[PATCH] R600: Implement isTruncateFree

[Matt Arsenault]

Truncation is just accessing a subregister for any multiple of the register size, so it's free.


http://llvm-reviews.chandlerc.com/D2725

Files:
  lib/Target/R600/AMDGPUISelLowering.cpp
  lib/Target/R600/AMDGPUISelLowering.h

Index: lib/Target/R600/AMDGPUISelLowering.cpp
===================================================================
--- lib/Target/R600/AMDGPUISelLowering.cpp
+++ lib/Target/R600/AMDGPUISelLowering.cpp
@@ -234,6 +234,11 @@
   return VT == MVT::f32;
 }
 
+bool AMDGPUTargetLowering::isTruncateFree(EVT, EVT Dest) const {
+  // Truncate is just access a subregister.
+  return (Dest.getSizeInBits() % 32 == 0);
+}
+
 //===---------------------------------------------------------------------===//
 // TargetLowering Callbacks
 //===---------------------------------------------------------------------===//
Index: lib/Target/R600/AMDGPUISelLowering.h
===================================================================
--- lib/Target/R600/AMDGPUISelLowering.h
+++ lib/Target/R600/AMDGPUISelLowering.h
@@ -85,6 +85,7 @@
 
   virtual bool isFAbsFree(EVT VT) const;
   virtual bool isFNegFree(EVT VT) const;
+  virtual bool isTruncateFree(EVT Src, EVT Dest) const LLVM_OVERRIDE;
   virtual MVT getVectorIdxTy() const;
   virtual bool isLoadBitCastBeneficial(EVT, EVT) const LLVM_OVERRIDE;
   virtual SDValue LowerReturn(SDValue Chain, CallingConv::ID CallConv,
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D2725.1.patch
Type: text/x-patch
Size: 1154 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20140207/4386b135/attachment.bin>