[flang] [clang] Revert "[flang] Enable alias tags pass by default (#73111)" (PR #73821)

via cfe-commits cfe-commits at lists.llvm.org
Wed Nov 29 09:07:39 PST 2023


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-driver

Author: Tom Eccles (tblah)

<details>
<summary>Changes</summary>

This reverts commit caba0314cf631a3ba3e982cbcdc455224046c7a8.

Serious performance regressions were reported by @<!-- -->vzakhari https://github.com/llvm/llvm-project/issues/58303#issuecomment-1830754173

Fixing this doesn't look quick so I will revert for now.

---
Full diff: https://github.com/llvm/llvm-project/pull/73821.diff


8 Files Affected:

- (modified) clang/lib/Driver/ToolChains/Flang.cpp (-20) 
- (modified) flang/include/flang/Tools/CLOptions.inc (+3-3) 
- (modified) flang/lib/Frontend/CompilerInvocation.cpp (+4-6) 
- (modified) flang/test/Driver/falias-analysis.f90 (+1-15) 
- (modified) flang/test/Driver/mlir-pass-pipeline.f90 (-2) 
- (modified) flang/test/Driver/optimization-remark.f90 (+13-9) 
- (modified) flang/test/Fir/basic-program.fir (-4) 
- (modified) flang/tools/tco/tco.cpp (-1) 


``````````diff
diff --git a/clang/lib/Driver/ToolChains/Flang.cpp b/clang/lib/Driver/ToolChains/Flang.cpp
index 86e1c57e485685e..01f07b9228256cf 100644
--- a/clang/lib/Driver/ToolChains/Flang.cpp
+++ b/clang/lib/Driver/ToolChains/Flang.cpp
@@ -142,26 +142,6 @@ void Flang::addCodegenOptions(const ArgList &Args,
   if (shouldLoopVersion(Args))
     CmdArgs.push_back("-fversion-loops-for-stride");
 
-  Arg *aliasAnalysis = Args.getLastArg(options::OPT_falias_analysis,
-                                       options::OPT_fno_alias_analysis);
-  // only pass on the argument if it does not match that implied by the
-  // optimization level: so if optimization is requested, only forward
-  // -fno-alias-analysis. If optimization is not requested, only forward
-  // -falias-analysis.
-  Arg *optLevel =
-      Args.getLastArg(options::OPT_Ofast, options::OPT_O, options::OPT_O4);
-  if (aliasAnalysis) {
-    bool faliasAnalysis =
-        aliasAnalysis->getOption().matches(options::OPT_falias_analysis);
-    if (optLevel && !faliasAnalysis) {
-      CmdArgs.push_back("-fno-alias-analysis");
-    } else {
-      if (faliasAnalysis)
-        // requested alias analysis but no optimization enabled
-        CmdArgs.push_back("-falias-analysis");
-    }
-  }
-
   Args.addAllArgs(CmdArgs, {options::OPT_flang_experimental_hlfir,
                             options::OPT_flang_deprecated_no_hlfir,
                             options::OPT_flang_experimental_polymorphism,
diff --git a/flang/include/flang/Tools/CLOptions.inc b/flang/include/flang/Tools/CLOptions.inc
index d3e4dc6cd4a243e..c452c023b4a80ce 100644
--- a/flang/include/flang/Tools/CLOptions.inc
+++ b/flang/include/flang/Tools/CLOptions.inc
@@ -158,10 +158,10 @@ inline void addDebugFoundationPass(mlir::PassManager &pm) {
 }
 
 inline void addFIRToLLVMPass(
-    mlir::PassManager &pm, const MLIRToLLVMPassPipelineConfig &config) {
+    mlir::PassManager &pm, llvm::OptimizationLevel optLevel = defaultOptLevel) {
   fir::FIRToLLVMPassOptions options;
   options.ignoreMissingTypeDescriptors = ignoreMissingTypeDescriptors;
-  options.applyTBAA = config.AliasAnalysis;
+  options.applyTBAA = optLevel.isOptimizingForSpeed();
   options.forceUnifiedTBAATree = useOldAliasTags;
   addPassConditionally(pm, disableFirToLlvmIr,
       [&]() { return fir::createFIRToLLVMPass(options); });
@@ -311,7 +311,7 @@ inline void createDefaultFIRCodeGenPassPipeline(
   if (config.VScaleMin != 0)
     pm.addPass(fir::createVScaleAttrPass({config.VScaleMin, config.VScaleMax}));
 
-  fir::addFIRToLLVMPass(pm, config);
+  fir::addFIRToLLVMPass(pm, config.OptLevel);
 }
 
 /// Create a pass pipeline for lowering from MLIR to LLVM IR
diff --git a/flang/lib/Frontend/CompilerInvocation.cpp b/flang/lib/Frontend/CompilerInvocation.cpp
index 1c09ae9c281eb47..cb4f2d6a6225205 100644
--- a/flang/lib/Frontend/CompilerInvocation.cpp
+++ b/flang/lib/Frontend/CompilerInvocation.cpp
@@ -242,12 +242,10 @@ static void parseCodeGenArgs(Fortran::frontend::CodeGenOptions &opts,
                    clang::driver::options::OPT_fno_loop_versioning, false))
     opts.LoopVersioning = 1;
 
-  opts.AliasAnalysis = opts.OptimizationLevel > 0;
-  if (auto *arg =
-          args.getLastArg(clang::driver::options::OPT_falias_analysis,
-                          clang::driver::options::OPT_fno_alias_analysis))
-    opts.AliasAnalysis =
-        arg->getOption().matches(clang::driver::options::OPT_falias_analysis);
+  opts.AliasAnalysis =
+      args.hasFlag(clang::driver::options::OPT_falias_analysis,
+                   clang::driver::options::OPT_fno_alias_analysis,
+                   /*default=*/false);
 
   for (auto *a : args.filtered(clang::driver::options::OPT_fpass_plugin_EQ))
     opts.LLVMPassPlugins.push_back(a->getValue());
diff --git a/flang/test/Driver/falias-analysis.f90 b/flang/test/Driver/falias-analysis.f90
index 3bd389c33dbc578..f2c5dbde6d2c878 100644
--- a/flang/test/Driver/falias-analysis.f90
+++ b/flang/test/Driver/falias-analysis.f90
@@ -2,26 +2,12 @@
 ! See flang/test/Fir/tbaa-codegen.fir for a test that the output is correct
 
 ! RUN: %flang -c -emit-llvm -falias-analysis %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
-! RUN: %flang -c -emit-llvm -Ofast %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
-! RUN: %flang -c -emit-llvm -O3 %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
-! RUN: %flang -c -emit-llvm -O2 %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
-! RUN: %flang -c -emit-llvm -O1 %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
-
-! RUN: %flang -c -emit-llvm -O0 %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
-! RUN: %flang -c -emit-llvm -Ofast -fno-alias-analysis %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
-! RUN: %flang -c -emit-llvm -fno-alias-analysis -Ofast %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
-! RUN: %flang -c -emit-llvm %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
 ! RUN: %flang -c -emit-llvm -falias-analysis -fno-alias-analysis %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
+! RUN: %flang -c -emit-llvm %s -o - | llvm-dis | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
 
 ! RUN: %flang -fc1 -emit-llvm -falias-analysis %s -o - | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
-! RUN: %flang -fc1 -emit-llvm -O3 %s -o - | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
-! RUN: %flang -fc1 -emit-llvm -O2 %s -o - | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
-! RUN: %flang -fc1 -emit-llvm -O1 %s -o - | FileCheck %s --check-prefix=CHECK-AA --check-prefix=CHECK-ALL
-
-! RUN: %flang -fc1 -emit-llvm -O0 %s -o - | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
 ! RUN: %flang -fc1 -emit-llvm -falias-analysis -fno-alias-analysis %s -o - | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
 ! RUN: %flang -fc1 -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
-! RUN: %flang -fc1 -emit-llvm -O3 -fno-alias-analysis %s -o - | FileCheck %s --check-prefix=CHECK-NOAA --check-prefix=CHECK-ALL
 
 subroutine simple(a)
   integer, intent(inout) :: a(:)
diff --git a/flang/test/Driver/mlir-pass-pipeline.f90 b/flang/test/Driver/mlir-pass-pipeline.f90
index 3d8c42f123e2eb0..7f92ec25bef98ec 100644
--- a/flang/test/Driver/mlir-pass-pipeline.f90
+++ b/flang/test/Driver/mlir-pass-pipeline.f90
@@ -51,8 +51,6 @@
 
 ! ALL-NEXT: 'func.func' Pipeline
 ! ALL-NEXT:   PolymorphicOpConversion
-! O2-NEXT:  AddAliasTags
-! O2-NEXT:  'func.func' Pipeline
 ! ALL-NEXT:   CFGConversion
 
 ! ALL-NEXT: SCFToControlFlow
diff --git a/flang/test/Driver/optimization-remark.f90 b/flang/test/Driver/optimization-remark.f90
index 20ff9eb59a6702d..13fc24346eac68b 100644
--- a/flang/test/Driver/optimization-remark.f90
+++ b/flang/test/Driver/optimization-remark.f90
@@ -41,24 +41,28 @@
 ! Once we start filtering, this is reduced to 1 one of the loop passes.
 
 ! PASS-REGEX-LOOP-ONLY-NOT:     optimization-remark.f90:77:7: remark: hoisting load [-Rpass=licm]
-! PASS-REGEX-LOOP-ONLY:         optimization-remark.f90:79:5: remark: Loop deleted because it is invariant [-Rpass=loop-delete]
+! PASS-REGEX-LOOP-ONLY:         optimization-remark.f90:83:5: remark: Loop deleted because it is invariant [-Rpass=loop-delete]
 
 ! MISSED-REGEX-LOOP-ONLY-NOT:   optimization-remark.f90:77:7: remark: failed to hoist load with loop-invariant address because load is conditionally executed [-Rpass-missed=licm]
-! MISSED-REGEX-LOOP-ONLY:       optimization-remark.f90:72:4: remark: loop not vectorized [-Rpass-missed=loop-vectorize]
+! MISSED-REGEX-LOOP-ONLY:       optimization-remark.f90:76:4: remark: loop not vectorized [-Rpass-missed=loop-vectorize]
 
 
-! ANALYSIS-REGEX-LOOP-ONLY:     optimization-remark.f90:73:7: remark: loop not vectorized: cannot identify array bounds [-Rpass-analysis=loop-vectorize]
+! ANALYSIS-REGEX-LOOP-ONLY:     optimization-remark.f90:79:7: remark: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+! ANALYSIS-REGEX-LOOP-ONLY:     Unknown data dependence. Memory location is the same as accessed at optimization-remark.f90:78:7 [-Rpass-analysis=loop-vectorize]
 ! ANALYSIS-REGEX-LOOP-ONLY-NOT: remark: {{.*}}: IR instruction count changed from {{[0-9]+}} to {{[0-9]+}}; Delta: {{-?[0-9]+}} [-Rpass-analysis=size-info]
 
-! PASS:                         optimization-remark.f90:79:5: remark: Loop deleted because it is invariant [-Rpass=loop-delete]
+! PASS:                         optimization-remark.f90:77:7: remark: hoisting load [-Rpass=licm]
+! PASS:                         optimization-remark.f90:83:5: remark: Loop deleted because it is invariant [-Rpass=loop-delete]
 
-! MISSED:                       optimization-remark.f90:73:7: remark: failed to move load with loop-invariant address because the loop may invalidate its value [-Rpass-missed=licm]
-! MISSED:                       optimization-remark.f90:72:4: remark: loop not vectorized [-Rpass-missed=loop-vectorize]
-! MISSED-NOT:                   optimization-remark.f90:75:7: remark: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+! MISSED:                       optimization-remark.f90:77:7: remark: failed to hoist load with loop-invariant address because load is conditionally executed [-Rpass-missed=licm]
+! MISSED:                       optimization-remark.f90:76:4: remark: loop not vectorized [-Rpass-missed=loop-vectorize]
+! MISSED-NOT:                   optimization-remark.f90:79:7: remark: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
 ! MISSED-NOT:                   Unknown data dependence. Memory location is the same as accessed at optimization-remark.f90:78:7 [-Rpass-analysis=loop-vectorize]
 
-! ANALYSIS:                     optimization-remark.f90:74:7: remark: loop not vectorized: unsafe dependent memory operations in loop.
-! ANALYSIS:                     remark: {{.*}} instructions in function [-Rpass-analysis=asm-printer]
+! ANALYSIS:                     optimization-remark.f90:79:7: remark: loop not vectorized: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+! ANALYSIS:                     Unknown data dependence. Memory location is the same as accessed at optimization-remark.f90:78:7 [-Rpass-analysis=loop-vectorize]
+! ANALYSIS:                     remark: {{.*}}: IR instruction count changed from {{[0-9]+}} to {{[0-9]+}}; Delta: {{-?[0-9]+}} [-Rpass-analysis=size-info]
+! ANALYSIS-NOT:                 optimization-remark.f90:77:7: remark: failed to hoist load with loop-invariant address because load is conditionally executed [-Rpass-missed=licm]
 
 subroutine swap_real(a1, a2)
    implicit none
diff --git a/flang/test/Fir/basic-program.fir b/flang/test/Fir/basic-program.fir
index d8a9e74c318ce18..0e82f7dfdedb447 100644
--- a/flang/test/Fir/basic-program.fir
+++ b/flang/test/Fir/basic-program.fir
@@ -57,10 +57,6 @@ func.func @_QQmain() {
 
 // PASSES-NEXT: 'func.func' Pipeline
 // PASSES-NEXT:   PolymorphicOpConversion
-
-// PASSES-NEXT: AddAliasTags
-
-// PASSES-NEXT: 'func.func' Pipeline
 // PASSES-NEXT:   CFGConversion
 
 // PASSES-NEXT: SCFToControlFlow
diff --git a/flang/tools/tco/tco.cpp b/flang/tools/tco/tco.cpp
index a649535a39b74b3..31d6bac142dc421 100644
--- a/flang/tools/tco/tco.cpp
+++ b/flang/tools/tco/tco.cpp
@@ -120,7 +120,6 @@ compileFIR(const mlir::PassPipelineCLParser &passPipeline) {
       return mlir::failure();
   } else {
     MLIRToLLVMPassPipelineConfig config(llvm::OptimizationLevel::O2);
-    config.AliasAnalysis = true; // enabled when optimizing for speed
     if (codeGenLLVM) {
       // Run only CodeGen passes.
       fir::createDefaultFIRCodeGenPassPipeline(pm, config);

``````````

</details>


https://github.com/llvm/llvm-project/pull/73821


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