[llvm] 4b2d70f - [AMDGPU] Basic implementation of isExtractSubvectorCheap

[Jay Foad via llvm-commits]

Author: Jay Foad
Date: 2022-06-10T14:43:07+01:00
New Revision: 4b2d70fa5b318b0523a592b8339382e2aaa5186d

URL: https://github.com/llvm/llvm-project/commit/4b2d70fa5b318b0523a592b8339382e2aaa5186d
DIFF: https://github.com/llvm/llvm-project/commit/4b2d70fa5b318b0523a592b8339382e2aaa5186d.diff

LOG: [AMDGPU] Basic implementation of isExtractSubvectorCheap

Add a basic implementation of isExtractSubvectorCheap that only
considers extracts at offset 0.

Differential Revision: https://reviews.llvm.org/D127385

Added: 
    

Modified: 
    llvm/lib/Target/AMDGPU/SIISelLowering.cpp
    llvm/lib/Target/AMDGPU/SIISelLowering.h

Removed: 
    


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diff  --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index 8abc1bcd90c4..12a6f4f3082b 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -1581,6 +1581,15 @@ bool SITargetLowering::shouldConvertConstantLoadToIntImm(const APInt &Imm,
   return true;
 }
 
+bool SITargetLowering::isExtractSubvectorCheap(EVT ResVT, EVT SrcVT,
+                                               unsigned Index) const {
+  if (!isOperationLegalOrCustom(ISD::EXTRACT_SUBVECTOR, ResVT))
+    return false;
+
+  // TODO: Add more cases that are cheap.
+  return Index == 0;
+}
+
 bool SITargetLowering::isTypeDesirableForOp(unsigned Op, EVT VT) const {
   if (Subtarget->has16BitInsts() && VT == MVT::i16) {
     switch (Op) {

diff  --git a/llvm/lib/Target/AMDGPU/SIISelLowering.h b/llvm/lib/Target/AMDGPU/SIISelLowering.h
index 25fe8c019916..16f944fc641c 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.h
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.h
@@ -321,6 +321,9 @@ class SITargetLowering final : public AMDGPUTargetLowering {
   bool shouldConvertConstantLoadToIntImm(const APInt &Imm,
                                         Type *Ty) const override;
 
+  bool isExtractSubvectorCheap(EVT ResVT, EVT SrcVT,
+                               unsigned Index) const override;
+
   bool isTypeDesirableForOp(unsigned Op, EVT VT) const override;
 
   bool isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const override;