Adding test for DIMacro and DIMacroFile comparison implementation

[aaboud]

Summary

This patch contains a LIT test that covers the fix committed in rL277290.

[dblaikie]

Thanks for writing up the test!

Though this looks like a few too many CHECK lines - we usually don't check the entire contents of the output like that, so that the test is resilient to unrelated changes.

Perhaps you could show/attach the output before and after the change, so we could see what particular part changed & decide how to test just that part or the surrounding important parts?

[aaboud]

The output after the fix appears as is in the "; CHECK" lines in the LIT tests.
And here is the output before:

!llvm.dbg.cu = !{!0, !11}
!llvm.ident = !{!16, !16}
!llvm.module.flags = !{!17}

!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 4.0.0 (trunk 276746)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, macros: !3)
!1 = !DIFile(filename: "t.c", directory: "/")
!2 = !{}
!3 = !{!4, !5}
!4 = !DIMacro(type: DW_MACINFO_undef, line: 1, name: "X")
!5 = !DIMacroFile(line: 2, file: !6, nodes: !7)
!6 = !DIFile(filename: "t.h", directory: "/")
!7 = !{!8, !9}
!8 = !DIMacro(type: DW_MACINFO_define, line: 3, name: "X", value: "5")
!9 = !DIMacroFile(line: 4, file: !10)
!10 = !DIFile(filename: "t2.h", directory: "/")
!11 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 4.0.0 (trunk 276746)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, macros: !12)
!12 = !{!4, !13}
!13 = !DIMacroFile(line: 2, file: !6, nodes: !14)
!14 = !{!8, !15}
!15 = !DIMacroFile(line: 4, file: !10)
!16 = !{!"clang version 4.0.0 (trunk 276746)"}
!17 = !{i32 2, !"Debug Info Version", i32 3}

[dblaikie]

Ah, thanks - OK, so the issue was that the second DICompileUnit ended up sharing the first's DIMacroFile.
Does the test require both a top level DIMacro and a nested DIMacroFile+DIMacro? Or could a difference be observed with a smaller difference in just a DIMacro, etc?

So CHECK lines something like this would emphasize that:

; Verify that DICompileUnits don't share DIMacro info even though they are different
; CHECK: DICompileUnit
; CHECK-SAME: macros: [[MS1:![0-9]*]]
; CHECK: [[MS1]] = !{[[MF1:![0-9]*]]}
; CHECK: [[MF1]] = !DIMacroFile(
; CHECK-SAME: file: [[F1:![0-9]*]]
; CHECK: [[F1]] = !DIFile(filename: "x.h"
; CHECK: DICompileUnit
; CHECK-SAME: macros: [[MS2:![0-9]*]]
; CHECK: [[MS2]] = !{[[MF2:![0-9]*]]}
; CHECK: [[MF2]] = !DIMacroFile(
; CHECK-SAME: file: [[F2:![0-9]*]]
; CHECK: [[F2]] = !DIFile(filename: "y.h"

Side note: Is there any reason we're creating DIMacroFiles that have no macros in them? Or are they unnecessary?

[aaboud]

Side note: Is there any reason we're creating DIMacroFiles that have no macros in them? Or are they unnecessary?

1. GCC does that too.
2. It is implementation details, because we create the DIMacroFile before we parse its content, thus at that point we do not know if it will contain macros or not.

[aaboud]

In D23056#504984, @dblaikie wrote:

Ah, thanks - OK, so the issue was that the second DICompileUnit ended up sharing the first's DIMacroFile.

I just noticed that you got me wrong.
The issue is that the second DICimpileUnit ended up not sharing the first's DIMacroFile.

Anyway, I will try improve the test using the above as an example.

[aaboud]

Reduced and simplified the LIT test.

test/DebugInfo/macro_link.ll

+; RUN: llvm-link %s %s -S -o -| FileCheck %s
+
+; This test checks that DIMacro and DIMacroFile comaprison works correctly.
+
+; CHECK: !llvm.dbg.cu = !{[[CU1:![0-9]*]], [[CU2:![0-9]*]]}
+
+; CHECK: [[CU1]] = distinct !DICompileUnit
+; CHECK-SAME: macros: [[MS1:![0-9]*]]
+; CHECK: [[F1:![0-9]*]] = !DIFile(filename: "t.c"
+; CHECK: [[MS1]] = !{[[MF1:![0-9]*]]}
+; CHECK: [[MF1]] = !DIMacroFile(
+; CHECK-SAME: file: [[F1]], nodes: [[MS2:![0-9]*]])
+; CHECK: [[MS2]] = !{[[M1:![0-9]*]]}
+; CHECK: [[M1]] = !DIMacro(type: DW_MACINFO_define, line: 3, name: "X", value: "5")
+; CHECK: [[CU2]] = distinct !DICompileUnit
+; CHECK-SAME: macros: [[MS1]]
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!7}
+!llvm.ident = !{!8}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 4.0.0 (trunk 276746)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, macros: !3)
+!1 = !DIFile(filename: "t.c", directory: "/")
+!2 = !{}
+!3 = !{!4}
+!4 = !DIMacroFile(line: 0, file: !1, nodes: !5)
+!5 = !{!6}
+!6 = !DIMacro(type: DW_MACINFO_define, line: 3, name: "X", value: "5")
+!7 = !{i32 2, !"Debug Info Version", i32 3}
+!8 = !{!"clang version 4.0.0 (trunk 276746)"}