constant fold ptrtoint(inttoptr) with target data when available. This allows
us to fold the entry block of PR1602 to false instead of:
br i1 icmp eq (i32 and (i32 ptrtoint (void (%struct.S*)* inttoptr (i64
1 to void (%struct.S*)*) to i32), i32 1), i32 0), label %cond_next, label
%cond_true
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41023 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 9599a90..70ce349 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -217,6 +217,23 @@
case Instruction::FCmp:
return ConstantExpr::getCompare(cast<CmpInst>(I)->getPredicate(), Ops[0],
Ops[1]);
+ case Instruction::PtrToInt:
+ // If the input is a inttoptr, eliminate the pair. 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::IntToPtr) {
+ Constant *Input = CE->getOperand(0);
+ unsigned InWidth = Input->getType()->getPrimitiveSizeInBits();
+ Constant *Mask =
+ ConstantInt::get(APInt::getLowBitsSet(InWidth,
+ TD->getPointerSizeInBits()));
+ Input = ConstantExpr::getAnd(Input, Mask);
+ // Do a zext or trunc to get to the dest size.
+ return ConstantExpr::getIntegerCast(Input, I->getType(), false);
+ }
+ }
+ // FALL THROUGH.
+ case Instruction::IntToPtr:
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt:
@@ -226,8 +243,6 @@
case Instruction::SIToFP:
case Instruction::FPToUI:
case Instruction::FPToSI:
- case Instruction::PtrToInt:
- case Instruction::IntToPtr:
case Instruction::BitCast:
return ConstantExpr::getCast(Opc, Ops[0], DestTy);
case Instruction::Select: