Changes in directory llvm/lib/VMCore:
ConstantFolding.cpp updated: 1.111 -> 1.112
---
Log message:
Implement correct constant folding of bitcast. This implements
Transforms/ConstProp/bitcast.ll and fixes
SingleSource/Regression/C/2003-10-12-GlobalVarInitializers
---
Diffs of the changes: (+33 -15)
ConstantFolding.cpp | 48 +++++++++++++++++++++++++++++++++---------------
1 files changed, 33 insertions(+), 15 deletions(-)
Index: llvm/lib/VMCore/ConstantFolding.cpp
diff -u llvm/lib/VMCore/ConstantFolding.cpp:1.111
llvm/lib/VMCore/ConstantFolding.cpp:1.112
--- llvm/lib/VMCore/ConstantFolding.cpp:1.111 Sun Dec 10 20:16:58 2006
+++ llvm/lib/VMCore/ConstantFolding.cpp Mon Dec 11 12:30:27 2006
@@ -828,10 +828,6 @@
const Type *DestTy) {
const Type *SrcTy = V->getType();
- // Handle some simple cases
- if (SrcTy == DestTy)
- return (Constant*)V; // no-op cast
-
if (isa<UndefValue>(V))
return UndefValue::get(DestTy);
@@ -901,6 +897,8 @@
return ConstantIntegral::get(DestTy, CI->getZExtValue());
return 0;
case Instruction::BitCast:
+ if (SrcTy == DestTy) return (Constant*)V; // no-op cast
+
// Check to see if we are casting a pointer to an aggregate to a pointer to
// the first element. If so, return the appropriate GEP instruction.
if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
@@ -960,18 +958,38 @@
}
}
- // Handle sign conversion for integer no-op casts. We need to cast the
- // value to the correct signedness before we try to cast it to the
- // destination type. Be careful to do this only for integer types.
- if (isa<ConstantIntegral>(V) && SrcTy->isInteger()) {
- if (SrcTy->isSigned())
- V = ConstantInt::get(SrcTy->getUnsignedVersion(),
- cast<ConstantIntegral>(V)->getZExtValue());
- else
- V = ConstantInt::get(SrcTy->getSignedVersion(),
- cast<ConstantIntegral>(V)->getSExtValue());
+ // Finally, implement bitcast folding now. The code below doesn't handle
+ // bitcast right.
+ if (isa<ConstantPointerNull>(V)) // ptr->ptr cast.
+ return ConstantPointerNull::get(cast<PointerType>(DestTy));
+
+ // Handle integral constant input.
+ if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
+ // Integral -> Integral, must be changing sign.
+ if (DestTy->isIntegral())
+ return ConstantInt::get(DestTy, CI->getZExtValue());
+
+ if (DestTy->isFloatingPoint()) {
+ if (DestTy == Type::FloatTy)
+ return ConstantFP::get(DestTy, BitsToFloat(CI->getZExtValue()));
+ assert(DestTy == Type::DoubleTy && "Unknown FP type!");
+ return ConstantFP::get(DestTy, BitsToDouble(CI->getZExtValue()));
+ }
+ // Otherwise, can't fold this (packed?)
+ return 0;
}
- break;
+
+ // Handle ConstantFP input.
+ if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
+ // FP -> Integral.
+ if (DestTy->isIntegral()) {
+ if (DestTy == Type::FloatTy)
+ return ConstantInt::get(DestTy, FloatToBits(FP->getValue()));
+ assert(DestTy == Type::DoubleTy && "Unknown FP type!");
+ return ConstantInt::get(DestTy, DoubleToBits(FP->getValue()));
+ }
+ }
+ return 0;
default:
assert(!"Invalid CE CastInst opcode");
break;
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