[OMPIRBuilder] Propagate attributes to outlined target regions (llvm#117875)

This patch copies the target-cpu and target-features attributes of
functions containing target regions into the corresponding outlined
function holding the target region.

This mirrors what is currently being done for all other outlined
functions through the `CodeExtractor` in `OpenMPIRBuilder::finalize()`.

Author: skatrak

llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp

@@ -6774,6 +6774,18 @@ static Expected<Function *> createOutlinedFunction(
   auto Func =
       Function::Create(FuncType, GlobalValue::InternalLinkage, FuncName, M);
 
+  // Forward target-cpu and target-features function attributes from the
+  // original function to the new outlined function.
+  Function *ParentFn = Builder.GetInsertBlock()->getParent();
+
+  auto TargetCpuAttr = ParentFn->getFnAttribute("target-cpu");
+  if (TargetCpuAttr.isStringAttribute())
+    Func->addFnAttr(TargetCpuAttr);
+
+  auto TargetFeaturesAttr = ParentFn->getFnAttribute("target-features");
+  if (TargetFeaturesAttr.isStringAttribute())
+    Func->addFnAttr(TargetFeaturesAttr);
+
   if (OMPBuilder.Config.isTargetDevice()) {
     Value *ExecMode =
         OMPBuilder.emitKernelExecutionMode(FuncName, DefaultAttrs.ExecFlags);

llvm/unittests/Frontend/OpenMPIRBuilderTest.cpp

@@ -6169,6 +6169,8 @@ TEST_F(OpenMPIRBuilderTest, TargetRegion) {
   OpenMPIRBuilderConfig Config(false, false, false, false, false, false, false);
   OMPBuilder.setConfig(Config);
   F->setName("func");
+  F->addFnAttr("target-cpu", "x86-64");
+  F->addFnAttr("target-features", "+mmx,+sse");
   IRBuilder<> Builder(BB);
   auto *Int32Ty = Builder.getInt32Ty();
 
@@ -6320,6 +6322,13 @@ TEST_F(OpenMPIRBuilderTest, TargetRegion) {
   StringRef FunctionName2 = OutlinedFunc->getName();
   EXPECT_TRUE(FunctionName2.starts_with("__omp_offloading"));
 
+  // Check that target-cpu and target-features were propagated to the outlined
+  // function
+  EXPECT_EQ(OutlinedFunc->getFnAttribute("target-cpu"),
+            F->getFnAttribute("target-cpu"));
+  EXPECT_EQ(OutlinedFunc->getFnAttribute("target-features"),
+            F->getFnAttribute("target-features"));
+
   EXPECT_FALSE(verifyModule(*M, &errs()));
 }
 
@@ -6330,6 +6339,8 @@ TEST_F(OpenMPIRBuilderTest, TargetRegionDevice) {
   OMPBuilder.initialize();
 
   F->setName("func");
+  F->addFnAttr("target-cpu", "gfx90a");
+  F->addFnAttr("target-features", "+gfx9-insts,+wavefrontsize64");
   IRBuilder<> Builder(BB);
   OpenMPIRBuilder::LocationDescription Loc({Builder.saveIP(), DL});
 
@@ -6407,6 +6418,13 @@ TEST_F(OpenMPIRBuilderTest, TargetRegionDevice) {
   Function *OutlinedFn = TargetStore->getFunction();
   EXPECT_NE(F, OutlinedFn);
 
+  // Check that target-cpu and target-features were propagated to the outlined
+  // function
+  EXPECT_EQ(OutlinedFn->getFnAttribute("target-cpu"),
+            F->getFnAttribute("target-cpu"));
+  EXPECT_EQ(OutlinedFn->getFnAttribute("target-features"),
+            F->getFnAttribute("target-features"));
+
   EXPECT_TRUE(OutlinedFn->hasWeakODRLinkage());
   // Account for the "implicit" first argument.
   EXPECT_EQ(OutlinedFn->getName(), "__omp_offloading_1_2_parent_l3");
@@ -6657,6 +6675,13 @@ TEST_F(OpenMPIRBuilderTest, TargetRegionDeviceSPMD) {
   EXPECT_NE(OutlinedFn, nullptr);
   EXPECT_NE(F, OutlinedFn);
 
+  // Check that target-cpu and target-features were propagated to the outlined
+  // function
+  EXPECT_EQ(OutlinedFn->getFnAttribute("target-cpu"),
+            F->getFnAttribute("target-cpu"));
+  EXPECT_EQ(OutlinedFn->getFnAttribute("target-features"),
+            F->getFnAttribute("target-features"));
+
   EXPECT_TRUE(OutlinedFn->hasWeakODRLinkage());
   // Account for the "implicit" first argument.
   EXPECT_EQ(OutlinedFn->getName(), "__omp_offloading_1_2_parent_l3");