Revert remaining part of r93200: "Disable folding sext(trunc(x)) -> x"
This fixes PR5997.
These transforms were disabled because codegen couldn't deal with other
uses of trunc(x). This is now handled by the peephole pass.
This causes no regressions on x86-64.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159003 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp
index fa24800..555b442 100644
--- a/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -648,10 +648,8 @@
if (!I) return false;
// If the input is a truncate from the destination type, we can trivially
- // 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<TruncInst>(I) && I->getOperand(0)->getType() == Ty)
+ // eliminate it.
+ if (isa<TruncInst>(I) && I->getOperand(0)->getType() == Ty)
return true;
// We can't extend or shrink something that has multiple uses: doing so would
@@ -992,11 +990,8 @@
Instruction *I = dyn_cast<Instruction>(V);
if (!I) return false;
- // If this is a truncate from the dest type, we can trivially 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<TruncInst>(I) && I->getOperand(0)->getType() == Ty)
+ // If this is a truncate from the dest type, we can trivially eliminate it.
+ if (isa<TruncInst>(I) && I->getOperand(0)->getType() == Ty)
return true;
// We can't extend or shrink something that has multiple uses: doing so would