DebugInfo: Don't lose unreferenced non-trivial by-value parameters

A FastISel optimization was causing us to emit no information for such
parameters & when they go missing we end up emitting a different
function type. By avoiding that shortcut we not only get types correct
(very important) but also location information (handy) - even if it's
only live at the start of a function & may be clobbered later.

Reviewed/discussion by Evan Cheng & Dan Gohman.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184604 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 72 insertions, 1 deletions

diff --git a/test/CodeGen/ARM/fast-isel-call.ll b/test/CodeGen/ARM/fast-isel-call.ll
index 3833043ad7..d10a381df6 100644
--- a/test/CodeGen/ARM/fast-isel-call.ll
+++ b/test/CodeGen/ARM/fast-isel-call.ll
@@ -92,7 +92,7 @@ declare signext i8 @t7();
 declare zeroext i8 @t8();
 declare zeroext i1 @t9();
 
-define i32 @t10(i32 %argc, i8** nocapture %argv) {
+define i32 @t10() {
 entry:
 ; ARM: @t10
 ; ARM: movw [[R0:l?r[0-9]*]], #0
diff --git a/test/DebugInfo/arguments.ll b/test/DebugInfo/arguments.ll
new file mode 100644
index 0000000000..30bc870547
--- /dev/null
+++ b/test/DebugInfo/arguments.ll
@@ -0,0 +1,71 @@
+; REQUIRES: object-emission
+
+; RUN: llc -O0 -filetype=obj < %s > %t
+; RUN: llvm-dwarfdump %t | FileCheck %s
+
+; IR generated from clang -g with the following source:
+; struct foo {
+;   foo(const foo&);
+;   int i;
+; };
+;
+; void func(foo f, foo g) {
+;   f.i++;
+; }
+
+; CHECK: debug_info contents
+; CHECK: DW_TAG_subprogram
+; CHECK-NEXT: DW_AT_MIPS_linkage_name{{.*}}"_Z4func3fooS_"
+; CHECK-NOT: NULL
+; CHECK: DW_TAG_formal_parameter
+; CHECK-NEXT: DW_AT_name{{.*}}"f"
+; CHECK-NOT: NULL
+; CHECK: DW_TAG_formal_parameter
+; CHECK-NEXT: DW_AT_name{{.*}}"g"
+
+%struct.foo = type { i32 }
+
+; Function Attrs: nounwind uwtable
+define void @_Z4func3fooS_(%struct.foo* %f, %struct.foo* %g) #0 {
+entry:
+  call void @llvm.dbg.declare(metadata !{%struct.foo* %f}, metadata !19), !dbg !20
+  call void @llvm.dbg.declare(metadata !{%struct.foo* %g}, metadata !21), !dbg !20
+  %i = getelementptr inbounds %struct.foo* %f, i32 0, i32 0, !dbg !22
+  %0 = load i32* %i, align 4, !dbg !22
+  %inc = add nsw i32 %0, 1, !dbg !22
+  store i32 %inc, i32* %i, align 4, !dbg !22
+  ret void, !dbg !23
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata) #1
+
+attributes #0 = { nounwind 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 }
+
+!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 ] [/usr/local/google/home/blaikie/dev/scratch/scratch.cpp] [DW_LANG_C_plus_plus]
+!1 = metadata !{metadata !"scratch.cpp", metadata !"/usr/local/google/home/blaikie/dev/scratch"}
+!2 = metadata !{i32 0}
+!3 = metadata !{metadata !4}
+!4 = metadata !{i32 786478, metadata !1, metadata !5, metadata !"func", metadata !"func", metadata !"_Z4func3fooS_", i32 6, metadata !6, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, void (%struct.foo*, %struct.foo*)* @_Z4func3fooS_, null, null, metadata !2, i32 6} ; [ DW_TAG_subprogram ] [line 6] [def] [func]
+!5 = metadata !{i32 786473, metadata !1}          ; [ DW_TAG_file_type ] [/usr/local/google/home/blaikie/dev/scratch/scratch.cpp]
+!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 !{null, metadata !8, metadata !8}
+!8 = metadata !{i32 786451, metadata !1, null, metadata !"foo", i32 1, i64 32, i64 32, i32 0, i32 0, null, metadata !9, i32 0, null, null} ; [ DW_TAG_structure_type ] [foo] [line 1, size 32, align 32, offset 0] [from ]
+!9 = metadata !{metadata !10, metadata !12}
+!10 = metadata !{i32 786445, metadata !1, metadata !8, metadata !"i", i32 3, i64 32, i64 32, i64 0, i32 0, metadata !11} ; [ DW_TAG_member ] [i] [line 3, size 32, align 32, offset 0] [from int]
+!11 = metadata !{i32 786468, null, null, metadata !"int", i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
+!12 = metadata !{i32 786478, metadata !1, metadata !8, metadata !"foo", metadata !"foo", metadata !"", i32 2, metadata !13, i1 false, i1 false, i32 0, i32 0, null, i32 256, i1 false, null, null, i32 0, metadata !18, i32 2} ; [ DW_TAG_subprogram ] [line 2] [foo]
+!13 = metadata !{i32 786453, i32 0, i32 0, metadata !"", i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !14, i32 0, i32 0} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
+!14 = metadata !{null, metadata !15, metadata !16}
+!15 = 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]
+!16 = metadata !{i32 786448, null, null, null, i32 0, i64 0, i64 0, i64 0, i32 0, metadata !17} ; [ DW_TAG_reference_type ] [line 0, size 0, align 0, offset 0] [from ]
+!17 = 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]
+!18 = metadata !{i32 786468}
+!19 = metadata !{i32 786689, metadata !4, metadata !"f", metadata !5, i32 16777222, metadata !8, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [f] [line 6]
+!20 = metadata !{i32 6, i32 0, metadata !4, null}
+!21 = metadata !{i32 786689, metadata !4, metadata !"g", metadata !5, i32 33554438, metadata !8, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [g] [line 6]
+!22 = metadata !{i32 7, i32 0, metadata !4, null}
+!23 = metadata !{i32 8, i32 0, metadata !4, null} ; [ DW_TAG_imported_declaration ]