[PATCH] D148906: [AMDGPU] Remove incompatible attributes of function in amdgpu-remove-incompatible-functions pass

[krishna chaitanya sankisa via Phabricator via llvm-commits]

skc7 created this revision.
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Enable removeInvalidAttributes method to remove any incompatible attributes to the function.
Currently, wavfrontsize32 is being appended by device-libs to some functions for gfx9 targets.
This change checks and removes "wavefrontsize32" attribute for gfx10 below targets.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D148906

Files:
  llvm/lib/Target/AMDGPU/AMDGPURemoveIncompatibleFunctions.cpp
  llvm/test/CodeGen/AMDGPU/remove-incompatible-attributes.ll


Index: llvm/test/CodeGen/AMDGPU/remove-incompatible-attributes.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AMDGPU/remove-incompatible-attributes.ll
@@ -0,0 +1,34 @@
+; RUN: llc -march=amdgcn -mcpu=gfx90a -mattr=+wavefrontsize64 -stop-after=amdgpu-remove-incompatible-functions < %s | FileCheck -check-prefix=GFX90A %s
+
+; Check if wavefrontsize32 attribute is removed after the pass
+define void @test1(ptr %out) #0 {
+  %1 = tail call i32 @llvm.read_register.i32(metadata !0)
+  %2 = tail call i32 @llvm.ctpop.i32(i32 %1)
+  store i32 %2, ptr %out, align 4
+  ret void
+}
+
+; Check that pass doesn't cause issue with other target-features
+define amdgpu_kernel void @test2() #1 {
+  ret void
+}
+
+; Check if wavefrontsize32 attribute is removed but not the other target-features after the pass
+define amdgpu_kernel void @test3() #2 {
+  ret void
+}
+
+declare i32 @llvm.read_register.i32(metadata)
+declare i32 @llvm.ctpop.i32(i32)
+
+!0 = !{!"exec_lo"}
+
+; GFX90A: @test1(ptr %out) #0
+; GFX90A: @test2() #1
+; GFX90A: @test3() #1
+; GFX90A: attributes #0 = { "target-cpu"="gfx90a" "target-features"="+wavefrontsize64" }
+; GFX90A: attributes #1 = { "target-cpu"="gfx90a" "target-features"="+xnack,+wavefrontsize64" }
+
+attributes #0 = { "target-features"="+wavefrontsize32" }
+attributes #1 = { "target-features"="+xnack" }
+attributes #2 = { "target-features"="+wavefrontsize32,+xnack" }
Index: llvm/lib/Target/AMDGPU/AMDGPURemoveIncompatibleFunctions.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPURemoveIncompatibleFunctions.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPURemoveIncompatibleFunctions.cpp
@@ -52,11 +52,16 @@
   /// Checks a single function, returns true if the function must be deleted.
   bool checkFunction(Function &F);
 
+  /// Check and remove any incompatible attributes
+  /// that will not be supported by specific targets.
+  void removeInvalidAttributes(Function &F);
+
   bool runOnModule(Module &M) override {
     assert(TM->getTargetTriple().isAMDGCN());
 
     SmallVector<Function *, 4> FnsToDelete;
     for (Function &F : M) {
+      removeInvalidAttributes(F);
       if (checkFunction(F))
         FnsToDelete.push_back(&F);
     }
@@ -109,6 +114,37 @@
 }
 } // end anonymous namespace
 
+void AMDGPURemoveIncompatibleFunctions::removeInvalidAttributes(Function &F) {
+  if (F.isDeclaration())
+    return;
+
+  const GCNSubtarget *ST =
+      static_cast<const GCNSubtarget *>(TM->getSubtargetImpl(F));
+  bool isGfx10AndAbove = ST->getGeneration() >= AMDGPUSubtarget::GFX10;
+  Attribute FSAttr = F.getFnAttribute("target-features");
+
+  // Remove wavefrontsize32 attribute for targets below gfx10
+  if (!isGfx10AndAbove && FSAttr.isValid() &&
+      FSAttr.getValueAsString().contains("+wavefrontsize32")) {
+    std::string UpdatedFeatures;
+    SmallVector<StringRef, 8> Features;
+    FSAttr.getValueAsString().split(Features, ',');
+    for (StringRef Feature : Features) {
+      if (Feature != "+wavefrontsize32") {
+        UpdatedFeatures.append(Feature);
+        UpdatedFeatures.append(",");
+      }
+    }
+    F.removeFnAttr("target-features");
+    if (!UpdatedFeatures.empty()) {
+      // Remove last comma.
+      UpdatedFeatures.pop_back();
+      F.addFnAttr("target-features", UpdatedFeatures);
+    }
+  }
+  return;
+}
+
 bool AMDGPURemoveIncompatibleFunctions::checkFunction(Function &F) {
   if (F.isDeclaration())
     return false;


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