https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/181140
Backport 4167b285e228ee1cfff77f30eee66cbc7b4dd3db Requested by: @nikic >From 9ee4ef470e9ea16c7bc69844c23d70e841e1e199 Mon Sep 17 00:00:00 2001 From: Nikita Popov <[email protected]> Date: Thu, 12 Feb 2026 14:41:00 +0100 Subject: [PATCH] [AggressiveInstCombine] Create zext during store merge (#181125) The top extracted value can include shifted-in zero bits. In that case we should emit a zext before the new store. Fixes https://github.com/llvm/llvm-project/issues/181117. (cherry picked from commit 4167b285e228ee1cfff77f30eee66cbc7b4dd3db) --- .../AggressiveInstCombine.cpp | 2 +- .../AggressiveInstCombine/X86/store-merge.ll | 17 +++++++++++++++++ 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp index 2397133fa61ef..8440c9ce9a375 100644 --- a/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp +++ b/llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp @@ -911,7 +911,7 @@ static bool mergeConsecutivePartStores(ArrayRef<PartStore> Parts, Value *Val = First.Val; if (First.ValOffset != 0) Val = Builder.CreateLShr(Val, First.ValOffset); - Val = Builder.CreateTrunc(Val, NewTy); + Val = Builder.CreateZExtOrTrunc(Val, NewTy); StoreInst *Store = Builder.CreateAlignedStore( Val, First.Store->getPointerOperand(), First.Store->getAlign()); diff --git a/llvm/test/Transforms/AggressiveInstCombine/X86/store-merge.ll b/llvm/test/Transforms/AggressiveInstCombine/X86/store-merge.ll index 56786d0f9def0..ef7e44fcf775b 100644 --- a/llvm/test/Transforms/AggressiveInstCombine/X86/store-merge.ll +++ b/llvm/test/Transforms/AggressiveInstCombine/X86/store-merge.ll @@ -881,6 +881,23 @@ define void @test_store_same_parts_twice(i32 %x, ptr %p) { ret void } +; A case where the resulting store requires a zext. +define void @test_zext_store(i56 %arg, ptr %p) { +; CHECK-LABEL: define void @test_zext_store( +; CHECK-SAME: i56 [[ARG:%.*]], ptr [[P:%.*]]) { +; CHECK-NEXT: [[TMP1:%.*]] = zext i56 [[ARG]] to i64 +; CHECK-NEXT: store i64 [[TMP1]], ptr [[P]], align 4 +; CHECK-NEXT: ret void +; + %lo = trunc i56 %arg to i32 + store i32 %lo, ptr %p, align 4 + %shr = lshr i56 %arg, 32 + %hi = trunc i56 %shr to i32 + %p.4 = getelementptr i8, ptr %p, i64 4 + store i32 %hi, ptr %p.4, align 4 + ret void +} + !0 = !{!1} !1 = !{!1, !2} !2 = !{!2} _______________________________________________ llvm-branch-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
