From 861c9a7f2593867e02dd85eb24c31ec7c07e3802 Mon Sep 17 00:00:00 2001 From: Florian Hahn Date: Thu, 25 Sep 2025 13:22:59 +0100 Subject: [PATCH 1/2] [InstCombine] Remove redundant align 1 assumptions. It seems like we have a bunch of align 1 assumptions in practice and unless I am missing something they should not add any value. See https://github.com/dtcxzyw/llvm-opt-benchmark/pull/2861/files --- llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp index 6ad493772d170..04f787aae11aa 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -3412,6 +3412,10 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) { !isPowerOf2_64(RK.ArgValue) || !isa(RK.IRArgValue)) continue; + // Remove align 1 bundles; they don't add any useful information. + if (RK.ArgValue == 1) + return CallBase::removeOperandBundle(II, OBU.getTagID()); + // Don't try to remove align assumptions for pointers derived from // arguments. We might lose information if the function gets inline and // the align argument attribute disappears. From f2126d5c8020564657fdc5a24445ae4748dfe113 Mon Sep 17 00:00:00 2001 From: Florian Hahn Date: Thu, 25 Sep 2025 13:54:25 +0100 Subject: [PATCH 2/2] !fixup update test --- llvm/test/Transforms/InstCombine/assume-align.ll | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/llvm/test/Transforms/InstCombine/assume-align.ll b/llvm/test/Transforms/InstCombine/assume-align.ll index f6373d85ddb9c..4185b10eeca95 100644 --- a/llvm/test/Transforms/InstCombine/assume-align.ll +++ b/llvm/test/Transforms/InstCombine/assume-align.ll @@ -249,8 +249,7 @@ define ptr @redundant_assume_align_8_via_asume(ptr %p) { define ptr @assume_align_1(ptr %p) { ; CHECK-LABEL: @assume_align_1( -; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[P:%.*]], i32 1) ] -; CHECK-NEXT: call void @foo(ptr [[P]]) +; CHECK-NEXT: call void @foo(ptr [[P:%.*]]) ; CHECK-NEXT: ret ptr [[P]] ; call void @llvm.assume(i1 true) [ "align"(ptr %p, i32 1) ]