DebugInfo: PR14763/r183329 correct the location of indirect parameters

We had been papering over a problem with location info for non-trivial
types passed by value by emitting their type as references (this caused
the debugger to interpret the location information correctly, but broke
the type of the function). r183329 corrected the type information but
lead to the debugger interpreting the pointer parameter as the value -
the debug info describing the location needed an extra dereference.

Use a new flag in DIVariable to add the extra indirection (either by
promoting an existing DW_OP_reg (parameter passed in a register) to
DW_OP_breg + 0 or by adding DW_OP_deref to an existing DW_OP_breg + n
(parameter passed on the stack).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184368 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 70 insertions, 0 deletions

diff --git a/test/DebugInfo/X86/parameters.ll b/test/DebugInfo/X86/parameters.ll
new file mode 100644
index 0000000000..e427fa3e74
--- /dev/null
+++ b/test/DebugInfo/X86/parameters.ll
@@ -0,0 +1,70 @@
+; REQUIRES: object-emission
+;
+; RUN: llc -O0 -filetype=obj < %s > %t
+; RUN: llvm-dwarfdump %t | FileCheck %s
+
+; Test case derived from compiling the following source with clang -g:
+;
+; namespace pr14763 {
+; struct foo {
+;   foo(const foo&);
+; };
+;
+; foo func(foo f) {
+;   return f; // reference 'f' for now because otherwise we hit another bug
+; }
+; }
+
+; CHECK: debug_info contents
+; CHECK: DW_AT_name{{.*}} = "f"
+; CHECK: DW_AT_location{{.*}}([[LOC:0x[0-9]*]])
+; CHECK: debug_loc contents
+; CHECK-NEXT: [[LOC]]: Begining
+; CHECK-NEXT:            Ending
+; 0x74 is DW_OP_breg0 + 4, showing that the parameter is accessed indirectly
+; (with a zero offset) from the register parameter
+; CHECK-NEXT: Location description: 74 00
+
+%"struct.pr14763::foo" = type { i8 }
+
+; Function Attrs: uwtable
+define void @_ZN7pr147634funcENS_3fooE(%"struct.pr14763::foo"* noalias sret %agg.result, %"struct.pr14763::foo"* %f) #0 {
+entry:
+  call void @llvm.dbg.declare(metadata !{%"struct.pr14763::foo"* %f}, metadata !17), !dbg !20
+  call void @_ZN7pr147633fooC1ERKS0_(%"struct.pr14763::foo"* %agg.result, %"struct.pr14763::foo"* %f), !dbg !21
+  ret void, !dbg !21
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata) #1
+
+declare void @_ZN7pr147633fooC1ERKS0_(%"struct.pr14763::foo"*, %"struct.pr14763::foo"*) #2
+
+attributes #0 = { uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone }
+attributes #2 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.dbg.cu = !{!0}
+
+!0 = metadata !{i32 786449, metadata !1, i32 4, metadata !"clang version 3.4 ", i1 false, metadata !"", i32 0, metadata !2, metadata !2, metadata !3, metadata !2, metadata !2, metadata !""} ; [ DW_TAG_compile_unit ] [/tmp/pass.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"pass.cpp", metadata !"/tmp"}
+!2 = metadata !{i32 0}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"func", metadata !"func", metadata !"_ZN7pr147634funcENS_3fooE", i32 6, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, void (%"struct.pr14763::foo"*, %"struct.pr14763::foo"*)* @_ZN7pr147634funcENS_3fooE, null, null, metadata !2, i32 6} ; [ DW_TAG_subprogram ] [line 6] [def] [func]
+!5 = metadata !{i32 786489, metadata !1, null, metadata !"pr14763", i32 1} ; [ DW_TAG_namespace ] [pr14763] [line 1]
+!6 = metadata !{i32 786453, i32 0, i32 0, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !7, i32 0, i32 0} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!7 = metadata !{metadata !8, metadata !8}
+!8 = metadata !{i32 786451, metadata !1, metadata !5, metadata !"foo", i32 2, i64 8, i64 8, i32 0, i32 0, null, metadata !9, i32 0, null, null} ; [ DW_TAG_structure_type ] [foo] [line 2, size 8, align 8, offset 0] [from ]
+!9 = metadata !{metadata !10}
+!10 = metadata !{i32 786478, metadata !1, metadata !8, metadata !"foo", metadata !"foo", metadata !"", i32 3, metadata !11, i1 false, i1 false, i32 0, i32 0, null, i32 256, i1 false, null, null, i32 0, metadata !16, i32 3} ; [ DW_TAG_subprogram ] [line 3] [foo]
+!11 = metadata !{i32 786453, i32 0, i32 0, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !12, i32 0, i32 0} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!12 = metadata !{null, metadata !13, metadata !14}
+!13 = metadata !{i32 786447, i32 0, i32 0, metadata !"", i32 0, i64 64, i64 64, i64 0, i32 1088, metadata !8} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [artificial] [from foo]
+!14 = metadata !{i32 786448, null, null, null, i32 0, i64 0, i64 0, i64 0, i32 0, metadata !15} ; [ DW_TAG_reference_type ] [line 0, size 0, align 0, offset 0] [from ]
+!15 = metadata !{i32 786470, null, null, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, metadata !8} ; [ DW_TAG_const_type ] [line 0, size 0, align 0, offset 0] [from foo]
+!16 = metadata !{i32 786468}
+!17 = metadata !{i32 786689, metadata !4, metadata !"f", metadata !18, i32 16777222, metadata !19, i32 8192, i32 0} ; [ DW_TAG_arg_variable ] [f] [line 6]
+!18 = metadata !{i32 786473, metadata !1}         ; [ DW_TAG_file_type ] [/tmp/pass.cpp]
+!19 = metadata !{i32 786448, null, null, null, i32 0, i64 0, i64 0, i64 0, i32 0, metadata !8} ; [ DW_TAG_reference_type ] [line 0, size 0, align 0, offset 0] [from foo]
+!20 = metadata !{i32 6, i32 0, metadata !4, null}
+!21 = metadata !{i32 7, i32 0, metadata !4, null}