https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/150646
Backport 2d0ca09305fcece75e2c501f1ec74aa6eada69a0 Requested by: @dtcxzyw >From 15fbe94cc3389b0fa8c820d06d83c42333b53631 Mon Sep 17 00:00:00 2001 From: Yingwei Zheng <dtcxzyw2...@gmail.com> Date: Sat, 26 Jul 2025 00:23:56 +0800 Subject: [PATCH] [CodeGenPrepare] Make sure that `AddOffset` is also a loop invariant (#150625) Closes https://github.com/llvm/llvm-project/issues/150611. (cherry picked from commit 2d0ca09305fcece75e2c501f1ec74aa6eada69a0) --- llvm/lib/CodeGen/CodeGenPrepare.cpp | 4 +++ .../CodeGenPrepare/X86/fold-loop-of-urem.ll | 34 +++++++++++++++++++ 2 files changed, 38 insertions(+) diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp index 9bbb89e37865d..3d1408256df8e 100644 --- a/llvm/lib/CodeGen/CodeGenPrepare.cpp +++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp @@ -2096,6 +2096,10 @@ static bool isRemOfLoopIncrementWithLoopInvariant( if (!L->isLoopInvariant(RemAmt)) return false; + // Only works if the AddOffset is a loop invaraint + if (AddOffset && !L->isLoopInvariant(AddOffset)) + return false; + // Is the PHI a loop increment? auto LoopIncrInfo = getIVIncrement(PN, LI); if (!LoopIncrInfo) diff --git a/llvm/test/Transforms/CodeGenPrepare/X86/fold-loop-of-urem.ll b/llvm/test/Transforms/CodeGenPrepare/X86/fold-loop-of-urem.ll index 7abc32e4f1cd8..f53127f015391 100644 --- a/llvm/test/Transforms/CodeGenPrepare/X86/fold-loop-of-urem.ll +++ b/llvm/test/Transforms/CodeGenPrepare/X86/fold-loop-of-urem.ll @@ -1065,3 +1065,37 @@ for.body: %exitcond.not = icmp eq i32 %inc, %N br i1 %exitcond.not, label %for.cond.cleanup, label %for.body } + +define i64 @pr150611_add_offset_is_not_loop_invariant(i1 %cond) { +; CHECK-LABEL: define i64 @pr150611_add_offset_is_not_loop_invariant( +; CHECK-SAME: i1 [[COND:%.*]]) { +; CHECK-NEXT: [[ENTRY:.*]]: +; CHECK-NEXT: [[REMAMT:%.*]] = select i1 [[COND]], i64 2, i64 0 +; CHECK-NEXT: br label %[[FOR_BODY:.*]] +; CHECK: [[FOR_BODY]]: +; CHECK-NEXT: [[INDVARS:%.*]] = phi i64 [ 0, %[[ENTRY]] ], [ [[INDVARS_NEXT:%.*]], %[[FOR_BODY]] ] +; CHECK-NEXT: [[ADD_OFFSET:%.*]] = zext i1 [[COND]] to i64 +; CHECK-NEXT: [[ADD:%.*]] = add nuw i64 [[INDVARS]], [[ADD_OFFSET]] +; CHECK-NEXT: [[REM:%.*]] = urem i64 [[ADD]], [[REMAMT]] +; CHECK-NEXT: [[INDVARS_NEXT]] = add nuw i64 [[INDVARS]], 1 +; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[INDVARS_NEXT]], 3 +; CHECK-NEXT: br i1 [[EXITCOND]], label %[[FOR_EXIT:.*]], label %[[FOR_BODY]] +; CHECK: [[FOR_EXIT]]: +; CHECK-NEXT: ret i64 [[REM]] +; +entry: + %remamt = select i1 %cond, i64 2, i64 0 + br label %for.body + +for.body: + %indvars = phi i64 [ 0, %entry ], [ %indvars.next, %for.body ] + %add.offset = zext i1 %cond to i64 + %add = add nuw i64 %indvars, %add.offset + %rem = urem i64 %add, %remamt + %indvars.next = add nuw i64 %indvars, 1 + %exitcond = icmp eq i64 %indvars.next, 3 + br i1 %exitcond, label %for.exit, label %for.body + +for.exit: + ret i64 %rem +} _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
