reenable the piece that turns trunc(zext(x)) -> x even if zext has multiple uses,

codegen has no apparent problem with the trunc version of this, because it turns
into a simple subreg idiom

llvm-svn: 93202

1 files changed, 1 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index b5da3e615be..e018b351082 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -327,9 +327,7 @@ static bool CanEvaluateTruncated(Value *V, const Type *Ty) {
   
   // If this is an extension from the dest type, we can eliminate it, even if it
   // has multiple uses.
-  // FIXME: This is currently disabled until codegen can handle this without
-  // pessimizing code, PR5997.
-  if (0 && (isa<ZExtInst>(I) || isa<SExtInst>(I)) && 
+  if ((isa<ZExtInst>(I) || isa<SExtInst>(I)) && 
       I->getOperand(0)->getType() == Ty)
     return true;