diff options
| -rw-r--r-- | llvm/lib/Transforms/Scalar/GVNHoist.cpp | 16 | ||||
| -rw-r--r-- | llvm/test/Transforms/GVN/hoist-pr28933.ll | 21 |
2 files changed, 32 insertions, 5 deletions
diff --git a/llvm/lib/Transforms/Scalar/GVNHoist.cpp b/llvm/lib/Transforms/Scalar/GVNHoist.cpp index 63f00256248..0d7364bb974 100644 --- a/llvm/lib/Transforms/Scalar/GVNHoist.cpp +++ b/llvm/lib/Transforms/Scalar/GVNHoist.cpp @@ -740,10 +740,14 @@ private: if (!Repl || firstInBB(I, Repl)) Repl = I; + // Keep track of whether we moved the instruction so we know whether we + // should move the MemoryAccess. + bool MoveAccess = true; if (Repl) { // Repl is already in HoistPt: it remains in place. assert(allOperandsAvailable(Repl, HoistPt) && "instruction depends on operands that are not available"); + MoveAccess = false; } else { // When we do not find Repl in HoistPt, select the first in the list // and move it to HoistPt. @@ -771,14 +775,16 @@ private: DFSNumber[Repl] = DFSNumber[Last]++; } - MemoryAccess *NewMemAcc = nullptr; - if (MemoryAccess *MA = MSSA->getMemoryAccess(Repl)) { - if (MemoryUseOrDef *OldMemAcc = dyn_cast<MemoryUseOrDef>(MA)) { + MemoryAccess *NewMemAcc = MSSA->getMemoryAccess(Repl); + + if (MoveAccess) { + if (MemoryUseOrDef *OldMemAcc = + dyn_cast_or_null<MemoryUseOrDef>(NewMemAcc)) { // The definition of this ld/st will not change: ld/st hoisting is // legal when the ld/st is not moved past its current definition. MemoryAccess *Def = OldMemAcc->getDefiningAccess(); - NewMemAcc = MSSA->createMemoryAccessInBB(Repl, Def, HoistPt, - MemorySSA::End); + NewMemAcc = + MSSA->createMemoryAccessInBB(Repl, Def, HoistPt, MemorySSA::End); OldMemAcc->replaceAllUsesWith(NewMemAcc); MSSA->removeMemoryAccess(OldMemAcc); } diff --git a/llvm/test/Transforms/GVN/hoist-pr28933.ll b/llvm/test/Transforms/GVN/hoist-pr28933.ll new file mode 100644 index 00000000000..95df3f220f2 --- /dev/null +++ b/llvm/test/Transforms/GVN/hoist-pr28933.ll @@ -0,0 +1,21 @@ +; RUN: opt -S -gvn-hoist -verify-memoryssa < %s | FileCheck %s + +; Check that we end up with one load and one store, in the right order +; CHECK-LABEL: define void @test_it( +; CHECK: store +; CHECK-NEXT: load +; CHECK-NOT: store +; CHECK-NOT: load + +%rec894.0.1.2.3.12 = type { i16 } + +@a = external global %rec894.0.1.2.3.12 + +define void @test_it() { +bb2: + store i16 undef, i16* getelementptr inbounds (%rec894.0.1.2.3.12, %rec894.0.1.2.3.12* @a, i16 0, i32 0), align 1 + %_tmp61 = load i16, i16* getelementptr inbounds (%rec894.0.1.2.3.12, %rec894.0.1.2.3.12* @a, i16 0, i32 0), align 1 + store i16 undef, i16* getelementptr inbounds (%rec894.0.1.2.3.12, %rec894.0.1.2.3.12* @a, i16 0, i32 0), align 1 + %_tmp92 = load i16, i16* getelementptr inbounds (%rec894.0.1.2.3.12, %rec894.0.1.2.3.12* @a, i16 0, i32 0), align 1 + ret void +} |
