Adrian Prantl 02474a32eb Move the complex address expression out of DIVariable and into an extra
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.

Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.

By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.

The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)

This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.

What this patch doesn't do:

This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.

http://reviews.llvm.org/D4919
rdar://problem/17994491

Thanks to dblaikie and dexonsmith for reviewing this patch!

Note: I accidentally committed a bogus older version of this patch previously.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218787 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-01 18:55:02 +00:00

36 lines
2.1 KiB
LLVM

; RUN: llc %s -mtriple=x86_64-pc-linux-gnu -O0 -o - | FileCheck %s
; We are testing that a value in a 16 bit register gets reported as
; being in its superregister.
; CHECK: .byte 80 # super-register
; CHECK-NEXT: # DW_OP_reg0
; CHECK-NEXT: .byte 147 # DW_OP_piece
; CHECK-NEXT: .byte 2 # 2
define i16 @f(i16 signext %zzz) nounwind {
entry:
call void @llvm.dbg.value(metadata !{i16 %zzz}, i64 0, metadata !0, metadata !{i32 786690})
%conv = sext i16 %zzz to i32, !dbg !7
%conv1 = trunc i32 %conv to i16
ret i16 %conv1
}
declare void @llvm.dbg.value(metadata, i64, metadata, metadata) nounwind readnone
!llvm.dbg.cu = !{!3}
!llvm.module.flags = !{!11}
!9 = metadata !{metadata !1}
!0 = metadata !{i32 786689, metadata !1, metadata !"zzz", metadata !2, i32 16777219, metadata !6, i32 0, null} ; [ DW_TAG_arg_variable ]
!1 = metadata !{i32 786478, metadata !10, metadata !2, metadata !"f", metadata !"f", metadata !"", i32 3, metadata !4, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i16 (i16)* @f, null, null, null, i32 3} ; [ DW_TAG_subprogram ] [line 3] [def] [f]
!2 = metadata !{i32 786473, metadata !10} ; [ DW_TAG_file_type ]
!3 = metadata !{i32 786449, metadata !10, i32 12, metadata !"clang version 3.0 ()", i1 false, metadata !"", i32 0, metadata !5, metadata !5, metadata !9, null, null, metadata !"", i32 1} ; [ DW_TAG_compile_unit ]
!4 = metadata !{i32 786453, metadata !10, metadata !2, metadata !"", i32 0, i64 0, i64 0, i32 0, i32 0, null, metadata !5, i32 0, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
!5 = metadata !{null}
!6 = metadata !{i32 786468, null, metadata !3, metadata !"short", i32 0, i64 16, i64 16, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
!7 = metadata !{i32 4, i32 22, metadata !8, null}
!8 = metadata !{i32 786443, metadata !10, metadata !1, i32 3, i32 19, i32 0} ; [ DW_TAG_lexical_block ]
!10 = metadata !{metadata !"/home/espindola/llvm/test.c", metadata !"/home/espindola/tmpfs/build"}
!11 = metadata !{i32 1, metadata !"Debug Info Version", i32 1}