Teach constant folding that an inttoptr of a
ptrtoint can be turned into a bitcast if the
integer is at least as wide as a pointer.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54752 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 1a0e4b4..d3d0eb6 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -378,6 +378,19 @@
}
return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
case Instruction::IntToPtr:
+ // If the input is a ptrtoint, turn the pair into a ptr to ptr bitcast if
+ // the int size is >= the ptr size. This requires knowing the width of a
+ // pointer, so it can't be done in ConstantExpr::getCast.
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0])) {
+ if (TD && CE->getOpcode() == Instruction::PtrToInt &&
+ TD->getPointerSizeInBits() <=
+ CE->getType()->getPrimitiveSizeInBits()) {
+ Constant *Input = CE->getOperand(0);
+ Constant *C = FoldBitCast(Input, DestTy, *TD);
+ return C ? C : ConstantExpr::getBitCast(Input, DestTy);
+ }
+ }
+ return ConstantExpr::getCast(Opcode, Ops[0], DestTy);
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt: