From f241fec5ea96b5fafa963beac3d7934da1db9f74 Mon Sep 17 00:00:00 2001 From: Vedant Kumar Date: Tue, 17 Jul 2018 18:08:36 +0000 Subject: [PATCH] [InstCombine] Preserve debug value when simplifying cast-of-select InstCombine has a cast transform that matches a cast-of-select: Orig = cast (Src = select Cond TV FV) And tries to replace it with a select which has the cast folded in: NewSel = select Cond (cast TV) (cast FV) The combiner does RAUW(Orig, NewSel), so any debug values for Orig would survive the transform. But debug values for Src would be lost. This patch teaches InstCombine to replace all debug uses of Src with NewSel (taking care of doing any necessary DIExpression rewriting). Differential Revision: https://reviews.llvm.org/D49270 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@337310 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/InstCombine/InstCombineCasts.cpp | 4 +++- test/Transforms/InstCombine/debuginfo-variables.ll | 11 +++++++++++ 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp index 481e40612c3..e8ea7396a96 100644 --- a/lib/Transforms/InstCombine/InstCombineCasts.cpp +++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp @@ -282,8 +282,10 @@ Instruction *InstCombiner::commonCastTransforms(CastInst &CI) { // condition may inhibit other folds and lead to worse codegen. auto *Cmp = dyn_cast(Sel->getCondition()); if (!Cmp || Cmp->getOperand(0)->getType() != Sel->getType()) - if (Instruction *NV = FoldOpIntoSelect(CI, Sel)) + if (Instruction *NV = FoldOpIntoSelect(CI, Sel)) { + replaceAllDbgUsesWith(*Sel, *NV, CI, DT); return NV; + } } // If we are casting a PHI, then fold the cast into the PHI. diff --git a/test/Transforms/InstCombine/debuginfo-variables.ll b/test/Transforms/InstCombine/debuginfo-variables.ll index d277b6c3233..dcb07d5e678 100644 --- a/test/Transforms/InstCombine/debuginfo-variables.ll +++ b/test/Transforms/InstCombine/debuginfo-variables.ll @@ -26,6 +26,17 @@ define i64 @test_used_sext_zext(i16 %A) { ret i64 %c2 } +define i32 @test_cast_select(i1 %cond) { +; CHECK-LABEL: @test_cast_select( +; CHECK-NEXT: [[sel:%.*]] = select i1 %cond, i32 3, i32 5 +; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 [[sel]], {{.*}}, metadata !DIExpression()) +; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 [[sel]], {{.*}}, metadata !DIExpression()) +; CHECK-NEXT: ret i32 [[sel]] + %sel = select i1 %cond, i16 3, i16 5 + %cast = zext i16 %sel to i32 + ret i32 %cast +} + define void @test_or(i64 %A) { ; CHECK-LABEL: @test_or( ; CHECK-NEXT: call void @llvm.dbg.value(metadata i64 %A, {{.*}}, metadata !DIExpression(DW_OP_constu, 256, DW_OP_or, DW_OP_stack_value)) -- 2.50.1