[llvm] r204739 - [X86TTI] Make constant base pointers for getElementPtr opaque.

[Juergen Ributzka]

Author: ributzka
Date: Tue Mar 25 13:01:25 2014
New Revision: 204739

URL: http://llvm.org/viewvc/llvm-project?rev=204739&view=rev
Log:
[X86TTI] Make constant base pointers for getElementPtr opaque.

If getElementPtr uses a constant as base pointer, then make the constant opaque.
This prevents constant folding it with the offset. The offset can usually be
encoded in the load/store instruction itself and the base address doesn't have
to be rematerialized several times.

Modified:
    llvm/trunk/lib/Target/X86/X86TargetTransformInfo.cpp

Modified: llvm/trunk/lib/Target/X86/X86TargetTransformInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86TargetTransformInfo.cpp?rev=204739&r1=204738&r2=204739&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86TargetTransformInfo.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86TargetTransformInfo.cpp Tue Mar 25 13:01:25 2014
@@ -798,8 +798,9 @@ unsigned X86TTI::getIntImmCost(unsigned
   switch (Opcode) {
   default: return TCC_Free;
   case Instruction::GetElementPtr:
-    if (Idx != 0)
-      return TCC_Free;
+    if (Idx == 0)
+      return 2 * TCC_Basic;
+    return TCC_Free;
   case Instruction::Store:
     ImmIdx = 0;
     break;