https://llvm.org/bugs/show_bug.cgi?id=30553
Bug ID: 30553
Summary: Debug info generated for arrays is not what GDB
expects (not as good as GCC's)
Product: new-bugs
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: new bugs
Assignee: unassignedb...@nondot.org
Reporter: cmt...@google.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
There is a very annoying difference in the way GCC & LLVM generate debug
information for arrays. The symptom is that when GDB is asked to print an
array-type variable that was compiled with GCC, it shows the array and it's
contents, while when asked to print the same variable for the same program,
compiled by LLVM, all you get is a pointer:
GCC version:
(gdb) print vla
$1 = {5, 7, 9}
(gdb) print vlaref
$2 = (int (&)[3]) @0x7fffffffdc30: {5, 7, 9}
(gdb) print vlaref2
$3 = (const vlareftypedef) @0x7fffffffdc30: {5, 7, 9}
LLVM version:
(gdb) print vla
$1 = 0x7fffffffdc20
(gdb) print vlaref
$2 = (int (&)[]) @0x7fffffffdc20: 0x7fffffffdc20
(gdb) print vlaref2
$3 = (vlareftypedef) @0x7fffffffdc20: 0x7fffffffdc20
LLVM can't even tell gdb the length of the array, much less its contents!
In discussing this with Eric Christopher, he said:
A simple testcase is:
int foo(int a) {
int vla[a];
int sum = 0;
for (int i = 0; i < a; ++i)
vla[i] = i;
for (int j = 0; j < a; ++j)
sum += vla[j];
return sum;
}
int main (void) {
return foo(4);
}
What's happening is that we're not adding a DW_AT_upper_bound of type
DW_FORM_expr/exprloc with the upper bound of the array.
--
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
