[llvm] [DebugInfo][LoopDistribute] Salvage debug values using dead instructions in the distributed loops (PR #137124)

via llvm-commits llvm-commits at lists.llvm.org
Wed Apr 23 23:41:23 PDT 2025 

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Shan Huang (Apochens)

<details>
<summary>Changes</summary>

Fix #<!-- -->136532 .

---
Full diff: https://github.com/llvm/llvm-project/pull/137124.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/Scalar/LoopDistribute.cpp (+2) 
- (added) llvm/test/Transforms/LoopDistribute/salvage-dbg-values-in-distributed-loops.ll (+159) 


``````````diff
diff --git a/llvm/lib/Transforms/Scalar/LoopDistribute.cpp b/llvm/lib/Transforms/Scalar/LoopDistribute.cpp
index e10d0c0defd96..0ac1a15981770 100644
--- a/llvm/lib/Transforms/Scalar/LoopDistribute.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopDistribute.cpp
@@ -58,6 +58,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Transforms/Utils/LoopUtils.h"
 #include "llvm/Transforms/Utils/LoopVersioning.h"
 #include "llvm/Transforms/Utils/ValueMapper.h"
@@ -224,6 +225,7 @@ class InstPartition {
     // Delete the instructions backwards, as it has a reduced likelihood of
     // having to update as many def-use and use-def chains.
     for (auto *Inst : reverse(Unused)) {
+      salvageDebugInfo(*Inst);
       if (!Inst->use_empty())
         Inst->replaceAllUsesWith(PoisonValue::get(Inst->getType()));
       Inst->eraseFromParent();
diff --git a/llvm/test/Transforms/LoopDistribute/salvage-dbg-values-in-distributed-loops.ll b/llvm/test/Transforms/LoopDistribute/salvage-dbg-values-in-distributed-loops.ll
new file mode 100644
index 0000000000000..9927d796a3deb
--- /dev/null
+++ b/llvm/test/Transforms/LoopDistribute/salvage-dbg-values-in-distributed-loops.ll
@@ -0,0 +1,159 @@
+; RUN: opt -passes=loop-distribute -enable-loop-distribute -S < %s  | FileCheck %s
+
+; Check that removeUnusedInsts() salvages `dbg_value`s which use dead
+; instructions in the distributed loops.
+
+define void @f(ptr noalias %a, ptr noalias %b, ptr noalias %c, ptr noalias %d, ptr noalias %e) !dbg !5 {
+; CHECK-LABEL: define void @f(
+; CHECK-SAME: ptr noalias [[A:%.*]], ptr noalias [[B:%.*]], ptr noalias [[C:%.*]], ptr noalias [[D:%.*]], ptr noalias [[E:%.*]])
+
+; CHECK:       for.body.ldist1:
+; CHECK-NEXT:    [[IND_LDIST1:%.*]] = phi i64 [ 0, %[[ENTRY_SPLIT_LDIST1:.*]] ], [ [[ADD_LDIST1:%.*]], %for.body.ldist1 ], !dbg [[DBG28:![0-9]+]]
+
+; CHECK:           store i32
+; CHECK-NEXT:      #dbg_value(!DIArgList(ptr [[D]], i64 [[IND_LDIST1]]), [[META19:![0-9]+]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_constu, 4, DW_OP_mul, DW_OP_plus, DW_OP_stack_value), [[META37:![0-9]+]])
+; CHECK-NEXT:      #dbg_value(i32 poison, [[META20:![0-9]+]], !DIExpression(), [[META38:![0-9]+]])
+; CHECK-NEXT:      #dbg_value(!DIArgList(ptr [[E]], i64 [[IND_LDIST1]]), [[META21:![0-9]+]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_constu, 4, DW_OP_mul, DW_OP_plus, DW_OP_stack_value), [[META39:![0-9]+]])
+; CHECK-NEXT:      #dbg_value(i32 poison, [[META22:![0-9]+]], !DIExpression(), [[META40:![0-9]+]])
+; CHECK-NEXT:      #dbg_value(!DIArgList(i32 poison, i32 poison), [[META23:![0-9]+]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_mul, DW_OP_stack_value), [[META41:![0-9]+]])
+; CHECK-NEXT:      #dbg_value(!DIArgList(ptr [[C]], i64 [[IND_LDIST1]]), [[META24:![0-9]+]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_constu, 4, DW_OP_mul, DW_OP_plus, DW_OP_stack_value), [[META42:![0-9]+]])
+; CHECK-NEXT:    [[EXITCOND_LDIST1:%.*]] = icmp eq i64 [[ADD_LDIST1]], 20, !dbg [[DBG43:![0-9]+]]
+; CHECK-NEXT:      #dbg_value(i1 [[EXITCOND_LDIST1]], [[META25:![0-9]+]], !DIExpression(), [[DBG43]])
+; CHECK-NEXT:    br i1 [[EXITCOND_LDIST1]], label %[[ENTRY_SPLIT:.*]], label %for.body.ldist1, !dbg [[DBG44:![0-9]+]]
+
+; CHECK:       for.body:
+; CHECK-NEXT:    [[IND:%.*]] = phi i64 [ 0, %[[ENTRY_SPLIT:.*]] ], [ [[ADD:%.*]], %for.body ], !dbg [[DBG28]]
+; CHECK-NEXT:      #dbg_value(i64 [[IND]], [[META9:![0-9]+]], !DIExpression(), [[DBG28]])
+; CHECK-NEXT:      #dbg_value(!DIArgList(ptr [[A]], i64 [[IND]]), [[META11:![0-9]+]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_constu, 4, DW_OP_mul, DW_OP_plus, DW_OP_stack_value), [[DBG29:![0-9]+]])
+; CHECK-NEXT:      #dbg_value(i32 poison, [[META12:![0-9]+]], !DIExpression(), [[DBG30:![0-9]+]])
+; CHECK-NEXT:      #dbg_value(!DIArgList(ptr [[B]], i64 [[IND]]), [[META14:![0-9]+]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_constu, 4, DW_OP_mul, DW_OP_plus, DW_OP_stack_value), [[DBG31:![0-9]+]])
+; CHECK-NEXT:      #dbg_value(i32 poison, [[META15:![0-9]+]], !DIExpression(), [[DBG32:![0-9]+]])
+; CHECK-NEXT:      #dbg_value(!DIArgList(i32 poison, i32 poison), [[META16:![0-9]+]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_mul, DW_OP_stack_value), [[DBG33:![0-9]+]])
+; CHECK-NEXT:    [[ADD]] = add nuw nsw i64 [[IND]], 1, !dbg [[DBG34:![0-9]+]]
+; CHECK-NEXT:      #dbg_value(i64 [[ADD]], [[META17:![0-9]+]], !DIExpression(), [[DBG34]])
+; CHECK-NEXT:      #dbg_value(!DIArgList(ptr [[A]], i64 [[ADD]]), [[META18:![0-9]+]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_constu, 4, DW_OP_mul, DW_OP_plus, DW_OP_stack_value), [[DBG35:![0-9]+]])
+;
+entry:
+  br label %for.body, !dbg !27
+
+for.body:                                         ; preds = %for.body, %entry
+  %ind = phi i64 [ 0, %entry ], [ %add, %for.body ], !dbg !28
+  #dbg_value(i64 %ind, !9, !DIExpression(), !28)
+  %arrayidxA = getelementptr inbounds i32, ptr %a, i64 %ind, !dbg !29
+  #dbg_value(ptr %arrayidxA, !11, !DIExpression(), !29)
+  %loadA = load i32, ptr %arrayidxA, align 4, !dbg !30
+  #dbg_value(i32 %loadA, !12, !DIExpression(), !30)
+  %arrayidxB = getelementptr inbounds i32, ptr %b, i64 %ind, !dbg !31
+  #dbg_value(ptr %arrayidxB, !14, !DIExpression(), !31)
+  %loadB = load i32, ptr %arrayidxB, align 4, !dbg !32
+  #dbg_value(i32 %loadB, !15, !DIExpression(), !32)
+  %mulA = mul i32 %loadB, %loadA, !dbg !33
+  #dbg_value(i32 %mulA, !16, !DIExpression(), !33)
+  %add = add nuw nsw i64 %ind, 1, !dbg !34
+  #dbg_value(i64 %add, !17, !DIExpression(), !34)
+  %arrayidxA_plus_4 = getelementptr inbounds i32, ptr %a, i64 %add, !dbg !35
+  #dbg_value(ptr %arrayidxA_plus_4, !18, !DIExpression(), !35)
+  store i32 %mulA, ptr %arrayidxA_plus_4, align 4, !dbg !36
+  %arrayidxD = getelementptr inbounds i32, ptr %d, i64 %ind, !dbg !37
+  #dbg_value(ptr %arrayidxD, !19, !DIExpression(), !37)
+  %loadD = load i32, ptr %arrayidxD, align 4, !dbg !38
+  #dbg_value(i32 %loadD, !20, !DIExpression(), !38)
+  %arrayidxE = getelementptr inbounds i32, ptr %e, i64 %ind, !dbg !39
+  #dbg_value(ptr %arrayidxE, !21, !DIExpression(), !39)
+  %loadE = load i32, ptr %arrayidxE, align 4, !dbg !40
+  #dbg_value(i32 %loadE, !22, !DIExpression(), !40)
+  %mulC = mul i32 %loadD, %loadE, !dbg !41
+  #dbg_value(i32 %mulC, !23, !DIExpression(), !41)
+  %arrayidxC = getelementptr inbounds i32, ptr %c, i64 %ind, !dbg !42
+  #dbg_value(ptr %arrayidxC, !24, !DIExpression(), !42)
+  store i32 %mulC, ptr %arrayidxC, align 4, !dbg !43
+  %exitcond = icmp eq i64 %add, 20, !dbg !44
+  #dbg_value(i1 %exitcond, !25, !DIExpression(), !44)
+  br i1 %exitcond, label %for.end, label %for.body, !dbg !45
+
+for.end:                                          ; preds = %for.body
+  ret void, !dbg !46
+}
+
+!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: "/app/example.ll", directory: "/")
+!2 = !{i32 20}
+!3 = !{i32 15}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = distinct !DISubprogram(name: "f", linkageName: "f", scope: null, file: !1, line: 1, type: !6, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
+!6 = !DISubroutineType(types: !7)
+!7 = !{}
+!8 = !{!9, !11, !12, !14, !15, !16, !17, !18, !19, !20, !21, !22, !23, !24, !25}
+!9 = !DILocalVariable(name: "1", scope: !5, file: !1, line: 2, type: !10)
+!10 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned)
+!11 = !DILocalVariable(name: "2", scope: !5, file: !1, line: 3, type: !10)
+!12 = !DILocalVariable(name: "3", scope: !5, file: !1, line: 4, type: !13)
+!13 = !DIBasicType(name: "ty32", size: 32, encoding: DW_ATE_unsigned)
+!14 = !DILocalVariable(name: "4", scope: !5, file: !1, line: 5, type: !10)
+!15 = !DILocalVariable(name: "5", scope: !5, file: !1, line: 6, type: !13)
+!16 = !DILocalVariable(name: "6", scope: !5, file: !1, line: 7, type: !13)
+!17 = !DILocalVariable(name: "7", scope: !5, file: !1, line: 8, type: !10)
+!18 = !DILocalVariable(name: "8", scope: !5, file: !1, line: 9, type: !10)
+!19 = !DILocalVariable(name: "9", scope: !5, file: !1, line: 11, type: !10)
+!20 = !DILocalVariable(name: "10", scope: !5, file: !1, line: 12, type: !13)
+!21 = !DILocalVariable(name: "11", scope: !5, file: !1, line: 13, type: !10)
+!22 = !DILocalVariable(name: "12", scope: !5, file: !1, line: 14, type: !13)
+!23 = !DILocalVariable(name: "13", scope: !5, file: !1, line: 15, type: !13)
+!24 = !DILocalVariable(name: "14", scope: !5, file: !1, line: 16, type: !10)
+!25 = !DILocalVariable(name: "15", scope: !5, file: !1, line: 18, type: !26)
+!26 = !DIBasicType(name: "ty8", size: 8, encoding: DW_ATE_unsigned)
+!27 = !DILocation(line: 1, column: 1, scope: !5)
+!28 = !DILocation(line: 2, column: 1, scope: !5)
+!29 = !DILocation(line: 3, column: 1, scope: !5)
+!30 = !DILocation(line: 4, column: 1, scope: !5)
+!31 = !DILocation(line: 5, column: 1, scope: !5)
+!32 = !DILocation(line: 6, column: 1, scope: !5)
+!33 = !DILocation(line: 7, column: 1, scope: !5)
+!34 = !DILocation(line: 8, column: 1, scope: !5)
+!35 = !DILocation(line: 9, column: 1, scope: !5)
+!36 = !DILocation(line: 10, column: 1, scope: !5)
+!37 = !DILocation(line: 11, column: 1, scope: !5)
+!38 = !DILocation(line: 12, column: 1, scope: !5)
+!39 = !DILocation(line: 13, column: 1, scope: !5)
+!40 = !DILocation(line: 14, column: 1, scope: !5)
+!41 = !DILocation(line: 15, column: 1, scope: !5)
+!42 = !DILocation(line: 16, column: 1, scope: !5)
+!43 = !DILocation(line: 17, column: 1, scope: !5)
+!44 = !DILocation(line: 18, column: 1, scope: !5)
+!45 = !DILocation(line: 19, column: 1, scope: !5)
+!46 = !DILocation(line: 20, column: 1, scope: !5)
+;.
+; CHECK: [[META9]] = !DILocalVariable(name: "1",
+; CHECK: [[META11]] = !DILocalVariable(name: "2",
+; CHECK: [[META12]] = !DILocalVariable(name: "3",
+; CHECK: [[META14]] = !DILocalVariable(name: "4",
+; CHECK: [[META15]] = !DILocalVariable(name: "5",
+; CHECK: [[META16]] = !DILocalVariable(name: "6",
+; CHECK: [[META17]] = !DILocalVariable(name: "7",
+; CHECK: [[META18]] = !DILocalVariable(name: "8",
+; CHECK: [[META19]] = !DILocalVariable(name: "9",
+; CHECK: [[META20]] = !DILocalVariable(name: "10",
+; CHECK: [[META21]] = !DILocalVariable(name: "11",
+; CHECK: [[META22]] = !DILocalVariable(name: "12",
+; CHECK: [[META23]] = !DILocalVariable(name: "13",
+; CHECK: [[META24]] = !DILocalVariable(name: "14",
+; CHECK: [[META25]] = !DILocalVariable(name: "15",
+; CHECK: [[DBG28]] = !DILocation(line: 2, column: 1,
+; CHECK: [[DBG29]] = !DILocation(line: 3, column: 1,
+; CHECK: [[DBG30]] = !DILocation(line: 4, column: 1,
+; CHECK: [[DBG31]] = !DILocation(line: 5, column: 1,
+; CHECK: [[DBG33]] = !DILocation(line: 7, column: 1,
+; CHECK: [[DBG34]] = !DILocation(line: 8, column: 1,
+; CHECK: [[DBG35]] = !DILocation(line: 9, column: 1,
+; CHECK: [[META37]] = !DILocation(line: 11, column: 1,
+; CHECK: [[META39]] = !DILocation(line: 13, column: 1,
+; CHECK: [[META40]] = !DILocation(line: 14, column: 1,
+; CHECK: [[META41]] = !DILocation(line: 15, column: 1,
+; CHECK: [[META42]] = !DILocation(line: 16, column: 1,
+; CHECK: [[DBG43]] = !DILocation(line: 18, column: 1,
+; CHECK: [[DBG44]] = !DILocation(line: 19, column: 1,
+;.

``````````

</details>


https://github.com/llvm/llvm-project/pull/137124

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