[DWARF] Support block-form DW_AT_GNU_call_site_target_clobbered

[OCHyams]

Not sure whether this comes up in practice, but I noticed a switch block I missed in #171183 and #172167

[llvmbot]

@llvm/pr-subscribers-debuginfo

Author: Orlando Cazalet-Hyams (OCHyams)

Changes

Not sure whether this comes up in practice, but I noticed a switch block I missed in #171183 and #172167

---

Full diff: https://github.com/llvm/llvm-project/pull/172450.diff

2 Files Affected:

• (modified) llvm/lib/DebugInfo/DWARF/DWARFDie.cpp (+1)
• (added) llvm/test/DebugInfo/MIR/X86/dwarf-dump-call-target-block.mir (+70)

diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
index a10becb252006..cd8a2b305a0f9 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDie.cpp
@@ -853,6 +853,7 @@ bool DWARFAttribute::mayHaveLocationExpr(dwarf::Attribute Attr) {
   // Extensions.
   case DW_AT_GNU_call_site_value:
   case DW_AT_GNU_call_site_target:
+  case DW_AT_GNU_call_site_target_clobbered:
     return true;
   default:
     return false;
diff --git a/llvm/test/DebugInfo/MIR/X86/dwarf-dump-call-target-block.mir b/llvm/test/DebugInfo/MIR/X86/dwarf-dump-call-target-block.mir
new file mode 100644
index 0000000000000..9fbc5e5dc6857
--- /dev/null
+++ b/llvm/test/DebugInfo/MIR/X86/dwarf-dump-call-target-block.mir
@@ -0,0 +1,70 @@
+# RUN: llc %s -start-after=livedebugvalues --filetype=obj -o - | llvm-dwarfdump - -v
+
+## Contrived test: -gdwarf-3 -ggdb and hand-modified IR adding DISubprogram
+## flag DIFlagAllCallsDescribed to force call site emission using DW_FORM_block,
+## to check block form expressions are handled.
+
+# CHECK: DW_AT_GNU_call_site_target_clobbered [DW_FORM_block1] (DW_OP_breg5 RDI+0)
+
+--- |
+  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"
+
+  define dso_local void @_Z8call_memPPFvvE(ptr noundef readonly captures(none) %f) local_unnamed_addr !dbg !5 {
+  entry:
+    %0 = load ptr, ptr %f, align 8
+    call void %0(), !dbg !13
+    ret void
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!2, !3}
+  !llvm.ident = !{!4}
+
+  !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 22.0.0git", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+  !1 = !DIFile(filename: "test.cpp", directory: "/")
+  !2 = !{i32 7, !"Dwarf Version", i32 3}
+  !3 = !{i32 2, !"Debug Info Version", i32 3}
+  !4 = !{!"clang version 22.0.0git"}
+  !5 = distinct !DISubprogram(name: "call_mem", linkageName: "_Z8call_memPPFvvE", scope: !1, file: !1, line: 1, type: !6, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)
+  !6 = !DISubroutineType(types: !7)
+  !7 = !{null, !8}
+  !8 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !9, size: 64)
+  !9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64)
+  !10 = !DISubroutineType(types: !11)
+  !11 = !{null}
+  !12 = !{}
+  !13 = !DILocation(line: 3, scope: !5)
+...
+---
+name:            _Z8call_memPPFvvE
+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.entry:
+    liveins: $rdi
+
+    frame-setup PUSH64r undef $rax, implicit-def $rsp, implicit $rsp
+    frame-setup CFI_INSTRUCTION def_cfa_offset 16
+    CALL64m killed renamable $rdi, 1, $noreg, 0, $noreg, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, debug-location !13 :: (load (s64) from %ir.f)
+    $rax = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+    frame-destroy CFI_INSTRUCTION def_cfa_offset 8
+    RET64
+...

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[dstenb]

LGTM!