[llvm-dev] Interleaved debug info on arm

[Carlo Kok via llvm-dev]

When compiling code with lld -O0 --lto-O0 --eh-frame-hdr I get strange interleaved line info all
over the place:
...
0x00000000000595ac 22 11 1 0 0 is_stmt 
0x00000000000595bc 25 7 1 0 0 is_stmt <<<
0x00000000000595c0 22 11 1 0 0 is_stmt 
0x00000000000595c4 25 7 1 0 0 is_stmt <<<
0x00000000000595c8 26 7 1 0 0 is_stmt

but the code only has 1 reference to line 25 and the references to line 22 all precede that:

; Function Attrs: uwtable
define hidden void @ms_t1d_ConsoleApplication479.Program4_Testni32(i32) #0 !dbg !34 {
  %2 = alloca i32
  store i32 %0, i32* %2
  call void @llvm.dbg.declare(metadata i32* %2, metadata !61, metadata !19), !dbg !63
  %3 = alloca double, !dbg !63
  store double 0.000000e+00, double* %3, !dbg !63
  %4 = alloca %WriteLineObject*, !dbg !63
  store %WriteLineObject* null, %WriteLineObject** %4, !dbg !63
  br label %5, !dbg !63

; <label>:5:                                      ; preds = %1
  call void @llvm.dbg.declare(metadata double* %3, metadata !64, metadata !19), !dbg !68
  call void @llvm.dbg.declare(metadata %WriteLineObject** %4, metadata !69, metadata !19), !dbg !68
  store double 3.140000e+00, double* %3, !dbg !71
  %6 = call i8* @__newinst(i8* bitcast ({ { i64, [30 x i8]*, i8*, [141 x i8]*, { i8*, void (%._ConsoleApplication479.Program*)*, void (i32)*, i8*, %WriteLineString* (%._ConsoleApplication479.Program*)*, i32 ()*, i8** }* }*, i8*, i8*, i8*, [16 x i8], i8*, i8*, i8*, i8* }* @_rtti_t1d_ConsoleApplication479.Program to i8*), i32 16), !dbg !72
  %7 = bitcast i8* %6 to %._ConsoleApplication479.Program*, !dbg !72
  call void @mi_t1d_ConsoleApplication479.Program5_.ctor(%._ConsoleApplication479.Program* %7) #0, !dbg !72
  %8 = bitcast %._ConsoleApplication479.Program* %7 to %WriteLineObject*, !dbg !72
  store %WriteLineObject* %8, %WriteLineObject** %4, !dbg !72
  call void @WriteLine(%WriteLineString* bitcast ({ i8*, i32, [14 x i8] }* @.str2 to %WriteLineString*)) #1, !dbg !73
  %9 = load double, double* %3, !dbg !74
  %10 = sitofp i32 1 to double, !dbg !74
  %11 = fadd double %9, %10, !dbg !74
  store double %11, double* %3, !dbg !74
  %12 = load double, double* %3, !dbg !75
  %13 = sitofp i32 1 to double, !dbg !75
  %14 = fadd double %12, %13, !dbg !75
  store double %14, double* %3, !dbg !75
  ret void, !dbg !76
}



!72 = !DILocation(line: 22, column: 11, scope: !65)
!73 = !DILocation(line: 25, column: 7, scope: !65)

full bitcode: https://gist.github.com/carlokok/aa3fab175f8afe8e4776ad6c2f5cc80a

disasm: https://gist.github.com/carlokok/ab265461b37f87a10e0853ffc4d93c77

What could possibly cause this? It's wreaking havoc with the debugger experience.

Carlo Kok
RemObjects Software