From 153144be40855ca1e35e1bfca082e10f553bb2e5 Mon Sep 17 00:00:00 2001 From: Michael Kruse Date: Mon, 26 Apr 2021 10:52:06 -0500 Subject: [PATCH] [SimplifyCFG] Preserve metadata when unconditionalizing branches (constant condition). When replacing a conditional branch by an unconditional one because the condition is a constant, transfer the metadata to the new branch instruction. Part of fix for llvm.org/PR50060 Reviewed By: lebedev.ri Differential Revision: https://reviews.llvm.org/D101141 --- llvm/lib/Transforms/Utils/Local.cpp | 7 +- .../SimplifyCFG/pr50060-constantfold-loopid.ll | 158 +++++++++++++++++++++ 2 files changed, 164 insertions(+), 1 deletion(-) create mode 100644 llvm/test/Transforms/SimplifyCFG/pr50060-constantfold-loopid.ll diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp index 255bb8d..b61c369 100644 --- a/llvm/lib/Transforms/Utils/Local.cpp +++ b/llvm/lib/Transforms/Utils/Local.cpp @@ -167,7 +167,12 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB, bool DeleteDeadConditions, OldDest->removePredecessor(BB); // Replace the conditional branch with an unconditional one. - Builder.CreateBr(Destination); + BranchInst *NewBI = Builder.CreateBr(Destination); + + // Transfer the metadata to the new branch instruction. + NewBI->copyMetadata(*BI, {LLVMContext::MD_loop, LLVMContext::MD_dbg, + LLVMContext::MD_annotation}); + BI->eraseFromParent(); if (DTU) DTU->applyUpdates({{DominatorTree::Delete, BB, OldDest}}); diff --git a/llvm/test/Transforms/SimplifyCFG/pr50060-constantfold-loopid.ll b/llvm/test/Transforms/SimplifyCFG/pr50060-constantfold-loopid.ll new file mode 100644 index 0000000..2f12e10 --- /dev/null +++ b/llvm/test/Transforms/SimplifyCFG/pr50060-constantfold-loopid.ll @@ -0,0 +1,158 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py +; RUN: opt -S -simplifycfg < %s | FileCheck %s +; +; The branch in the latch do.cond is conditional by a constant and the +; conditional branch replaced by an unconditional one. +; Ensure that the llvm.loop metadata is transferred to the new branch +; (In for.cond.cleanup after further simplifications). +; +; llvm.org/PR50060 +; + +@n = dso_local global i32 0, align 4 +@C = dso_local global i32 0, align 4 + +; Function Attrs: nounwind +define dso_local void @_Z6test01v() addrspace(1) #0 { +; CHECK-LABEL: @_Z6test01v( +; CHECK-NEXT: entry: +; CHECK-NEXT: [[J:%.*]] = alloca i32, align 4 +; CHECK-NEXT: [[I:%.*]] = alloca i32, align 4 +; CHECK-NEXT: br label [[DO_BODY:%.*]] +; CHECK: do.body: +; CHECK-NEXT: [[TMP0:%.*]] = load i32, i32* @C, align 4, !tbaa [[TBAA2:![0-9]+]] +; CHECK-NEXT: [[INC:%.*]] = add nsw i32 [[TMP0]], 1 +; CHECK-NEXT: [[TMP1:%.*]] = bitcast i32* [[J]] to i8* +; CHECK-NEXT: call addrspace(1) void @llvm.lifetime.start.p0i8(i64 4, i8* [[TMP1]]) #[[ATTR2:[0-9]+]] +; CHECK-NEXT: store i32 0, i32* [[J]], align 4, !tbaa [[TBAA2]] +; CHECK-NEXT: br label [[FOR_COND:%.*]] +; CHECK: for.cond: +; CHECK-NEXT: [[TMP2:%.*]] = load i32, i32* [[J]], align 4, !tbaa [[TBAA2]] +; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[TMP2]], 3 +; CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY:%.*]], label [[FOR_COND_CLEANUP:%.*]] +; CHECK: for.cond.cleanup: +; CHECK-NEXT: [[TMP3:%.*]] = bitcast i32* [[J]] to i8* +; CHECK-NEXT: call addrspace(1) void @llvm.lifetime.end.p0i8(i64 4, i8* [[TMP3]]) #[[ATTR2]] +; CHECK-NEXT: br label [[DO_BODY]], !llvm.loop [[LOOP6:![0-9]+]] +; CHECK: for.body: +; CHECK-NEXT: store i32 undef, i32* [[I]], align 4 +; CHECK-NEXT: [[TMP4:%.*]] = bitcast i32* [[I]] to i8* +; CHECK-NEXT: call addrspace(1) void @llvm.lifetime.start.p0i8(i64 4, i8* [[TMP4]]) #[[ATTR2]] +; CHECK-NEXT: store i32 0, i32* [[I]], align 4, !tbaa [[TBAA2]] +; CHECK-NEXT: br label [[FOR_COND1:%.*]] +; CHECK: for.cond1: +; CHECK-NEXT: [[TMP5:%.*]] = load i32, i32* [[I]], align 4, !tbaa [[TBAA2]] +; CHECK-NEXT: [[TMP6:%.*]] = load i32, i32* @n, align 4, !tbaa [[TBAA2]] +; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[TMP5]], [[TMP6]] +; CHECK-NEXT: br i1 [[CMP2]], label [[FOR_BODY4:%.*]], label [[FOR_COND_CLEANUP3:%.*]] +; CHECK: for.cond.cleanup3: +; CHECK-NEXT: [[TMP7:%.*]] = bitcast i32* [[I]] to i8* +; CHECK-NEXT: call addrspace(1) void @llvm.lifetime.end.p0i8(i64 4, i8* [[TMP7]]) #[[ATTR2]] +; CHECK-NEXT: [[TMP8:%.*]] = load i32, i32* [[J]], align 4, !tbaa [[TBAA2]] +; CHECK-NEXT: [[INC7:%.*]] = add nsw i32 [[TMP8]], 1 +; CHECK-NEXT: store i32 [[INC7]], i32* [[J]], align 4, !tbaa [[TBAA2]] +; CHECK-NEXT: br label [[FOR_COND]], !llvm.loop [[LOOP8:![0-9]+]] +; CHECK: for.body4: +; CHECK-NEXT: [[TMP9:%.*]] = load i32, i32* [[I]], align 4, !tbaa [[TBAA2]] +; CHECK-NEXT: store volatile i32 [[TMP9]], i32* @C, align 4, !tbaa [[TBAA2]] +; CHECK-NEXT: [[TMP10:%.*]] = load i32, i32* [[I]], align 4, !tbaa [[TBAA2]] +; CHECK-NEXT: [[INC5:%.*]] = add nsw i32 [[TMP10]], 1 +; CHECK-NEXT: store i32 [[INC5]], i32* [[I]], align 4, !tbaa [[TBAA2]] +; CHECK-NEXT: br label [[FOR_COND1]], !llvm.loop [[LOOP11:![0-9]+]] +; +entry: + %j = alloca i32, align 4 + %i = alloca i32, align 4 + br label %do.body + +do.body: ; preds = %do.cond, %entry + %0 = load i32, i32* @C, align 4, !tbaa !2 + %inc = add nsw i32 %0, 1 + %1 = bitcast i32* %j to i8* + call addrspace(1) void @llvm.lifetime.start.p0i8(i64 4, i8* %1) #2 + store i32 0, i32* %j, align 4, !tbaa !2 + br label %for.cond + +for.cond: ; preds = %for.inc6, %do.body + %2 = load i32, i32* %j, align 4, !tbaa !2 + %cmp = icmp slt i32 %2, 3 + br i1 %cmp, label %for.body, label %for.cond.cleanup + +for.cond.cleanup: ; preds = %for.cond + %3 = bitcast i32* %j to i8* + call addrspace(1) void @llvm.lifetime.end.p0i8(i64 4, i8* %3) #2 + br label %for.end8 + +for.body: ; preds = %for.cond + store i32 undef, i32* %i, align 4 + %4 = bitcast i32* %i to i8* + call addrspace(1) void @llvm.lifetime.start.p0i8(i64 4, i8* %4) #2 + store i32 0, i32* %i, align 4, !tbaa !2 + br label %for.cond1 + +for.cond1: ; preds = %for.inc, %for.body + %5 = load i32, i32* %i, align 4, !tbaa !2 + %6 = load i32, i32* @n, align 4, !tbaa !2 + %cmp2 = icmp slt i32 %5, %6 + br i1 %cmp2, label %for.body4, label %for.cond.cleanup3 + +for.cond.cleanup3: ; preds = %for.cond1 + %7 = bitcast i32* %i to i8* + call addrspace(1) void @llvm.lifetime.end.p0i8(i64 4, i8* %7) #2 + br label %for.end + +for.body4: ; preds = %for.cond1 + %8 = load i32, i32* %i, align 4, !tbaa !2 + store volatile i32 %8, i32* @C, align 4, !tbaa !2 + br label %for.inc + +for.inc: ; preds = %for.body4 + %9 = load i32, i32* %i, align 4, !tbaa !2 + %inc5 = add nsw i32 %9, 1 + store i32 %inc5, i32* %i, align 4, !tbaa !2 + br label %for.cond1, !llvm.loop !6 + +for.end: ; preds = %for.cond.cleanup3 + br label %for.inc6 + +for.inc6: ; preds = %for.end + %10 = load i32, i32* %j, align 4, !tbaa !2 + %inc7 = add nsw i32 %10, 1 + store i32 %inc7, i32* %j, align 4, !tbaa !2 + br label %for.cond, !llvm.loop !8 + +for.end8: ; preds = %for.cond.cleanup + br label %do.cond + +do.cond: ; preds = %for.end8 + br i1 true, label %do.body, label %do.end, !llvm.loop !10 + +do.end: ; preds = %do.cond + ret void +} + +; Function Attrs: argmemonly nofree nosync nounwind willreturn +declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture) addrspace(1) #1 + +; Function Attrs: argmemonly nofree nosync nounwind willreturn +declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture) addrspace(1) #1 + +attributes #0 = { nounwind "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" } +attributes #1 = { argmemonly nofree nosync nounwind willreturn } +attributes #2 = { nounwind } + +!llvm.module.flags = !{!0} +!llvm.ident = !{!1} + +!0 = !{i32 1, !"wchar_size", i32 4} +!1 = !{!"clang)"} +!2 = !{!3, !3, i64 0, i64 4} +!3 = !{!4, i64 4, !"int"} +!4 = !{!5, i64 1, !"omnipotent char"} +!5 = !{!"Simple C++ TBAA"} +!6 = distinct !{!6, !7} +!7 = !{!"llvm.loop.mustprogress"} +!8 = distinct !{!8, !7, !9} +!9 = !{!"llvm.loop.unroll.disable"} +!10 = distinct !{!10, !11} +!11 = !{!"llvm.loop.unroll.count", i32 2} -- 2.7.4