[DebugInfo] Fix #76058: missing debug location in processSDiv function

[Apochens]

This PR fixes #76058

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[llvmbot]

@llvm/pr-subscribers-debuginfo

@llvm/pr-subscribers-llvm-transforms

Author: Shan Huang (Apochens)

Changes

This PR fixes #76058

---

Full diff: https://github.com/llvm/llvm-project/pull/76118.diff

2 Files Affected:

• (modified) llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp (+4-2)
• (added) llvm/test/Transforms/CorrelatedValuePropagation/sdiv_missing_debugloc.ll (+50)

diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index d2dfc764d042bb..c44d3748a80d8b 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -935,11 +935,13 @@ static bool processSDiv(BinaryOperator *SDI, const ConstantRange &LCR,
   UDiv->setDebugLoc(SDI->getDebugLoc());
   UDiv->setIsExact(SDI->isExact());
 
-  Value *Res = UDiv;
+  auto *Res = UDiv;
 
   // If the operands had two different domains, we need to negate the result.
-  if (Ops[0].D != Ops[1].D)
+  if (Ops[0].D != Ops[1].D) {
     Res = BinaryOperator::CreateNeg(Res, Res->getName() + ".neg", SDI);
+    Res->setDebugLoc(SDI->getDebugLoc());
+  }
 
   SDI->replaceAllUsesWith(Res);
   SDI->eraseFromParent();
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/sdiv_missing_debugloc.ll b/llvm/test/Transforms/CorrelatedValuePropagation/sdiv_missing_debugloc.ll
new file mode 100644
index 00000000000000..523f58f9872882
--- /dev/null
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/sdiv_missing_debugloc.ll
@@ -0,0 +1,50 @@
+; RUN: opt -passes=correlated-propagation -S < %s | FileCheck %s
+; CHECK: %{{[a-zA-Z0-9_]*}} = udiv i8 %x.nonneg, %y, !dbg ![[DBGLOC:[0-9]+]]
+; CHECK-NEXT: %{{[a-zA-Z0-9_]*}}.neg = sub i8 0, %rem1, !dbg ![[DBGLOC]]
+
+; ModuleID = 'reduced.ll'
+source_filename = "orig.ll"
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv7m-arm-none-eabi"
+
+; Function Attrs: inaccessiblememonly nocallback nofree nosync nounwind willreturn
+declare void @llvm.assume(i1 noundef) #0
+
+define void @test8_neg_neg(i8 %x, i8 %y) !dbg !5 {
+  %c0 = icmp sle i8 %x, 0, !dbg !13
+  call void @llvm.dbg.value(metadata i1 %c0, metadata !9, metadata !DIExpression()), !dbg !13
+  call void @llvm.assume(i1 %c0), !dbg !14
+  %c1 = icmp sge i8 %y, 0, !dbg !15
+  call void @llvm.dbg.value(metadata i1 %c1, metadata !11, metadata !DIExpression()), !dbg !15
+  call void @llvm.assume(i1 %c1), !dbg !16
+  %rem = sdiv i8 %x, %y, !dbg !17
+  call void @llvm.dbg.value(metadata i8 %rem, metadata !12, metadata !DIExpression()), !dbg !17
+  ret void, !dbg !18
+}
+
+; Function Attrs: nocallback nofree nosync nounwind readnone speculatable willreturn
+declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+!llvm.module.flags = !{!0}
+!llvm.dbg.cu = !{!1}
+!llvm.debugify = !{!3, !4}
+
+!0 = !{i32 2, !"Debug Info Version", i32 3}
+!1 = distinct !DICompileUnit(language: DW_LANG_C, file: !2, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
+!2 = !DIFile(filename: "reduced.ll", directory: "/")
+!3 = !{i32 6}
+!4 = !{i32 3}
+!5 = distinct !DISubprogram(name: "test8_neg_neg", linkageName: "test8_neg_neg", scope: null, file: !2, line: 1, type: !6, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !1, retainedNodes: !8)
+!6 = !DISubroutineType(types: !7)
+!7 = !{}
+!8 = !{!9, !11, !12}
+!9 = !DILocalVariable(name: "1", scope: !5, file: !2, line: 1, type: !10)
+!10 = !DIBasicType(name: "ty8", size: 8, encoding: DW_ATE_unsigned)
+!11 = !DILocalVariable(name: "2", scope: !5, file: !2, line: 3, type: !10)
+!12 = !DILocalVariable(name: "3", scope: !5, file: !2, line: 5, type: !10)
+!13 = !DILocation(line: 1, column: 1, scope: !5)
+!14 = !DILocation(line: 2, column: 1, scope: !5)
+!15 = !DILocation(line: 3, column: 1, scope: !5)
+!16 = !DILocation(line: 4, column: 1, scope: !5)
+!17 = !DILocation(line: 5, column: 1, scope: !5)
+!18 = !DILocation(line: 6, column: 1, scope: !5)
\ No newline at end of file

[nikic]

Looks fine, some test nits.

[nikic]

Please move these check lines lower (e.g. directly above the function).

[Apochens]

Hi, Nikita! To refine the testcase, I (1) removed line 5-8, moving the check lines directly above the function, and (2) discarded the llvm.debugify metadata (since it's not necessary). After the refinement, I tested the patch on this testcase, and It does work.

Could you please review this PR again to check whether there is any other issue? Thanks.