1 files changed, 81 insertions, 0 deletions
diff --git a/llvm/test/DebugInfo/Generic/dead-argument-order.ll b/llvm/test/DebugInfo/Generic/dead-argument-order.ll
new file mode 100644
index 00000000000..b3ae5fe5e31
--- /dev/null
+++ b/llvm/test/DebugInfo/Generic/dead-argument-order.ll
@@ -0,0 +1,81 @@
+; REQUIRES: object-emission
+
+; RUN: %llc_dwarf -O0 -filetype=obj < %s | llvm-dwarfdump -debug-dump=info - | FileCheck %s
+
+; Built from the following source with clang -O1
+; struct S { int i; };
+; int function(struct S s, int i) { return s.i + i; }
+
+; Due to the X86_64 ABI, 's' is passed in registers and once optimized, the
+; entirety of 's' is never reconstituted, since only the int is required, and
+; thus the variable's location is unknown/dead to debug info.
+
+; Future/current work should enable us to describe partial variables, which, in
+; this case, happens to be the entire variable.
+
+; CHECK: DW_TAG_subprogram
+; CHECK-NOT: DW_TAG
+; CHECK:   DW_AT_name {{.*}} "function"
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK:   DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK:     DW_AT_name {{.*}} "s"
+; CHECK-NOT: DW_TAG
+; FIXME: Even though 's' is never reconstituted into a struct, the one member
+; variable is still live and used, and so we should be able to describe 's's
+; location as the location of that int.
+; CHECK-NOT: DW_AT_location
+; CHECK-NOT: {{DW_TAG|NULL}}
+; CHECK:   DW_TAG_formal_parameter
+; CHECK-NOT: DW_TAG
+; CHECK:     DW_AT_location
+; CHECK-NOT: DW_TAG
+; CHECK:     DW_AT_name {{.*}} "i"
+
+
+%struct.S = type { i32 }
+
+; Function Attrs: nounwind readnone uwtable
+define i32 @_Z8function1Si(i32 %s.coerce, i32 %i) #0 {
+entry:
+  tail call void @llvm.dbg.declare(metadata %struct.S* undef, metadata !14, metadata !DIExpression()), !dbg !20
+  tail call void @llvm.dbg.value(metadata i32 %i, i64 0, metadata !15, metadata !DIExpression()), !dbg !20
+  %add = add nsw i32 %i, %s.coerce, !dbg !20
+  ret i32 %add, !dbg !20
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #1
+
+attributes #0 = { nounwind readnone uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!16, !17}
+!llvm.ident = !{!18}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.5.0 ", isOptimized: true, emissionKind: 1, file: !1, enums: !2, retainedTypes: !3, subprograms: !8, globals: !2, imports: !2)
+!1 = !DIFile(filename: "dead-argument-order.cpp", directory: "/tmp/dbginfo")
+!2 = !{}
+!3 = !{!4}
+!4 = !DICompositeType(tag: DW_TAG_structure_type, name: "S", line: 1, size: 32, align: 32, file: !1, elements: !5, identifier: "_ZTS1S")
+!5 = !{!6}
+!6 = !DIDerivedType(tag: DW_TAG_member, name: "i", line: 1, size: 32, align: 32, file: !1, scope: !"_ZTS1S", baseType: !7)
+!7 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!8 = !{!9}
+!9 = distinct !DISubprogram(name: "function", linkageName: "_Z8function1Si", line: 2, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, scopeLine: 2, file: !1, scope: !10, type: !11, function: i32 (i32, i32)* @_Z8function1Si, variables: !13)
+!10 = !DIFile(filename: "dead-argument-order.cpp", directory: "/tmp/dbginfo")
+!11 = !DISubroutineType(types: !12)
+!12 = !{!7, !4, !7}
+!13 = !{!14, !15}
+!14 = !DILocalVariable(name: "s", line: 2, arg: 1, scope: !9, file: !10, type: !"_ZTS1S")
+!15 = !DILocalVariable(name: "i", line: 2, arg: 2, scope: !9, file: !10, type: !7)
+!16 = !{i32 2, !"Dwarf Version", i32 4}
+!17 = !{i32 2, !"Debug Info Version", i32 3}
+!18 = !{!"clang version 3.5.0 "}
+!19 = !{%struct.S* undef}
+!20 = !DILocation(line: 2, scope: !9)
+