https://bugs.llvm.org/show_bug.cgi?id=39896
Bug ID: 39896
Summary: Lowering loses information about debug variable
assignment.
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Keywords: wrong-debug
Severity: enhancement
Priority: P
Component: DebugInfo
Assignee: unassignedb...@nondot.org
Reporter: dav...@freebsd.org
CC: carlos.alberto.enc...@gmail.com,
greg.bedw...@sony.com, jdevliegh...@apple.com,
jeremy.morse.l...@gmail.com, keith.wal...@arm.com,
llvm-bugs@lists.llvm.org,
paul_robin...@playstation.sony.com
Created attachment 21196
--> https://bugs.llvm.org/attachment.cgi?id=21196&action=edit
testcase
The following IR debug instruction/metadata (please see attachment for the full
file):
@a = global i8 25, align 1, !dbg !0
; Function Attrs: nounwind ssp uwtable
define signext i16 @b() #0 !dbg !12 {
entry:
call void @llvm.dbg.value(metadata i16 23680, metadata !17, metadata
!DIExpression()), !dbg !18
%0 = load i8, i8* @a, align 1, !dbg !19, !tbaa !20
%conv = sext i8 %0 to i16, !dbg !19
call void @llvm.dbg.value(metadata i16 %conv, metadata !17, metadata
!DIExpression()), !dbg !18
%call = call i32 (...) @optimize_me_not(), !dbg !23
%1 = load i8, i8* @a, align 1, !dbg !24, !tbaa !20
%conv1 = sext i8 %1 to i16, !dbg !24
ret i16 %conv1, !dbg !25
}
Gets lowered into:
$ ./llc -filetype=obj ./baciotto.ll -o Palatino
$ dwarfdump ./patatino
[…]
0x00000046: TAG_subprogram [4] *
AT_low_pc( 0x0000000000000000 )
AT_high_pc( 0x00000014 )
AT_frame_base( rbp )
Unknown DW_AT constant: 0x7a( true )
AT_name( "b" )
AT_decl_file( "/Users/dcci/work/llvm/build-debug/bin/run.c" )
AT_decl_line( 2 )
AT_type( {0x00000095} ( short ) )
AT_external( true )
AT_APPLE_optimized( true )
0x0000005f: TAG_variable [5]
AT_const_value( 0x0000000000005c80 )
AT_name( "i" )
AT_decl_file(
"/Users/dcci/work/llvm/build-debug/bin/run.c" )
AT_decl_line( 3 )
AT_type( {0x00000095} ( short ) )
0x0000006d: NULL
Somehow, somewhere in the backend or in MC we loose track that the variable
gets reassigned to the value loaded from the global @a. This degrades the debug
info quality, printing the wrong value.
--
You are receiving this mail because:
You are on the CC list for the bug._______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
