| Issue |
122846
|
| Summary |
`DILocation::getMergedLocation` produces invalid result while merging locations from `DILexicalBlockFile`
|
| Labels |
wrong-debug,
debuginfo
|
| Assignees |
|
| Reporter |
asl
|
Consider the following input:
```c
# 1 "1.c" 1
# 1 "1.c" 2
int foo(int a) {
int i = 0;
if ((a & 1) == 1) {
a -= 1;
# 1 "m.c" 1
# 40 "m.c"
i += a;
i -= 10*a;
i *= a*a;
# 6 "1.c" 2
} else {
a += 3;
# 1 "m.c" 1
# 40 "m.c"
i += a;
i -= 10*a;
i *= a*a;
# 9 "1.c" 2
}
return i;
}
```
The LLVM IR looks like as follows:
```llvm
...
!10 = !DIFile(filename: "1.c", directory: "/Users/asl/Projects/llvm/build/bin")
...
!27 = !DIFile(filename: "m.c", directory: "/Users/asl/Projects/llvm/build/bin")
...
!39 = distinct !DILexicalBlock(scope: !20, file: !10, line: 6, column: 9)
!40 = !DILocation(line: 40, column: 6, scope: !41)
!41 = !DILexicalBlockFile(scope: !39, file: !27, discriminator: 0)
```
Note that here we're having two nested scopes from different files.
The resulting code looks like as:
```
.loc 1 42 7 prologue_end is_stmt 1 ; 1.c:42:7
mul w9, w8, w8
.loc 1 41 3 ; 1.c:41:3
mul w8, w9, w8
Ltmp2:
.loc 1 42 3 ; 1.c:42:3
add w8, w8, w8, lsl #3
neg w0, w8
Ltmp3:
;DEBUG_VALUE: foo:i <- $w0
.loc 1 10 3 ; 1.c:10:3
ret
```
and:
```llvm
!10 = !DIFile(filename: "1.c", directory: "/Users/asl/Projects/llvm/build/bin")
...
!19 = distinct !DILexicalBlock(scope: !9, file: !10, line: 3, column: 7)
...
!22 = !DILocation(line: 42, column: 7, scope: !19)
```
So, after merging we end with invalid location info: line numbers are from one file, but file itself is different – from enclosing scope.
Indeed, it seems that `DILocation::getMergedLocation` completely ignores possibility that file could be changed and recreates the scope with invalid location info. It already has the code that handles `inlinedAt`. It think `DILexicalBlockFile` should be treated in a same way as this is essentially "textual inclusion".
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