Remove the folding rule
getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1) to inttoptr (i64 0 to i8*) from the VMCore constant folder. It didn't handle sign-extension properly in the case where the source integer is smaller than a pointer size. And, it relied on an assumption about sizeof(i8). The Analysis constant folder still folds these kinds of things; it has access to TargetData, so it can do them right. Add a testcase which tests that the VMCore constant folder doesn't miscompile this, and that the Analysis folder does fold it. llvm-svn: 94750
This commit is contained in:
Dan Gohman
parent
29063eac23
commit
a424b9fbd1
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@ -2021,28 +2021,6 @@ Constant *llvm::ConstantFoldGetElementPtr(LLVMContext &Context,
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ConstantExpr::getGetElementPtr(
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(Constant*)CE->getOperand(0), Idxs, NumIdx);
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}
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// Fold: getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1)
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// Into: inttoptr (i64 0 to i8*)
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// This happens with pointers to member functions in C++.
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if (CE->getOpcode() == Instruction::IntToPtr && NumIdx == 1 &&
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isa<ConstantInt>(CE->getOperand(0)) && isa<ConstantInt>(Idxs[0]) &&
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cast<PointerType>(CE->getType())->getElementType() ==
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Type::getInt8Ty(Context)) {
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Constant *Base = CE->getOperand(0);
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Constant *Offset = Idxs[0];
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// Convert the smaller integer to the larger type.
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if (Offset->getType()->getPrimitiveSizeInBits() <
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Base->getType()->getPrimitiveSizeInBits())
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Offset = ConstantExpr::getSExt(Offset, Base->getType());
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else if (Base->getType()->getPrimitiveSizeInBits() <
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Offset->getType()->getPrimitiveSizeInBits())
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Base = ConstantExpr::getZExt(Base, Offset->getType());
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Base = ConstantExpr::getAdd(Base, Offset);
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return ConstantExpr::getIntToPtr(Base, CE->getType());
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}
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}
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// Check to see if any array indices are not within the corresponding
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@ -0,0 +1,84 @@
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; RUN: opt -S -o - < %s | FileCheck --check-prefix=PLAIN %s
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; RUN: opt -S -o - -instcombine -globalopt < %s | FileCheck --check-prefix=OPT %s
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; The automatic constant folder in opt does not have targetdata access, so
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; it can't fold gep arithmetic, in general. However, the constant folder run
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; from instcombine and global opt does, and can.
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; PLAIN: @G8 = global i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1)
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; PLAIN: @G1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1)
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; PLAIN: @F8 = global i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2)
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; PLAIN: @F1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2)
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; PLAIN: @H8 = global i8* getelementptr (i8* null, i32 -1)
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; PLAIN: @H1 = global i1* getelementptr (i1* null, i32 -1)
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; PLAIN: define i8* @goo8() nounwind {
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; PLAIN: ret i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1)
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; PLAIN: }
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; PLAIN: define i1* @goo1() nounwind {
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; PLAIN: ret i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1)
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; PLAIN: }
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; PLAIN: define i8* @foo8() nounwind {
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; PLAIN: ret i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2)
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; PLAIN: }
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; PLAIN: define i1* @foo1() nounwind {
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; PLAIN: ret i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2)
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; PLAIN: }
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; PLAIN: define i8* @hoo8() nounwind {
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; PLAIN: ret i8* getelementptr (i8* null, i32 -1)
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; PLAIN: }
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; PLAIN: define i1* @hoo1() nounwind {
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; PLAIN: ret i1* getelementptr (i1* null, i32 -1)
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; PLAIN: }
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; OPT: @G8 = global i8* null
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; OPT: @G1 = global i1* null
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; OPT: @F8 = global i8* inttoptr (i64 -1 to i8*)
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; OPT: @F1 = global i1* inttoptr (i64 -1 to i1*)
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; OPT: @H8 = global i8* inttoptr (i64 -1 to i8*)
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; OPT: @H1 = global i1* inttoptr (i64 -1 to i1*)
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; OPT: define i8* @goo8() nounwind {
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; OPT: ret i8* null
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; OPT: }
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; OPT: define i1* @goo1() nounwind {
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; OPT: ret i1* null
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; OPT: }
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; OPT: define i8* @foo8() nounwind {
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; OPT: ret i8* inttoptr (i64 -1 to i8*)
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; OPT: }
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; OPT: define i1* @foo1() nounwind {
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; OPT: ret i1* inttoptr (i64 -1 to i1*)
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; OPT: }
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; OPT: define i8* @hoo8() nounwind {
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; OPT: ret i8* inttoptr (i64 -1 to i8*)
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; OPT: }
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; OPT: define i1* @hoo1() nounwind {
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; OPT: ret i1* inttoptr (i64 -1 to i1*)
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; OPT: }
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64"
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@G8 = global i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1)
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@G1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1)
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@F8 = global i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2)
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@F1 = global i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2)
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@H8 = global i8* getelementptr (i8* inttoptr (i32 0 to i8*), i32 -1)
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@H1 = global i1* getelementptr (i1* inttoptr (i32 0 to i1*), i32 -1)
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define i8* @goo8() nounwind {
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ret i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -1)
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}
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define i1* @goo1() nounwind {
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ret i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -1)
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}
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define i8* @foo8() nounwind {
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ret i8* getelementptr (i8* inttoptr (i32 1 to i8*), i32 -2)
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}
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define i1* @foo1() nounwind {
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ret i1* getelementptr (i1* inttoptr (i32 1 to i1*), i32 -2)
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}
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define i8* @hoo8() nounwind {
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ret i8* getelementptr (i8* inttoptr (i32 0 to i8*), i32 -1)
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}
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define i1* @hoo1() nounwind {
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ret i1* getelementptr (i1* inttoptr (i32 0 to i1*), i32 -1)
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}
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