[llvm] 041ac7a - [DWARF] Don't leak line numbers onto frame-setup instructions (#161845)
via llvm-commits
llvm-commits at lists.llvm.org
Fri Oct 17 07:25:00 PDT 2025
Author: Orlando Cazalet-Hyams
Date: 2025-10-17T15:24:56+01:00
New Revision: 041ac7a193e0da962f2f9822fb4a7a720b36105a
URL: https://github.com/llvm/llvm-project/commit/041ac7a193e0da962f2f9822fb4a7a720b36105a
DIFF: https://github.com/llvm/llvm-project/commit/041ac7a193e0da962f2f9822fb4a7a720b36105a.diff
LOG: [DWARF] Don't leak line numbers onto frame-setup instructions (#161845)
Fixes issue #157887
Added:
llvm/test/DebugInfo/X86/shrink-wrap-frame-setup-no-loc.mir
Modified:
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 433877f3a8b98..72582d7324629 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2066,11 +2066,36 @@ void DwarfDebug::beginInstruction(const MachineInstr *MI) {
if (NoDebug)
return;
+ auto RecordLineZero = [&]() {
+ // Preserve the file and column numbers, if we can, to save space in
+ // the encoded line table.
+ // Do not update PrevInstLoc, it remembers the last non-0 line.
+ const MDNode *Scope = nullptr;
+ unsigned Column = 0;
+ if (PrevInstLoc) {
+ Scope = PrevInstLoc.getScope();
+ Column = PrevInstLoc.getCol();
+ }
+ recordSourceLine(/*Line=*/0, Column, Scope, /*Flags=*/0);
+ };
+
+ // When we emit a line-0 record, we don't update PrevInstLoc; so look at
+ // the last line number actually emitted, to see if it was line 0.
+ unsigned LastAsmLine =
+ Asm->OutStreamer->getContext().getCurrentDwarfLoc().getLine();
+
// Check if source location changes, but ignore DBG_VALUE and CFI locations.
// If the instruction is part of the function frame setup code, do not emit
// any line record, as there is no correspondence with any user code.
- if (MI->isMetaInstruction() || MI->getFlag(MachineInstr::FrameSetup))
+ if (MI->isMetaInstruction())
+ return;
+ if (MI->getFlag(MachineInstr::FrameSetup)) {
+ // Prevent a loc from the previous block leaking into frame setup instrs.
+ if (LastAsmLine && PrevInstBB && PrevInstBB != MI->getParent())
+ RecordLineZero();
return;
+ }
+
const DebugLoc &DL = MI->getDebugLoc();
unsigned Flags = 0;
@@ -2093,11 +2118,6 @@ void DwarfDebug::beginInstruction(const MachineInstr *MI) {
LocationString);
};
- // When we emit a line-0 record, we don't update PrevInstLoc; so look at
- // the last line number actually emitted, to see if it was line 0.
- unsigned LastAsmLine =
- Asm->OutStreamer->getContext().getCurrentDwarfLoc().getLine();
-
// There may be a mixture of scopes using and not using Key Instructions.
// Not-Key-Instructions functions inlined into Key Instructions functions
// should use not-key is_stmt handling. Key Instructions functions inlined
@@ -2163,18 +2183,8 @@ void DwarfDebug::beginInstruction(const MachineInstr *MI) {
// - Instruction is at the top of a block; we don't want to inherit the
// location from the physically previous (maybe unrelated) block.
if (UnknownLocations == Enable || PrevLabel ||
- (PrevInstBB && PrevInstBB != MI->getParent())) {
- // Preserve the file and column numbers, if we can, to save space in
- // the encoded line table.
- // Do not update PrevInstLoc, it remembers the last non-0 line.
- const MDNode *Scope = nullptr;
- unsigned Column = 0;
- if (PrevInstLoc) {
- Scope = PrevInstLoc.getScope();
- Column = PrevInstLoc.getCol();
- }
- recordSourceLine(/*Line=*/0, Column, Scope, /*Flags=*/0);
- }
+ (PrevInstBB && PrevInstBB != MI->getParent()))
+ RecordLineZero();
return;
}
diff --git a/llvm/test/DebugInfo/X86/shrink-wrap-frame-setup-no-loc.mir b/llvm/test/DebugInfo/X86/shrink-wrap-frame-setup-no-loc.mir
new file mode 100644
index 0000000000000..b97e91629fba0
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/shrink-wrap-frame-setup-no-loc.mir
@@ -0,0 +1,99 @@
+# RUN: %llc_dwarf %s -o - -mtriple=x86_64-unknown-unknown --start-after=livedebugvalues | FileCheck %s
+
+## Check the line number from the ret above `.LBB0_2` doesn't leak onto the
+## frame setup instructions in the `.LBB0_2` block; `pushq %rax` should
+## explicitly get set to line zero.
+
+# CHECK: loop:
+# CHECK-NEXT: .Lfunc_begin0:
+# CHECK-NEXT: .cfi_startproc
+# CHECK-NEXT: # %bb.0:
+# CHECK-NEXT: .file 1 "/" "test.c"
+# CHECK-NEXT: .loc 1 5 16 prologue_end # test.c:5:16
+# CHECK-NEXT: testq %rax, %rax
+# CHECK-NEXT: je .LBB0_2
+# CHECK-NEXT: # %bb.1:
+# CHECK-NEXT: .loc 1 5 16 # test.c:5:16
+# CHECK-NEXT: retq
+# CHECK-NEXT: .LBB0_2:
+# -- Check the .loc below sets the current location to line 0.
+# CHECK-NEXT: .loc 1 0 16 is_stmt 0 # test.c:0:16
+# CHECK-NEXT: pushq %rax
+# CHECK-NEXT: .cfi_def_cfa_offset 16
+# CHECK-NEXT: addq $8, %rsp
+# CHECK-NEXT: .cfi_def_cfa_offset 8
+# CHECK-NEXT: .loc 1 5 16 is_stmt 1 # test.c:5:16
+# CHECK-NEXT: retq
+
+--- |
+ source_filename = "reduced.ll"
+ target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+ target triple = "x86_64-unknown-unknown"
+
+ define void @loop(i64 %i) !dbg !4 {
+ entry:
+ %cmp.not = icmp eq i64 %i, 0, !dbg !7
+ br i1 %cmp.not, label %for.body, label %for.end
+
+ for.body: ; preds = %entry
+ %puts10 = tail call i32 null(ptr null)
+ %inc = add i64 0, 0
+ br label %for.end
+
+ for.end: ; preds = %for.body, %entry
+ ret void
+ }
+
+ !llvm.dbg.cu = !{!0}
+ !llvm.module.flags = !{!3}
+
+ !0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 22.0.0git", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: !2, splitDebugInlining: false, nameTableKind: None)
+ !1 = !DIFile(filename: "test.c", directory: "/")
+ !2 = !{}
+ !3 = !{i32 2, !"Debug Info Version", i32 3}
+ !4 = distinct !DISubprogram(name: "loop", scope: !1, file: !1, line: 4, type: !5, scopeLine: 4, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2, keyInstructions: true)
+ !5 = !DISubroutineType(types: !6)
+ !6 = !{null}
+ !7 = !DILocation(line: 5, column: 16, scope: !8, atomGroup: 720, atomRank: 2)
+ !8 = distinct !DILexicalBlock(scope: !4, file: !1, line: 5, column: 9)
+...
+---
+name: loop
+alignment: 16
+tracksRegLiveness: true
+noPhis: true
+isSSA: false
+noVRegs: true
+hasFakeUses: false
+debugInstrRef: true
+tracksDebugUserValues: true
+liveins:
+ - { reg: '$rdi' }
+frameInfo:
+ stackSize: 8
+ offsetAdjustment: -8
+ maxAlignment: 1
+ adjustsStack: true
+ hasCalls: true
+ maxCallFrameSize: 0
+ isCalleeSavedInfoValid: true
+machineFunctionInfo:
+ amxProgModel: None
+body: |
+ bb.0:
+ successors: %bb.1(0x30000000), %bb.2(0x50000000)
+ liveins: $rdi
+
+ TEST64rr undef renamable $rax, undef renamable $rax, implicit-def $eflags, debug-location !7
+ JCC_1 %bb.1, 4, implicit $eflags
+
+ bb.2:
+ RET64 debug-location !7
+
+ bb.1:
+ frame-setup PUSH64r undef $rax, implicit-def $rsp, implicit $rsp
+ frame-setup CFI_INSTRUCTION def_cfa_offset 16
+ $rsp = frame-destroy ADD64ri32 $rsp, 8, implicit-def dead $eflags
+ frame-destroy CFI_INSTRUCTION def_cfa_offset 8
+ RET64 debug-location !7
+...
More information about the llvm-commits
mailing list