[CodeView] Fix inline sites that are missing code offsets.

[akhuang]

Summary

When an inline site has a starting code offset of 0, we sometimes
don't emit the starting offset.

This patch removes the case that emits a BinaryAnnotationOpCode::ChangeLineOffset when the code offset is 0. These cases will just go to the next case that emits a BinaryAnnotationOpCode::ChangeCodeOffsetAndLineOffset.

Bug: https://bugs.llvm.org/show_bug.cgi?id=48377

[dblaikie]

llvm/test/DebugInfo/COFF/inline-site-syms.ll

8–13

I'd probably suggest a simpler (it's probably about the same in IR, but simpler in terms of language features, names, etc) test case for inlining, something like:

void f1();
__attribute__((always_inline)) void f2() {
  f1();
}
void f3() {
  f2();
}

If that's adequate.

[rnk]

Is this a bug in llvm-symbolizer? What does windbg think if you stop on the first instruction of such an inline call site?

Looks like other test expectations need to be updated as well.

[akhuang]

Oh, I do need to fix the existing tests. Actually, the test I wrote probably belongs in that test directory.

I don't think it's a bug in llvm-symbolizer since I don't think we can assume that an inline site starts at offset 0 if it's not specified. llvm-symbolizer with DIA also fails to find the inline site here; I haven't looked at what windbg does.

[akhuang]

llvm/test/DebugInfo/COFF/inline-site-syms.ll

8–13

yep, I mostly used this particular code because the offset of the inline site in the function happens to be 0. But I suppose this should actually have been an assembly test and changing the existing tests should be adequate test coverage for this--

[akhuang]

Update failing tests

[rnk]

lgtm

llvm/lib/MC/MCCodeView.cpp

if (CurSourceLoc.File != LastSourceLoc.File) {
                                 ->getValue();
       compressAnnotation(BinaryAnnotationsOpCode::ChangeFile, Buffer);
       compressAnnotation(FileOffset, Buffer);
     }
 
     int LineDelta = CurSourceLoc.Line - LastSourceLoc.Line;
     unsigned EncodedLineDelta = encodeSignedNumber(LineDelta);
     unsigned CodeDelta = computeLabelDiff(Layout, LastLabel, Loc.getLabel());
-    if (CodeDelta == 0 && LineDelta != 0) {
-      compressAnnotation(BinaryAnnotationsOpCode::ChangeLineOffset, Buffer);
-      compressAnnotation(EncodedLineDelta, Buffer);
-    } else if (EncodedLineDelta < 0x8 && CodeDelta <= 0xf) {
+    if (EncodedLineDelta < 0x8 && CodeDelta <= 0xf) {
       // The ChangeCodeOffsetAndLineOffset combination opcode is used when the
       // encoded line delta uses 3 or fewer set bits and the code offset fits
       // in one nibble.
       unsigned Operand = (EncodedLineDelta << 4) | CodeDelta;
       compressAnnotation(BinaryAnnotationsOpCode::ChangeCodeOffsetAndLineOffset,
                          Buffer);
       compressAnnotation(Operand, Buffer);
     } else {

llvm/test/DebugInfo/COFF/inline-site-syms.ll

+; RUN: llc -mtriple=x86_64-windows-msvc -filetype=obj %s -o %t.o
+; RUN: llvm-pdbutil dump -symbols %t.o | FileCheck %s
+
+; This LL file was generated by running
+;   clang -cc1 -triple x86_64-windows-msvc -gcodeview
+; on the following code:
+;   -debug-info-kind=line-tables-only -emit-obj
+; int test(int x) {
+;   auto f = [](int x) {
+;     return x * 100;
+;   };
+;   return f(x);
+; }
+
+; Test that an inline site with a starting code offset of 0 contains
+; that code offset in the inline site symbol.
+; CHECK:      S_INLINESITE [size = 20]
+; CHECK-NEXT: inlinee ={{.*}} (test(int)::(anonymous class)::
+; CHECK-NEXT: code 0x0 (+0x0) line 1 (+1)
+; CHECK-NEXT: code end 0x3 (+0x3)
+
+; ModuleID = 't.cpp'
+source_filename = "t.cpp"
+target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-windows-msvc"
+
+define dso_local i32 @"?test@@YAHH@Z"(i32 %x) local_unnamed_addr !dbg !7 {
+entry:
+  %mul.i = mul nsw i32 %x, 100, !dbg !10
+  ret i32 %mul.i, !dbg !13
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 12.0.0 (https://github.com/llvm/llvm-project.git d45cf3789d141ab8b623cdb3585dbf3075eb1b4c)", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "<stdin>", directory: "C:\\testpath")
+!2 = !{}
+!3 = !{i32 2, !"CodeView", i32 1}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 2}
+!6 = !{!"clang version 12.0.0 (https://github.com/llvm/llvm-project.git d45cf3789d141ab8b623cdb3585dbf3075eb1b4c)"}
+!7 = distinct !DISubprogram(name: "test", scope: !8, file: !8, line: 1, type: !9, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!8 = !DIFile(filename: "t.cpp", directory: "C:\\src\\tests\\sbox-integration\\small-repro-1", checksumkind: CSK_MD5, checksum: "58386de68a85e3992bf5f17550990d68")
+!9 = !DISubroutineType(types: !2)
+!10 = !DILocation(line: 3, column: 14, scope: !11, inlinedAt: !12)
+!11 = distinct !DISubprogram(name: "test(int)::(anonymous class)::operator()", scope: !8, file: !8, line: 2, type: !9, scopeLine: 2, flags: DIFlagPrototyped, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!12 = distinct !DILocation(line: 5, column: 10, scope: !7)
+!13 = !DILocation(line: 5, column: 3, scope: !7)