Author: Nikita Popov Date: 2020-12-23T21:03:22+01:00 New Revision: 899faa50f206073cdd8eeaaa130ffa15f850e656
URL: https://github.com/llvm/llvm-project/commit/899faa50f206073cdd8eeaaa130ffa15f850e656 DIFF: https://github.com/llvm/llvm-project/commit/899faa50f206073cdd8eeaaa130ffa15f850e656.diff LOG: [InstCombine] Check inbounds in load/store of gep null transform (PR48577) If the GEP isn't inbounds, then accessing a GEP of null location is generally not UB. While this is a minimal fix, the GEP of null handling should probably be its own fold. Added: Modified: llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp llvm/test/Transforms/InstCombine/load.ll llvm/test/Transforms/InstCombine/store.ll Removed: ################################################################################ diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp index ac617ecd4fd1..71f165abe52e 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp @@ -908,7 +908,8 @@ static bool canSimplifyNullStoreOrGEP(StoreInst &SI) { auto *Ptr = SI.getPointerOperand(); if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Ptr)) - Ptr = GEPI->getOperand(0); + if (GEPI->isInBounds()) + Ptr = GEPI->getOperand(0); return (isa<ConstantPointerNull>(Ptr) && !NullPointerIsDefined(SI.getFunction(), SI.getPointerAddressSpace())); } @@ -916,7 +917,7 @@ static bool canSimplifyNullStoreOrGEP(StoreInst &SI) { static bool canSimplifyNullLoadOrGEP(LoadInst &LI, Value *Op) { if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(Op)) { const Value *GEPI0 = GEPI->getOperand(0); - if (isa<ConstantPointerNull>(GEPI0) && + if (isa<ConstantPointerNull>(GEPI0) && GEPI->isInBounds() && !NullPointerIsDefined(LI.getFunction(), GEPI->getPointerAddressSpace())) return true; } diff --git a/llvm/test/Transforms/InstCombine/load.ll b/llvm/test/Transforms/InstCombine/load.ll index a6a2155be0b5..e4ba908599c9 100644 --- a/llvm/test/Transforms/InstCombine/load.ll +++ b/llvm/test/Transforms/InstCombine/load.ll @@ -69,8 +69,9 @@ define i32 @load_gep_null_inbounds(i64 %X) { define i32 @load_gep_null_not_inbounds(i64 %X) { ; CHECK-LABEL: @load_gep_null_not_inbounds( -; CHECK-NEXT: store i32 undef, i32* null, align 536870912 -; CHECK-NEXT: ret i32 undef +; CHECK-NEXT: [[V:%.*]] = getelementptr i32, i32* null, i64 [[X:%.*]] +; CHECK-NEXT: [[R:%.*]] = load i32, i32* [[V]], align 4 +; CHECK-NEXT: ret i32 [[R]] ; %V = getelementptr i32, i32* null, i64 %X %R = load i32, i32* %V diff --git a/llvm/test/Transforms/InstCombine/store.ll b/llvm/test/Transforms/InstCombine/store.ll index cda08f89501a..d3842f4bb469 100644 --- a/llvm/test/Transforms/InstCombine/store.ll +++ b/llvm/test/Transforms/InstCombine/store.ll @@ -37,7 +37,7 @@ define void @store_at_gep_off_null_inbounds(i64 %offset) { define void @store_at_gep_off_null_not_inbounds(i64 %offset) { ; CHECK-LABEL: @store_at_gep_off_null_not_inbounds( ; CHECK-NEXT: [[PTR:%.*]] = getelementptr i32, i32* null, i64 [[OFFSET:%.*]] -; CHECK-NEXT: store i32 undef, i32* [[PTR]], align 4 +; CHECK-NEXT: store i32 24, i32* [[PTR]], align 4 ; CHECK-NEXT: ret void ; %ptr = getelementptr i32, i32 *null, i64 %offset _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
