectFilterIterator> dialectTypes,
                             raw_ostream &os) {
+  /// Build the list of dependent dialects
+  std::string dependentDialectRegistrations;
+  {
+    llvm::raw_string_ostream dialects_os(dependentDialectRegistrations);
+    for (StringRef dependentDialect : dialect.getDependentDialects())
+      dialects_os << llvm::formatv(dialectRegistrationTemplate,
+                                   dependentDialect);
+  }
   // Emit the start of the decl.
   std::string cppName = dialect.getCppClassName();
-  os << llvm::formatv(dialectDeclBeginStr, cppName, dialect.getName());
+  os << llvm::formatv(dialectDeclBeginStr, cppName, dialect.getName(),
+                      dependentDialectRegistrations);
 
   // Check for any attributes/types registered to this dialect.  If there are,
   // add the hooks for parsing/printing.

diff  --git a/mlir/tools/mlir-tblgen/PassGen.cpp b/mlir/tools/mlir-tblgen/PassGen.cpp
index c2dcdb8e4ac9..b6f5f3f828eb 100644
--- a/mlir/tools/mlir-tblgen/PassGen.cpp
+++ b/mlir/tools/mlir-tblgen/PassGen.cpp
@@ -36,6 +36,7 @@ static llvm::cl::opt<std::string>
 /// {0}: The def name of the pass record.
 /// {1}: The base class for the pass.
 /// {2): The command line argument for the pass.
+/// {3}: The dependent dialects registration.
 const char *const passDeclBegin = R"(
 //===----------------------------------------------------------------------===//
 // {0}
@@ -63,9 +64,20 @@ class {0}Base : public {1} {
     return std::make_unique<DerivedT>(*static_cast<const DerivedT *>(this));
   }
 
+  /// Return the dialect that must be loaded in the context before this pass.
+  void getDependentDialects(::mlir::DialectRegistry &registry) const override {
+    {3}
+  }
+
 protected:
 )";
 
+/// Registration for a single dependent dialect, to be inserted for each
+/// dependent dialect in the `getDependentDialects` above.
+const char *const dialectRegistrationTemplate = R"(
+  registry.insert<{0}>();
+)";
+
 /// Emit the declarations for each of the pass options.
 static void emitPassOptionDecls(const Pass &pass, raw_ostream &os) {
   for (const PassOption &opt : pass.getOptions()) {
@@ -94,8 +106,15 @@ static void emitPassStatisticDecls(const Pass &pass, raw_ostream &os) {
 
 static void emitPassDecl(const Pass &pass, raw_ostream &os) {
   StringRef defName = pass.getDef()->getName();
+  std::string dependentDialectRegistrations;
+  {
+    llvm::raw_string_ostream dialects_os(dependentDialectRegistrations);
+    for (StringRef dependentDialect : pass.getDependentDialects())
+      dialects_os << llvm::formatv(dialectRegistrationTemplate,
+                                   dependentDialect);
+  }
   os << llvm::formatv(passDeclBegin, defName, pass.getBaseClass(),
-                      pass.getArgument());
+                      pass.getArgument(), dependentDialectRegistrations);
   emitPassOptionDecls(pass, os);
   emitPassStatisticDecls(pass, os);
   os << "};\n";

diff  --git a/mlir/tools/mlir-translate/mlir-translate.cpp b/mlir/tools/mlir-translate/mlir-translate.cpp
index 914bd340b3f5..0d67286a8a91 100644
--- a/mlir/tools/mlir-translate/mlir-translate.cpp
+++ b/mlir/tools/mlir-translate/mlir-translate.cpp
@@ -88,7 +88,8 @@ int main(int argc, char **argv) {
   // Processes the memory buffer with a new MLIRContext.
   auto processBuffer = [&](std::unique_ptr<llvm::MemoryBuffer> ownedBuffer,
                            raw_ostream &os) {
-    MLIRContext context;
+    MLIRContext context(false);
+    registerAllDialects(&context);
     context.allowUnregisteredDialects();
     context.printOpOnDiagnostic(!verifyDiagnostics);
     llvm::SourceMgr sourceMgr;

diff  --git a/mlir/unittests/Dialect/Quant/QuantizationUtilsTest.cpp b/mlir/unittests/Dialect/Quant/QuantizationUtilsTest.cpp
index 97c94a54ffc4..bae95e1a13b6 100644
--- a/mlir/unittests/Dialect/Quant/QuantizationUtilsTest.cpp
+++ b/mlir/unittests/Dialect/Quant/QuantizationUtilsTest.cpp
@@ -17,9 +17,6 @@
 using namespace mlir;
 using namespace mlir::quant;
 
-// Load the quant dialect
-static DialectRegistration<QuantizationDialect> QuantOpsRegistration;
-
 namespace {
 
 // Test UniformQuantizedValueConverter converts all APFloat to a magic number 5.
@@ -78,7 +75,8 @@ UniformQuantizedType getTestQuantizedType(Type storageType, MLIRContext *ctx) {
 }
 
 TEST(QuantizationUtilsTest, convertFloatAttrUniform) {
-  MLIRContext ctx;
+  MLIRContext ctx(/*loadAllDialects=*/false);
+  ctx.getOrLoadDialect<QuantizationDialect>();
   IntegerType convertedType = IntegerType::get(8, &ctx);
   auto quantizedType = getTestQuantizedType(convertedType, &ctx);
   TestUniformQuantizedValueConverter converter(quantizedType);
@@ -95,7 +93,8 @@ TEST(QuantizationUtilsTest, convertFloatAttrUniform) {
 }
 
 TEST(QuantizationUtilsTest, convertRankedDenseAttrUniform) {
-  MLIRContext ctx;
+  MLIRContext ctx(/*loadAllDialects=*/false);
+  ctx.getOrLoadDialect<QuantizationDialect>();
   IntegerType convertedType = IntegerType::get(8, &ctx);
   auto quantizedType = getTestQuantizedType(convertedType, &ctx);
   TestUniformQuantizedValueConverter converter(quantizedType);
@@ -119,7 +118,8 @@ TEST(QuantizationUtilsTest, convertRankedDenseAttrUniform) {
 }
 
 TEST(QuantizationUtilsTest, convertRankedSplatAttrUniform) {
-  MLIRContext ctx;
+  MLIRContext ctx(/*loadAllDialects=*/false);
+  ctx.getOrLoadDialect<QuantizationDialect>();
   IntegerType convertedType = IntegerType::get(8, &ctx);
   auto quantizedType = getTestQuantizedType(convertedType, &ctx);
   TestUniformQuantizedValueConverter converter(quantizedType);
@@ -143,7 +143,8 @@ TEST(QuantizationUtilsTest, convertRankedSplatAttrUniform) {
 }
 
 TEST(QuantizationUtilsTest, convertRankedSparseAttrUniform) {
-  MLIRContext ctx;
+  MLIRContext ctx(/*loadAllDialects=*/false);
+  ctx.getOrLoadDialect<QuantizationDialect>();
   IntegerType convertedType = IntegerType::get(8, &ctx);
   auto quantizedType = getTestQuantizedType(convertedType, &ctx);
   TestUniformQuantizedValueConverter converter(quantizedType);

diff  --git a/mlir/unittests/Dialect/SPIRV/DeserializationTest.cpp b/mlir/unittests/Dialect/SPIRV/DeserializationTest.cpp
index fe5632d7ae16..4aa2ffed7e2b 100644
--- a/mlir/unittests/Dialect/SPIRV/DeserializationTest.cpp
+++ b/mlir/unittests/Dialect/SPIRV/DeserializationTest.cpp
@@ -38,7 +38,8 @@ using ::testing::StrEq;
 /// diagnostic checking utilities.
 class DeserializationTest : public ::testing::Test {
 protected:
-  DeserializationTest() {
+  DeserializationTest() : context(/*loadAllDialects=*/false) {
+    context.getOrLoadDialect<mlir::spirv::SPIRVDialect>();
     // Register a diagnostic handler to capture the diagnostic so that we can
     // check it later.
     context.getDiagEngine().registerHandler([&](Diagnostic &diag) {

diff  --git a/mlir/unittests/Dialect/SPIRV/SerializationTest.cpp b/mlir/unittests/Dialect/SPIRV/SerializationTest.cpp
index 3d57e559ca5e..cb89cd61de7b 100644
--- a/mlir/unittests/Dialect/SPIRV/SerializationTest.cpp
+++ b/mlir/unittests/Dialect/SPIRV/SerializationTest.cpp
@@ -36,7 +36,10 @@ using namespace mlir;
 
 class SerializationTest : public ::testing::Test {
 protected:
-  SerializationTest() { createModuleOp(); }
+  SerializationTest() : context(/*loadAllDialects=*/false) {
+    context.getOrLoadDialect<mlir::spirv::SPIRVDialect>();
+    createModuleOp();
+  }
 
   void createModuleOp() {
     OpBuilder builder(&context);

diff  --git a/mlir/unittests/IR/AttributeTest.cpp b/mlir/unittests/IR/AttributeTest.cpp
index df449a0da75c..78f7dd53d8fd 100644
--- a/mlir/unittests/IR/AttributeTest.cpp
+++ b/mlir/unittests/IR/AttributeTest.cpp
@@ -32,7 +32,7 @@ static void testSplat(Type eltType, const EltTy &splatElt) {
 
 namespace {
 TEST(DenseSplatTest, BoolSplat) {
-  MLIRContext context;
+  MLIRContext context(false);
   IntegerType boolTy = IntegerType::get(1, &context);
   RankedTensorType shape = RankedTensorType::get({2, 2}, boolTy);
 
@@ -57,7 +57,7 @@ TEST(DenseSplatTest, BoolSplat) {
 TEST(DenseSplatTest, LargeBoolSplat) {
   constexpr int64_t boolCount = 56;
 
-  MLIRContext context;
+  MLIRContext context(false);
   IntegerType boolTy = IntegerType::get(1, &context);
   RankedTensorType shape = RankedTensorType::get({boolCount}, boolTy);
 
@@ -80,7 +80,7 @@ TEST(DenseSplatTest, LargeBoolSplat) {
 }
 
 TEST(DenseSplatTest, BoolNonSplat) {
-  MLIRContext context;
+  MLIRContext context(false);
   IntegerType boolTy = IntegerType::get(1, &context);
   RankedTensorType shape = RankedTensorType::get({6}, boolTy);
 
@@ -92,7 +92,7 @@ TEST(DenseSplatTest, BoolNonSplat) {
 
 TEST(DenseSplatTest, OddIntSplat) {
   // Test detecting a splat with an odd(non 8-bit) integer bitwidth.
-  MLIRContext context;
+  MLIRContext context(false);
   constexpr size_t intWidth = 19;
   IntegerType intTy = IntegerType::get(intWidth, &context);
   APInt value(intWidth, 10);
@@ -101,7 +101,7 @@ TEST(DenseSplatTest, OddIntSplat) {
 }
 
 TEST(DenseSplatTest, Int32Splat) {
-  MLIRContext context;
+  MLIRContext context(false);
   IntegerType intTy = IntegerType::get(32, &context);
   int value = 64;
 
@@ -109,7 +109,7 @@ TEST(DenseSplatTest, Int32Splat) {
 }
 
 TEST(DenseSplatTest, IntAttrSplat) {
-  MLIRContext context;
+  MLIRContext context(false);
   IntegerType intTy = IntegerType::get(85, &context);
   Attribute value = IntegerAttr::get(intTy, 109);
 
@@ -117,7 +117,7 @@ TEST(DenseSplatTest, IntAttrSplat) {
 }
 
 TEST(DenseSplatTest, F32Splat) {
-  MLIRContext context;
+  MLIRContext context(false);
   FloatType floatTy = FloatType::getF32(&context);
   float value = 10.0;
 
@@ -125,7 +125,7 @@ TEST(DenseSplatTest, F32Splat) {
 }
 
 TEST(DenseSplatTest, F64Splat) {
-  MLIRContext context;
+  MLIRContext context(false);
   FloatType floatTy = FloatType::getF64(&context);
   double value = 10.0;
 
@@ -133,7 +133,7 @@ TEST(DenseSplatTest, F64Splat) {
 }
 
 TEST(DenseSplatTest, FloatAttrSplat) {
-  MLIRContext context;
+  MLIRContext context(false);
   FloatType floatTy = FloatType::getF32(&context);
   Attribute value = FloatAttr::get(floatTy, 10.0);
 
@@ -141,7 +141,7 @@ TEST(DenseSplatTest, FloatAttrSplat) {
 }
 
 TEST(DenseSplatTest, BF16Splat) {
-  MLIRContext context;
+  MLIRContext context(false);
   FloatType floatTy = FloatType::getBF16(&context);
   Attribute value = FloatAttr::get(floatTy, 10.0);
 
@@ -149,7 +149,7 @@ TEST(DenseSplatTest, BF16Splat) {
 }
 
 TEST(DenseSplatTest, StringSplat) {
-  MLIRContext context;
+  MLIRContext context(false);
   Type stringType =
       OpaqueType::get(Identifier::get("test", &context), "string", &context);
   StringRef value = "test-string";
@@ -157,7 +157,7 @@ TEST(DenseSplatTest, StringSplat) {
 }
 
 TEST(DenseSplatTest, StringAttrSplat) {
-  MLIRContext context;
+  MLIRContext context(false);
   Type stringType =
       OpaqueType::get(Identifier::get("test", &context), "string", &context);
   Attribute stringAttr = StringAttr::get("test-string", stringType);
@@ -165,28 +165,28 @@ TEST(DenseSplatTest, StringAttrSplat) {
 }
 
 TEST(DenseComplexTest, ComplexFloatSplat) {
-  MLIRContext context;
+  MLIRContext context(false);
   ComplexType complexType = ComplexType::get(FloatType::getF32(&context));
   std::complex<float> value(10.0, 15.0);
   testSplat(complexType, value);
 }
 
 TEST(DenseComplexTest, ComplexIntSplat) {
-  MLIRContext context;
+  MLIRContext context(false);
   ComplexType complexType = ComplexType::get(IntegerType::get(64, &context));
   std::complex<int64_t> value(10, 15);
   testSplat(complexType, value);
 }
 
 TEST(DenseComplexTest, ComplexAPFloatSplat) {
-  MLIRContext context;
+  MLIRContext context(false);
   ComplexType complexType = ComplexType::get(FloatType::getF32(&context));
   std::complex<APFloat> value(APFloat(10.0f), APFloat(15.0f));
   testSplat(complexType, value);
 }
 
 TEST(DenseComplexTest, ComplexAPIntSplat) {
-  MLIRContext context;
+  MLIRContext context(false);
   ComplexType complexType = ComplexType::get(IntegerType::get(64, &context));
   std::complex<APInt> value(APInt(64, 10), APInt(64, 15));
   testSplat(complexType, value);

diff  --git a/mlir/unittests/IR/DialectTest.cpp b/mlir/unittests/IR/DialectTest.cpp
index bc389ce1f0da..c43fb77d91d3 100644
--- a/mlir/unittests/IR/DialectTest.cpp
+++ b/mlir/unittests/IR/DialectTest.cpp
@@ -26,12 +26,12 @@ struct AnotherTestDialect : public Dialect {
 };
 
 TEST(DialectDeathTest, MultipleDialectsWithSameNamespace) {
-  MLIRContext context;
+  MLIRContext context(false);
 
   // Registering a dialect with the same namespace twice should result in a
   // failure.
-  context.getOrCreateDialect<TestDialect>();
-  ASSERT_DEATH(context.getOrCreateDialect<AnotherTestDialect>(), "");
+  context.getOrLoadDialect<TestDialect>();
+  ASSERT_DEATH(context.getOrLoadDialect<AnotherTestDialect>(), "");
 }
 
 } // end namespace

diff  --git a/mlir/unittests/IR/OperationSupportTest.cpp b/mlir/unittests/IR/OperationSupportTest.cpp
index 95ddcccc565e..96693309bd13 100644
--- a/mlir/unittests/IR/OperationSupportTest.cpp
+++ b/mlir/unittests/IR/OperationSupportTest.cpp
@@ -25,7 +25,7 @@ static Operation *createOp(MLIRContext *context,
 
 namespace {
 TEST(OperandStorageTest, NonResizable) {
-  MLIRContext context;
+  MLIRContext context(false);
   Builder builder(&context);
 
   Operation *useOp =
@@ -49,7 +49,7 @@ TEST(OperandStorageTest, NonResizable) {
 }
 
 TEST(OperandStorageTest, Resizable) {
-  MLIRContext context;
+  MLIRContext context(false);
   Builder builder(&context);
 
   Operation *useOp =
@@ -77,7 +77,7 @@ TEST(OperandStorageTest, Resizable) {
 }
 
 TEST(OperandStorageTest, RangeReplace) {
-  MLIRContext context;
+  MLIRContext context(false);
   Builder builder(&context);
 
   Operation *useOp =
@@ -113,7 +113,7 @@ TEST(OperandStorageTest, RangeReplace) {
 }
 
 TEST(OperandStorageTest, MutableRange) {
-  MLIRContext context;
+  MLIRContext context(false);
   Builder builder(&context);
 
   Operation *useOp =

diff  --git a/mlir/unittests/Pass/AnalysisManagerTest.cpp b/mlir/unittests/Pass/AnalysisManagerTest.cpp
index a99df3911a5d..958cf43b209d 100644
--- a/mlir/unittests/Pass/AnalysisManagerTest.cpp
+++ b/mlir/unittests/Pass/AnalysisManagerTest.cpp
@@ -24,7 +24,7 @@ struct OtherAnalysis {
 };
 
 TEST(AnalysisManagerTest, FineGrainModuleAnalysisPreservation) {
-  MLIRContext context;
+  MLIRContext context(false);
 
   // Test fine grain invalidation of the module analysis manager.
   OwningModuleRef module(ModuleOp::create(UnknownLoc::get(&context)));
@@ -45,7 +45,7 @@ TEST(AnalysisManagerTest, FineGrainModuleAnalysisPreservation) {
 }
 
 TEST(AnalysisManagerTest, FineGrainFunctionAnalysisPreservation) {
-  MLIRContext context;
+  MLIRContext context(false);
   Builder builder(&context);
 
   // Create a function and a module.
@@ -74,7 +74,7 @@ TEST(AnalysisManagerTest, FineGrainFunctionAnalysisPreservation) {
 }
 
 TEST(AnalysisManagerTest, FineGrainChildFunctionAnalysisPreservation) {
-  MLIRContext context;
+  MLIRContext context(false);
   Builder builder(&context);
 
   // Create a function and a module.
@@ -117,7 +117,7 @@ struct CustomInvalidatingAnalysis {
 };
 
 TEST(AnalysisManagerTest, CustomInvalidation) {
-  MLIRContext context;
+  MLIRContext context(false);
   Builder builder(&context);
 
   // Create a function and a module.

diff  --git a/mlir/unittests/SDBM/SDBMTest.cpp b/mlir/unittests/SDBM/SDBMTest.cpp
index 61d670650b4b..bbe87e3d292c 100644
--- a/mlir/unittests/SDBM/SDBMTest.cpp
+++ b/mlir/unittests/SDBM/SDBMTest.cpp
@@ -17,18 +17,17 @@
 
 using namespace mlir;
 
-/// Load the SDBM dialect.
-static DialectRegistration<SDBMDialect> SDBMRegistration;
 
 static MLIRContext *ctx() {
-  static thread_local MLIRContext context;
+  static thread_local MLIRContext context(false);
+  context.getOrLoadDialect<SDBMDialect>();
   return &context;
 }
 
 static SDBMDialect *dialect() {
   static thread_local SDBMDialect *d = nullptr;
   if (!d) {
-    d = ctx()->getRegisteredDialect<SDBMDialect>();
+    d = ctx()->getOrLoadDialect<SDBMDialect>();
   }
   return d;
 }

diff  --git a/mlir/unittests/TableGen/OpBuildGen.cpp b/mlir/unittests/TableGen/OpBuildGen.cpp
index 3e3256e96cd0..46a37da6e944 100644
--- a/mlir/unittests/TableGen/OpBuildGen.cpp
+++ b/mlir/unittests/TableGen/OpBuildGen.cpp
@@ -25,11 +25,16 @@ namespace mlir {
 // Test Fixture
 //===----------------------------------------------------------------------===//
 
+static MLIRContext &getContext() {
+  static MLIRContext ctx(false);
+  ctx.getOrLoadDialect<TestDialect>();
+  return ctx;
+}
 /// Test fixture for providing basic utilities for testing.
 class OpBuildGenTest : public ::testing::Test {
 protected:
   OpBuildGenTest()
-      : ctx{}, builder(&ctx), loc(builder.getUnknownLoc()),
+      : ctx(getContext()), builder(&ctx), loc(builder.getUnknownLoc()),
         i32Ty(builder.getI32Type()), f32Ty(builder.getF32Type()),
         cstI32(builder.create<TableGenConstant>(loc, i32Ty)),
         cstF32(builder.create<TableGenConstant>(loc, f32Ty)),
@@ -86,7 +91,7 @@ class OpBuildGenTest : public ::testing::Test {
   }
 
 protected:
-  MLIRContext ctx;
+  MLIRContext &ctx;
   OpBuilder builder;
   Location loc;
   Type i32Ty;

diff  --git a/mlir/unittests/TableGen/StructsGenTest.cpp b/mlir/unittests/TableGen/StructsGenTest.cpp
index c58fedb4ec4f..14b0abc675bf 100644
--- a/mlir/unittests/TableGen/StructsGenTest.cpp
+++ b/mlir/unittests/TableGen/StructsGenTest.cpp
@@ -42,7 +42,7 @@ static test::TestStruct getTestStruct(mlir::MLIRContext *context) {
 /// Validates that test::TestStruct::classof correctly identifies a valid
 /// test::TestStruct.
 TEST(StructsGenTest, ClassofTrue) {
-  mlir::MLIRContext context;
+  mlir::MLIRContext context(false);
   auto structAttr = getTestStruct(&context);
   ASSERT_TRUE(test::TestStruct::classof(structAttr));
 }


        


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