[PATCH] D149294: Do not optimize debug locations across section boundaries

[Pierre Calixte via Phabricator via llvm-commits]

pcalixte updated this revision to Diff 518477.
pcalixte added a comment.

not change - regenerate diff based on main


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D149294/new/

https://reviews.llvm.org/D149294

Files:
  llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
  llvm/test/DebugInfo/debuglineinfo-at-section-boundary.ll


Index: llvm/test/DebugInfo/debuglineinfo-at-section-boundary.ll
===================================================================
--- /dev/null
+++ llvm/test/DebugInfo/debuglineinfo-at-section-boundary.ll
@@ -0,0 +1,45 @@
+; RUN: llc -filetype=asm -asm-verbose=0 --basic-block-sections=all < %s | FileCheck %s
+;
+; Verify that AsmPrinter does not optimize debug line directives
+; across two distinct sections. Such optimization will lead
+; to incorrect debug line number if the memory layout of those
+; sections does not strictly mirror the order in the Asm file.
+;
+;    int G;
+;    void func(int x) {
+;      if (x) G=0;
+;    }
+;
+; Reduced from the above example, the IR has been modified so that
+; the store and return instructions have the same DebugLoc; in this
+; context, we should see 2 different directives for line #4
+;
+; CHECK-COUNT-2: .loc    0 4 1
+
+define void @func(i1 %0) !dbg !8 {
+  br i1 %0, label %3, label %2
+
+2:                                                ; preds = %1
+  store i32 0, ptr null, align 4, !dbg !12
+  br label %3
+
+3:                                                ; preds = %2, %1
+  ret void, !dbg !12
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!6, !7}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 16.0.2", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/tmp", checksumkind: CSK_MD5, checksum: "fd2935e6157b382ad81da17a61f24bb1")
+!2 = !{!3}
+!3 = !DIGlobalVariableExpression(var: !4, expr: !DIExpression())
+!4 = distinct !DIGlobalVariable(name: "G", scope: !0, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true)
+!5 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!6 = !{i32 7, !"Dwarf Version", i32 5}
+!7 = !{i32 2, !"Debug Info Version", i32 3}
+!8 = distinct !DISubprogram(name: "func", scope: !1, file: !1, line: 2, type: !9, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
+!9 = !DISubroutineType(types: !10)
+!10 = !{null}
+!11 = !{}
+!12 = !DILocation(line: 4, column: 1, scope: !8)
Index: llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2039,7 +2039,10 @@
   unsigned LastAsmLine =
       Asm->OutStreamer->getContext().getCurrentDwarfLoc().getLine();
 
-  if (DL == PrevInstLoc) {
+  bool PrevInstInSameSection = (!PrevInstBB ||
+         PrevInstBB->getSectionIDNum() == MI->getParent()->getSectionIDNum());
+
+  if (DL == PrevInstLoc && PrevInstInSameSection) {
     // If we have an ongoing unspecified location, nothing to do here.
     if (!DL)
       return;


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