[PATCH] D77314: [mlir][LLVM] Finer-grained control for C interface emission

[Nicolas Vasilache via Phabricator via llvm-commits]

nicolasvasilache updated this revision to Diff 254554.
nicolasvasilache added a comment.

Drop spurious formatting.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D77314/new/

https://reviews.llvm.org/D77314

Files:
  mlir/docs/ConversionToLLVMDialect.md
  mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp
  mlir/test/Conversion/StandardToLLVM/calling-convention.mlir


Index: mlir/test/Conversion/StandardToLLVM/calling-convention.mlir
===================================================================
--- mlir/test/Conversion/StandardToLLVM/calling-convention.mlir
+++ mlir/test/Conversion/StandardToLLVM/calling-convention.mlir
@@ -1,4 +1,5 @@
 // RUN: mlir-opt -convert-std-to-llvm='emit-c-wrappers=1' %s | FileCheck %s
+// RUN: mlir-opt -convert-std-to-llvm %s | FileCheck %s --check-prefix=EMIT_C_ATTRIBUTE
 
 // This tests the default memref calling convention and the emission of C
 // wrappers. We don't need to separate runs because the wrapper-emission
@@ -72,6 +73,7 @@
 }
 
 // CHECK-LABEL: @callee
+// EMIT_C_ATTRIBUTE-LABEL: @callee
 func @callee(%arg0: memref<?xf32>, %arg1: index) {
   %0 = load %arg0[%arg1] : memref<?xf32>
   return
@@ -93,3 +95,17 @@
   // Forward the descriptor components to the call.
   // CHECK: llvm.call @callee(%[[ALLOC]], %[[ALIGN]], %[[OFFSET]], %[[SIZE]], %[[STRIDE]], %{{.*}}) : (!llvm<"float*">, !llvm<"float*">, !llvm.i64, !llvm.i64, !llvm.i64, !llvm.i64) -> ()
 
+//   EMIT_C_ATTRIBUTE-NOT: @mlir_ciface_callee
+
+// CHECK-LABEL: @other_callee
+// EMIT_C_ATTRIBUTE-LABEL: @other_callee
+func @other_callee(%arg0: memref<?xf32>, %arg1: index) attributes { llvm.emit_c_interface } {
+  %0 = load %arg0[%arg1] : memref<?xf32>
+  return
+}
+
+// CHECK: @_mlir_ciface_other_callee
+// CHECK:   llvm.call @other_callee
+
+// EMIT_C_ATTRIBUTE: @_mlir_ciface_other_callee
+// EMIT_C_ATTRIBUTE:   llvm.call @other_callee
Index: mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp
===================================================================
--- mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp
+++ mlir/lib/Conversion/StandardToLLVM/StandardToLLVM.cpp
@@ -932,6 +932,7 @@
 /// FuncOp legalization pattern that converts MemRef arguments to pointers to
 /// MemRef descriptors (LLVM struct data types) containing all the MemRef type
 /// information.
+static constexpr StringRef kEmitIfaceAttrName = "llvm.emit_c_interface";
 struct FuncOpConversion : public FuncOpConversionBase {
   FuncOpConversion(LLVMTypeConverter &converter, bool emitCWrappers)
       : FuncOpConversionBase(converter), emitWrappers(emitCWrappers) {}
@@ -942,7 +943,7 @@
     auto funcOp = cast<FuncOp>(op);
 
     auto newFuncOp = convertFuncOpToLLVMFuncOp(funcOp, rewriter);
-    if (emitWrappers) {
+    if (emitWrappers || funcOp.getAttrOfType<UnitAttr>(kEmitIfaceAttrName)) {
       if (newFuncOp.isExternal())
         wrapExternalFunction(rewriter, op->getLoc(), typeConverter, funcOp,
                              newFuncOp);
@@ -2843,7 +2844,6 @@
     if (failed(applyPartialConversion(m, target, patterns, &typeConverter)))
       signalPassFailure();
   }
-
 };
 } // end namespace
 
Index: mlir/docs/ConversionToLLVMDialect.md
===================================================================
--- mlir/docs/ConversionToLLVMDialect.md
+++ mlir/docs/ConversionToLLVMDialect.md
@@ -374,12 +374,14 @@
 
 ### C-compatible wrapper emission
 
-In practical cases, it may be desirable to have externally-facing functions
-with a single attribute corresponding to a MemRef argument. When interfacing
-with LLVM IR produced from C, the code needs to respect the corresponding
-calling convention. The conversion to the LLVM dialect provides an option to
-generate wrapper functions that take memref descriptors as pointers-to-struct
-compatible with data types produced by Clang when compiling C sources.
+In practical cases, it may be desirable to have externally-facing functions with
+a single attribute corresponding to a MemRef argument. When interfacing with
+LLVM IR produced from C, the code needs to respect the corresponding calling
+convention. The conversion to the LLVM dialect provides an option to generate
+wrapper functions that take memref descriptors as pointers-to-struct compatible
+with data types produced by Clang when compiling C sources. The generation of
+such wrapper functions can additionally be controlled at a function granularity
+by setting the `llvm.emit_c_interface` unit attribute.
 
 More specifically, a memref argument is converted into a pointer-to-struct
 argument of type `{T*, T*, i64, i64[N], i64[N]}*` in the wrapper function, where


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