AMDGPU: Implement isCheapAddrSpaceCast

llvm-svn: 288523

1 files changed, 12 insertions, 2 deletions

diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index ac5fddfd42d..ef61fc409f8 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -600,8 +600,8 @@ EVT SITargetLowering::getOptimalMemOpType(uint64_t Size, unsigned DstAlign,
 
 static bool isFlatGlobalAddrSpace(unsigned AS) {
   return AS == AMDGPUAS::GLOBAL_ADDRESS ||
-    AS == AMDGPUAS::FLAT_ADDRESS ||
-    AS == AMDGPUAS::CONSTANT_ADDRESS;
+         AS == AMDGPUAS::FLAT_ADDRESS ||
+         AS == AMDGPUAS::CONSTANT_ADDRESS;
 }
 
 bool SITargetLowering::isNoopAddrSpaceCast(unsigned SrcAS,
@@ -609,6 +609,16 @@ bool SITargetLowering::isNoopAddrSpaceCast(unsigned SrcAS,
   return isFlatGlobalAddrSpace(SrcAS) && isFlatGlobalAddrSpace(DestAS);
 }
 
+bool SITargetLowering::isCheapAddrSpaceCast(unsigned SrcAS,
+                                            unsigned DestAS) const {
+  // Flat -> private/local is a simple truncate.
+  // Flat -> global is no-op
+  if (SrcAS == AMDGPUAS::FLAT_ADDRESS)
+    return true;
+
+  return isNoopAddrSpaceCast(SrcAS, DestAS);
+}
+
 bool SITargetLowering::isMemOpUniform(const SDNode *N) const {
   const MemSDNode *MemNode = cast<MemSDNode>(N);
   const Value *Ptr = MemNode->getMemOperand()->getValue();