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llvm-mirror/test/DebugInfo/inline-no-debug-info.ll
David Blaikie 5ab2c04898 DebugInfo: Use distinct inlinedAt MDLocations to avoid separate inlined calls being coalesced
When two calls from the same MDLocation are inlined they currently get
treated as one inlined function call (creating difficulty debugging,
duplicate variables, etc).

Clang worked around this by including column information on inline calls
which doesn't address LTO inlining or calls to the same function from
the same line and column (such as through a macro). It also didn't
address ctor and member function calls.

By making the inlinedAt locations distinct, every call site has an
explicitly distinct location that cannot be coalesced with any other
call.

This can produce linearly (2x in the worst case where every call is
inlined and the call instruction has a non-call instruction at the same
location) more debug locations. Any increase beyond that are in cases
where the Clang workaround was insufficient and the new scheme is
creating necessary distinct nodes that were being erroneously coalesced
previously.

After this change to LLVM the incomplete workarounds in Clang. That
should reduce the number of debug locations (in a build without column
info, the default on Darwin, not the default on Linux) by not creating
pseudo-distinct locations for every call to an inline function.

(oh, and I made the inlined-at chain rebuilding iterative instead of
recursive because I was having trouble wrapping my head around it the
way it was - open to discussion on the right design for that function
(including going back to a recursive solution))

llvm-svn: 226736
2015-01-21 22:57:29 +00:00

71 lines
2.8 KiB
LLVM

; RUN: opt < %s -inline -S | FileCheck %s
; This was generated from the following source:
; int a, b;
; __attribute__((__always_inline__)) static void callee2() { b = 2; }
; __attribute__((__nodebug__)) void callee() { a = 1; callee2(); }
; void caller() { callee(); }
; by running
; clang -S test.c -emit-llvm -O1 -gline-tables-only -fno-strict-aliasing
; CHECK-LABEL: @caller(
; This instruction did not have a !dbg metadata in the callee.
; CHECK: store i32 1, {{.*}}, !dbg [[A:!.*]]
; This instruction came from callee with a !dbg metadata.
; CHECK: store i32 2, {{.*}}, !dbg [[B:!.*]]
; The remaining instruction from the caller.
; CHECK: ret void, !dbg [[A]]
; Debug location of the code in caller() and of the inlined code that did not
; have any debug location before.
; CHECK-DAG: [[A]] = !MDLocation(line: 4, scope: !{{[0-9]+}})
; Debug location of the inlined code.
; CHECK-DAG: [[B]] = !MDLocation(line: 2, scope: !{{[0-9]+}}, inlinedAt: [[A_INL:![0-9]*]])
; CHECK-DAG: [[A_INL]] = distinct !MDLocation(line: 4, scope: !{{[0-9]+}})
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
@a = common global i32 0, align 4
@b = common global i32 0, align 4
; Function Attrs: nounwind uwtable
define void @callee() #0 {
entry:
store i32 1, i32* @a, align 4
store i32 2, i32* @b, align 4, !dbg !11
ret void
}
; Function Attrs: nounwind uwtable
define void @caller() #0 {
entry:
tail call void @callee(), !dbg !12
ret void, !dbg !12
}
attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!8, !9}
!llvm.ident = !{!10}
!0 = !{!"0x11\0012\00clang version 3.5.0 (210174)\001\00\000\00\002", !1, !2, !2, !3, !2, !2} ; [ DW_TAG_compile_unit ] [/code/llvm/build0/test.c] [DW_LANG_C99]
!1 = !{!"test.c", !"/code/llvm/build0"}
!2 = !{}
!3 = !{!4, !7}
!4 = !{!"0x2e\00caller\00caller\00\004\000\001\000\006\000\001\004", !1, !5, !6, null, void ()* @caller, null, null, !2} ; [ DW_TAG_subprogram ] [line 4] [def] [caller]
!5 = !{!"0x29", !1} ; [ DW_TAG_file_type ] [/code/llvm/build0/test.c]
!6 = !{!"0x15\00\000\000\000\000\000\000", i32 0, null, null, !2, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
!7 = !{!"0x2e\00callee2\00callee2\00\002\001\001\000\006\000\001\002", !1, !5, !6, null, null, null, null, !2} ; [ DW_TAG_subprogram ] [line 2] [local] [def] [callee2]
!8 = !{i32 2, !"Dwarf Version", i32 4}
!9 = !{i32 2, !"Debug Info Version", i32 2}
!10 = !{!"clang version 3.5.0 (210174)"}
!11 = !MDLocation(line: 2, scope: !7)
!12 = !MDLocation(line: 4, scope: !4)