AMDGPU: Fix using SMRD instructions for argument loads in functions

These are not actually uniform values except in kernels.

llvm-svn: 309172

2 files changed, 31 insertions, 1 deletions

diff --git a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
index 67ad904ca97..f6d5853b2ba 100644
--- a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
@@ -730,16 +730,44 @@ bool isInlinableLiteralV216(int32_t Literal, bool HasInv2Pi) {
   return Lo16 == Hi16 && isInlinableLiteral16(Lo16, HasInv2Pi);
 }
 
+bool isArgPassedInSGPR(const Argument *A) {
+  const Function *F = A->getParent();
+
+  // Arguments to compute shaders are never a source of divergence.
+  CallingConv::ID CC = F->getCallingConv();
+  switch (CC) {
+  case CallingConv::AMDGPU_KERNEL:
+  case CallingConv::SPIR_KERNEL:
+    return true;
+  case CallingConv::AMDGPU_VS:
+  case CallingConv::AMDGPU_HS:
+  case CallingConv::AMDGPU_GS:
+  case CallingConv::AMDGPU_PS:
+  case CallingConv::AMDGPU_CS:
+    // For non-compute shaders, SGPR inputs are marked with either inreg or byval.
+    // Everything else is in VGPRs.
+    return F->getAttributes().hasParamAttribute(A->getArgNo(), Attribute::InReg) ||
+           F->getAttributes().hasParamAttribute(A->getArgNo(), Attribute::ByVal);
+  default:
+    // TODO: Should calls support inreg for SGPR inputs?
+    return false;
+  }
+}
+
+// TODO: Should largely merge with AMDGPUTTIImpl::isSourceOfDivergence.
 bool isUniformMMO(const MachineMemOperand *MMO) {
   const Value *Ptr = MMO->getValue();
   // UndefValue means this is a load of a kernel input.  These are uniform.
   // Sometimes LDS instructions have constant pointers.
   // If Ptr is null, then that means this mem operand contains a
   // PseudoSourceValue like GOT.
-  if (!Ptr || isa<UndefValue>(Ptr) || isa<Argument>(Ptr) ||
+  if (!Ptr || isa<UndefValue>(Ptr) ||
       isa<Constant>(Ptr) || isa<GlobalValue>(Ptr))
     return true;
 
+  if (const Argument *Arg = dyn_cast<Argument>(Ptr))
+    return isArgPassedInSGPR(Arg);
+
   const Instruction *I = dyn_cast<Instruction>(Ptr);
   return I && I->getMetadata("amdgpu.uniform");
 }
diff --git a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
index 936e4921a70..ea9dcdf8f3c 100644
--- a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
+++ b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
@@ -23,6 +23,7 @@
 
 namespace llvm {
 
+class Argument;
 class FeatureBitset;
 class Function;
 class GlobalValue;
@@ -347,6 +348,7 @@ bool isInlinableLiteral16(int16_t Literal, bool HasInv2Pi);
 LLVM_READNONE
 bool isInlinableLiteralV216(int32_t Literal, bool HasInv2Pi);
 
+bool isArgPassedInSGPR(const Argument *Arg);
 bool isUniformMMO(const MachineMemOperand *MMO);
 
 /// \returns The encoding that will be used for \p ByteOffset in the SMRD