diff options
| -rw-r--r-- | llvm/lib/IR/ConstantFold.cpp | 101 | ||||
| -rw-r--r-- | llvm/test/Assembler/getelementptr.ll | 10 |
2 files changed, 69 insertions, 42 deletions
diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp index 575a88894dd..c06a99c0536 100644 --- a/llvm/lib/IR/ConstantFold.cpp +++ b/llvm/lib/IR/ConstantFold.cpp @@ -2192,51 +2192,68 @@ static Constant *ConstantFoldGetElementPtrImpl(Type *PointeeTy, Constant *C, bool Unknown = !isa<ConstantInt>(Idxs[0]); for (unsigned i = 1, e = Idxs.size(); i != e; Prev = Ty, Ty = cast<CompositeType>(Ty)->getTypeAtIndex(Idxs[i]), ++i) { - if (ConstantInt *CI = dyn_cast<ConstantInt>(Idxs[i])) { - if (isa<ArrayType>(Ty) && CI->getSExtValue() > 0 && - !isIndexInRangeOfSequentialType(cast<ArrayType>(Ty), CI)) { - if (isa<SequentialType>(Prev)) { - // It's out of range, but we can factor it into the prior - // dimension. - NewIdxs.resize(Idxs.size()); - uint64_t NumElements = 0; - if (auto *ATy = dyn_cast<ArrayType>(Ty)) - NumElements = ATy->getNumElements(); - else - NumElements = cast<VectorType>(Ty)->getNumElements(); - - ConstantInt *Factor = ConstantInt::get(CI->getType(), NumElements); - NewIdxs[i] = ConstantExpr::getSRem(CI, Factor); - - Constant *PrevIdx = cast<Constant>(Idxs[i - 1]); - Constant *Div = ConstantExpr::getSDiv(CI, Factor); - - unsigned CommonExtendedWidth = - std::max(PrevIdx->getType()->getIntegerBitWidth(), - Div->getType()->getIntegerBitWidth()); - CommonExtendedWidth = std::max(CommonExtendedWidth, 64U); - - // Before adding, extend both operands to i64 to avoid - // overflow trouble. - if (!PrevIdx->getType()->isIntegerTy(CommonExtendedWidth)) - PrevIdx = ConstantExpr::getSExt( - PrevIdx, - Type::getIntNTy(Div->getContext(), CommonExtendedWidth)); - if (!Div->getType()->isIntegerTy(CommonExtendedWidth)) - Div = ConstantExpr::getSExt( - Div, Type::getIntNTy(Div->getContext(), CommonExtendedWidth)); - - NewIdxs[i - 1] = ConstantExpr::getAdd(PrevIdx, Div); - } else { - // It's out of range, but the prior dimension is a struct - // so we can't do anything about it. - Unknown = true; - } - } - } else { + auto *CI = dyn_cast<ConstantInt>(Idxs[i]); + if (!CI) { // We don't know if it's in range or not. Unknown = true; + continue; + } + if (isa<StructType>(Ty)) { + // The verify makes sure that GEPs into a struct are in range. + continue; + } + auto *STy = cast<SequentialType>(Ty); + if (isa<PointerType>(STy)) { + // We don't know if it's in range or not. + Unknown = true; + continue; + } + if (isa<VectorType>(STy)) { + // There can be awkward padding in after a non-power of two vector. + Unknown = true; + continue; + } + if (isIndexInRangeOfSequentialType(STy, CI)) + // It's in range, skip to the next index. + continue; + if (!isa<SequentialType>(Prev)) { + // It's out of range, but the prior dimension is a struct + // so we can't do anything about it. + Unknown = true; + continue; + } + if (CI->getSExtValue() < 0) { + // It's out of range and negative, don't try to factor it. + Unknown = true; + continue; } + // It's out of range, but we can factor it into the prior + // dimension. + NewIdxs.resize(Idxs.size()); + // Determine the number of elements in our sequential type. + uint64_t NumElements = STy->getArrayNumElements(); + + ConstantInt *Factor = ConstantInt::get(CI->getType(), NumElements); + NewIdxs[i] = ConstantExpr::getSRem(CI, Factor); + + Constant *PrevIdx = cast<Constant>(Idxs[i - 1]); + Constant *Div = ConstantExpr::getSDiv(CI, Factor); + + unsigned CommonExtendedWidth = + std::max(PrevIdx->getType()->getIntegerBitWidth(), + Div->getType()->getIntegerBitWidth()); + CommonExtendedWidth = std::max(CommonExtendedWidth, 64U); + + // Before adding, extend both operands to i64 to avoid + // overflow trouble. + if (!PrevIdx->getType()->isIntegerTy(CommonExtendedWidth)) + PrevIdx = ConstantExpr::getSExt( + PrevIdx, Type::getIntNTy(Div->getContext(), CommonExtendedWidth)); + if (!Div->getType()->isIntegerTy(CommonExtendedWidth)) + Div = ConstantExpr::getSExt( + Div, Type::getIntNTy(Div->getContext(), CommonExtendedWidth)); + + NewIdxs[i - 1] = ConstantExpr::getAdd(PrevIdx, Div); } // If we did any factoring, start over with the adjusted indices. diff --git a/llvm/test/Assembler/getelementptr.ll b/llvm/test/Assembler/getelementptr.ll index 0a0fddfc4dd..824848d77b5 100644 --- a/llvm/test/Assembler/getelementptr.ll +++ b/llvm/test/Assembler/getelementptr.ll @@ -46,3 +46,13 @@ define <2 x i8*> @test8(<2 x [2 x i8]*> %a) { %w = getelementptr [2 x i8], <2 x [2 x i8]*> %a, <2 x i32> <i32 0, i32 0>, <2 x i8> <i8 0, i8 1> ret <2 x i8*> %w } + +@array = internal global [16 x i32] [i32 -200, i32 -199, i32 -198, i32 -197, i32 -196, i32 -195, i32 -194, i32 -193, i32 -192, i32 -191, i32 -190, i32 -189, i32 -188, i32 -187, i32 -186, i32 -185], align 16 + +; Verify that array GEP doesn't incorrectly infer inbounds. +define i32* @test9() { +entry: + ret i32* getelementptr ([16 x i32], [16 x i32]* @array, i64 0, i64 -13) +; CHECK-LABEL: define i32* @test9( +; CHECK: ret i32* getelementptr ([16 x i32], [16 x i32]* @array, i64 0, i64 -13) +} |
