From ada8f02ccd0a19b3bfc65a5a70f6ba04ce145dad Mon Sep 17 00:00:00 2001 From: Orlando Cazalet-Hyams Date: Wed, 5 Jun 2024 11:11:46 +0100 Subject: [PATCH 1/2] [DebugInfo][SelectionDAG] Fix position of salvaged 'dangling' DBG_VALUEs `SelectionDAGBuilder::handleDebugValue` has a parameter `Order` which represents the insert-at position for the new DBG_VALUE. Prior to this patch `SelectionDAGBuilder::SDNodeOrder` is used instead of the `Order` parameter. The only code-paths where `Order != SDNodeOrder` are the two calls calls to `handleDebugValue` from `salvageUnresolvedDbgValue`. `salvageUnresolvedDbgValue` is called from `resolveOrClearDbgInfo` and `dropDanglingDebugInfo`. The former is called after SelectionDAG completes one block. Some dbg.values can't be lowered to DBG_VALUEs right away. These get recorded as 'dangling' and get salvaged later through `dropDanglingDebugInfo`, or if we've still got dangling debug info once the whole block has been emitted, through `resolveOrClearDbgInfo`. Prior to this patch, DBG_VALUEs inserted using these functions are inserted at the "current" `SDNodeOrder` rather than the intended position recorded in `DanglingDebugInfo`. Fix and add test. --- .../SelectionDAG/SelectionDAGBuilder.cpp | 5 +- llvm/test/DebugInfo/X86/sdag-order.ll | 46 +++++++++++++++++++ 2 files changed, 48 insertions(+), 3 deletions(-) create mode 100644 llvm/test/DebugInfo/X86/sdag-order.ll diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index ba76456b5836a..a0de95de1653b 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -1684,7 +1684,7 @@ bool SelectionDAGBuilder::handleDebugValue(ArrayRef Values, if (!FragmentExpr) continue; SDDbgValue *SDV = DAG.getVRegDbgValue( - Var, *FragmentExpr, RegAndSize.first, false, DbgLoc, SDNodeOrder); + Var, *FragmentExpr, RegAndSize.first, false, DbgLoc, Order); DAG.AddDbgValue(SDV, false); Offset += RegisterSize; } @@ -1699,11 +1699,10 @@ bool SelectionDAGBuilder::handleDebugValue(ArrayRef Values, } // We have created a SDDbgOperand for each Value in Values. - // Should use Order instead of SDNodeOrder? assert(!LocationOps.empty()); SDDbgValue *SDV = DAG.getDbgValueList(Var, Expr, LocationOps, Dependencies, /*IsIndirect=*/false, DbgLoc, - SDNodeOrder, IsVariadic); + Order, IsVariadic); DAG.AddDbgValue(SDV, /*isParameter=*/false); return true; } diff --git a/llvm/test/DebugInfo/X86/sdag-order.ll b/llvm/test/DebugInfo/X86/sdag-order.ll new file mode 100644 index 0000000000000..f959a80656791 --- /dev/null +++ b/llvm/test/DebugInfo/X86/sdag-order.ll @@ -0,0 +1,46 @@ +; RUN: llc %s --stop-after=finalize-isel -o - | FileCheck %s + +;; Check the DBG_VALUE which is salvaged from the dbg.value using an otherwised +;; unused value is emitted at the correct position in the function. +;; Prior (-) to patching (+), these DBG_VALUEs would sink to the bottom of the +;; function: +;; │ bb.1.if.then: +;; │- $rax = COPY %1 +;; │ DBG_VALUE 0, $noreg, !9, !DIExpression(DW_OP_plus_uconst, 4, DW_OP_stack_value) +;; │+ $rax = COPY %1 +;; │ RET 0, $rax + +; CHECK: bb.1.if.then: +; CHECK-NEXT: DBG_VALUE 0, $noreg, ![[#]], !DIExpression(DW_OP_plus_uconst, 4, DW_OP_stack_value) + +target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128" +target triple = "x86_64-unknown-linux-gnu" + +define void @badger(ptr sret(i64) %sret) !dbg !5 { +entry: + %f.i = getelementptr i8, ptr null, i64 4 + br label %if.then + +if.then: ; preds = %entry + tail call void @llvm.dbg.value(metadata ptr %f.i, metadata !9, metadata !DIExpression()), !dbg !11 + ret void +} + +declare void @llvm.dbg.value(metadata, metadata, metadata) + +!llvm.dbg.cu = !{!0} +!llvm.debugify = !{!2, !3} +!llvm.module.flags = !{!4} + +!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug) +!1 = !DIFile(filename: "test.ll", directory: "/") +!2 = !{i32 3} +!3 = !{i32 1} +!4 = !{i32 2, !"Debug Info Version", i32 3} +!5 = distinct !DISubprogram(name: "_ZNK1d1gEv", linkageName: "_ZNK1d1gEv", scope: null, file: !1, line: 1, type: !6, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8) +!6 = !DISubroutineType(types: !7) +!7 = !{} +!8 = !{!9} +!9 = !DILocalVariable(name: "1", scope: !5, file: !1, line: 1, type: !10) +!10 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned) +!11 = !DILocation(line: 5, column: 1, scope: !5) From b3478704b4d7278b95da897f9989519049d89b60 Mon Sep 17 00:00:00 2001 From: Orlando Cazalet-Hyams Date: Wed, 5 Jun 2024 11:56:38 +0100 Subject: [PATCH 2/2] format --- llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index a0de95de1653b..efeaeb6ceab01 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -1700,9 +1700,9 @@ bool SelectionDAGBuilder::handleDebugValue(ArrayRef Values, // We have created a SDDbgOperand for each Value in Values. assert(!LocationOps.empty()); - SDDbgValue *SDV = DAG.getDbgValueList(Var, Expr, LocationOps, Dependencies, - /*IsIndirect=*/false, DbgLoc, - Order, IsVariadic); + SDDbgValue *SDV = + DAG.getDbgValueList(Var, Expr, LocationOps, Dependencies, + /*IsIndirect=*/false, DbgLoc, Order, IsVariadic); DAG.AddDbgValue(SDV, /*isParameter=*/false); return true; }