[llvm] [DebugInfo][LoopIdiomRecognize] Fix #82582: Wrong debug location update in processLoopStridedStore (PR #82723)

Thu Feb 22 18:06:53 PST 2024

llvmbot wrote:




@llvm/pr-subscribers-llvm-transforms

Author: Shan Huang (Apochens)

<details>
<summary>Changes</summary>

This PR fixes #82582 with PR #82608 together. This PR focuses on correcting the debug location of the `NewCall` variable in the function `processLoopStridedStore` (instead of preserving the debug location, we drop it).

In addition to the source code modification and newly added regression test, the existing regression tests `debug-line.ll` and `memset-debugify-remarks.ll` need to be modified, because the original tests assume that the newly created function call to `memset` preserves the debug location of the `StoreInst` in the loop body.

---
Full diff: https://github.com/llvm/llvm-project/pull/82723.diff


4 Files Affected:

- (modified) llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp (+1-1) 
- (modified) llvm/test/Transforms/LoopIdiom/debug-line.ll (+1-1) 
- (modified) llvm/test/Transforms/LoopIdiom/memset-debugify-remarks.ll (+2-3) 
- (added) llvm/test/Transforms/LoopIdiom/processloopstridedstore-drop-debugloc.ll (+92) 


``````````diff

diff --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index 3721564890ddb4..8ddafcbf1c223c 100644
--- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -1119,7 +1119,7 @@ bool LoopIdiomRecognize::processLoopStridedStore(
       NewCall->setMetadata(LLVMContext::MD_noalias, AATags.NoAlias);
   } 
 
-  NewCall->setDebugLoc(TheStore->getDebugLoc());
+  NewCall->dropLocation();
 
   if (MSSAU) {
     MemoryAccess *NewMemAcc = MSSAU->createMemoryAccessInBB(
diff --git a/llvm/test/Transforms/LoopIdiom/debug-line.ll b/llvm/test/Transforms/LoopIdiom/debug-line.ll
index 017d63d0c14a50..58b09fab948dab 100644
--- a/llvm/test/Transforms/LoopIdiom/debug-line.ll
+++ b/llvm/test/Transforms/LoopIdiom/debug-line.ll
@@ -9,7 +9,7 @@ define void @foo(ptr nocapture %a) nounwind ssp !dbg !0 {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    tail call void @llvm.dbg.value(metadata ptr [[A:%.*]], metadata [[META7:![0-9]+]], metadata !DIExpression()), !dbg [[DBG10:![0-9]+]]
 ; CHECK-NEXT:    tail call void @llvm.dbg.value(metadata i32 0, metadata [[META11:![0-9]+]], metadata !DIExpression()), !dbg [[DBG15:![0-9]+]]
-; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr align 8 [[A]], i8 0, i64 8000, i1 false), !dbg [[DBG16:![0-9]+]]
+; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr align 8 [[A]], i8 0, i64 8000, i1 false)
 ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
 ; CHECK:       for.body:
 ; CHECK-NEXT:    [[INDVAR:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDVAR_NEXT:%.*]], [[FOR_BODY]] ]
diff --git a/llvm/test/Transforms/LoopIdiom/memset-debugify-remarks.ll b/llvm/test/Transforms/LoopIdiom/memset-debugify-remarks.ll
index 62c56d17c3baca..35d4f98badaf89 100644
--- a/llvm/test/Transforms/LoopIdiom/memset-debugify-remarks.ll
+++ b/llvm/test/Transforms/LoopIdiom/memset-debugify-remarks.ll
@@ -15,12 +15,11 @@ target triple = "x86_64-unknown-linux-gnu"
 ;     *begin = value;
 ; }
 
-; CHECK: remark: <stdin>:4:1: Transformed loop-strided store in _Z15my_basic_memsetPcS_c function into a call to llvm.memset.p0.i64() intrinsic{{$}}
+; CHECK: remark: <unknown>:0:0: Transformed loop-strided store in _Z15my_basic_memsetPcS_c function into a call to llvm.memset.p0.i64() intrinsic{{$}}
 
 ; YAML:      --- !Passed
 ; YAML-NEXT: Pass:            loop-idiom
 ; YAML-NEXT: Name:            ProcessLoopStridedStore
-; YAML-NEXT: DebugLoc:        { File: '<stdin>', Line: 4, Column: 1 }
 ; YAML-NEXT: Function:        _Z15my_basic_memsetPcS_c
 ; YAML-NEXT: Args:
 ; YAML-NEXT:   - String:          'Transformed loop-strided store in '
@@ -43,7 +42,7 @@ define void @_Z15my_basic_memsetPcS_c(ptr %ptr, ptr %end, i8 %value) {
 ; CHECK-NEXT:    br i1 [[CMP3]], label [[FOR_END:%.*]], label [[FOR_BODY_PREHEADER:%.*]], !dbg [[DBG16:![0-9]+]]
 ; CHECK:       for.body.preheader:
 ; CHECK-NEXT:    [[TMP0:%.*]] = sub i64 [[END1]], [[PTR2]], !dbg [[DBG17:![0-9]+]]
-; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr align 1 [[PTR]], i8 [[VALUE:%.*]], i64 [[TMP0]], i1 false), !dbg [[DBG18:![0-9]+]]
+; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr align 1 [[PTR]], i8 [[VALUE:%.*]], i64 [[TMP0]], i1 false)
 ; CHECK-NEXT:    br label [[FOR_BODY:%.*]], !dbg [[DBG17]]
 ; CHECK:       for.body:
 ; CHECK-NEXT:    [[PTR_ADDR_04:%.*]] = phi ptr [ [[INCDEC_PTR:%.*]], [[FOR_BODY]] ], [ [[PTR]], [[FOR_BODY_PREHEADER]] ], !dbg [[DBG19:![0-9]+]]
diff --git a/llvm/test/Transforms/LoopIdiom/processloopstridedstore-drop-debugloc.ll b/llvm/test/Transforms/LoopIdiom/processloopstridedstore-drop-debugloc.ll
new file mode 100644
index 00000000000000..5010f97262624f
--- /dev/null
+++ b/llvm/test/Transforms/LoopIdiom/processloopstridedstore-drop-debugloc.ll
@@ -0,0 +1,92 @@
+; RUN: opt < %s -passes=loop-idiom -S | FileCheck %s
+
+; Function Attrs: noinline nounwind uwtable
+define dso_local void @fun(ptr noundef %a) #0 !dbg !10 {
+
+; CHECK-LABEL: entry:
+; CHECK-NOT: call void @llvm.memset.p0.i64{{.*}}dbg {{![0-9]+}}
+entry:
+  tail call void @llvm.dbg.value(metadata ptr %a, metadata !16, metadata !DIExpression()), !dbg !17
+  tail call void @llvm.dbg.value(metadata i32 0, metadata !18, metadata !DIExpression()), !dbg !21
+  br label %for.body, !dbg !22
+
+for.body:                                         ; preds = %entry, %for.body
+  %i.01 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  tail call void @llvm.dbg.value(metadata i32 %i.01, metadata !18, metadata !DIExpression()), !dbg !21
+  %idxprom = sext i32 %i.01 to i64, !dbg !23
+  %arrayidx = getelementptr inbounds double, ptr %a, i64 %idxprom, !dbg !23
+  store double 0.000000e+00, ptr %arrayidx, align 8, !dbg !26
+  %inc = add nsw i32 %i.01, 1, !dbg !27
+  tail call void @llvm.dbg.value(metadata i32 %inc, metadata !18, metadata !DIExpression()), !dbg !21
+  %cmp = icmp slt i32 %inc, 1000, !dbg !28
+  br i1 %cmp, label %for.body, label %for.end, !dbg !22, !llvm.loop !29
+
+for.end:                                          ; preds = %for.body
+  ret void, !dbg !32
+}
+
+; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+; Function Attrs: noinline nounwind uwtable
+define dso_local i32 @main() #0 !dbg !33 {
+entry:
+  %a = alloca [1000 x double], align 16
+  call void @llvm.dbg.declare(metadata ptr %a, metadata !36, metadata !DIExpression()), !dbg !40
+  %arraydecay = getelementptr inbounds [1000 x double], ptr %a, i64 0, i64 0, !dbg !41
+  call void @fun(ptr noundef %arraydecay), !dbg !42
+  ret i32 0, !dbg !43
+}
+
+; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
+declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+attributes #0 = { noinline nounwind uwtable "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+attributes #1 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 18.0.0git (https://github.com/llvm/llvm-project.git 7e604485e18d40be6ce6310e4a3e583ca0b7df47)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "1122.c", directory: "/home/linuxbrew/llvm-debug/LoopIdiomRecognize", checksumkind: CSK_MD5, checksum: "d9d161f9aca9398de6de8509e8cd8335")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 8, !"PIC Level", i32 2}
+!6 = !{i32 7, !"PIE Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !{i32 7, !"frame-pointer", i32 2}
+!10 = distinct !DISubprogram(name: "fun", scope: !1, file: !1, line: 1, type: !11, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !15)
+!11 = !DISubroutineType(types: !12)
+!12 = !{null, !13}
+!13 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !14, size: 64)
+!14 = !DIBasicType(name: "double", size: 64, encoding: DW_ATE_float)
+!15 = !{}
+!16 = !DILocalVariable(name: "a", arg: 1, scope: !10, file: !1, line: 1, type: !13)
+!17 = !DILocation(line: 0, scope: !10)
+!18 = !DILocalVariable(name: "i", scope: !19, file: !1, line: 2, type: !20)
+!19 = distinct !DILexicalBlock(scope: !10, file: !1, line: 2, column: 5)
+!20 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!21 = !DILocation(line: 0, scope: !19)
+!22 = !DILocation(line: 2, column: 5, scope: !19)
+!23 = !DILocation(line: 3, column: 9, scope: !24)
+!24 = distinct !DILexicalBlock(scope: !25, file: !1, line: 2, column: 36)
+!25 = distinct !DILexicalBlock(scope: !19, file: !1, line: 2, column: 5)
+!26 = !DILocation(line: 3, column: 14, scope: !24)
+!27 = !DILocation(line: 2, column: 32, scope: !25)
+!28 = !DILocation(line: 2, column: 23, scope: !25)
+!29 = distinct !{!29, !22, !30, !31}
+!30 = !DILocation(line: 4, column: 5, scope: !19)
+!31 = !{!"llvm.loop.mustprogress"}
+!32 = !DILocation(line: 5, column: 1, scope: !10)
+!33 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 7, type: !34, scopeLine: 7, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !15)
+!34 = !DISubroutineType(types: !35)
+!35 = !{!20}
+!36 = !DILocalVariable(name: "a", scope: !33, file: !1, line: 8, type: !37)
+!37 = !DICompositeType(tag: DW_TAG_array_type, baseType: !14, size: 64000, elements: !38)
+!38 = !{!39}
+!39 = !DISubrange(count: 1000)
+!40 = !DILocation(line: 8, column: 12, scope: !33)
+!41 = !DILocation(line: 9, column: 9, scope: !33)
+!42 = !DILocation(line: 9, column: 5, scope: !33)
+!43 = !DILocation(line: 10, column: 5, scope: !33)

``````````

</details>


https://github.com/llvm/llvm-project/pull/82723
