I found a potential issue with vstring usage in r_assemble_list() in
cgemit.cxx.
The opnd[] and result[] are storing addresses off a vstring 'buf' while
it is being appended. If one of the 'append' triggers a realloc and new
block has to be alloc'ed, the old pointers in opnd[] and result[] become
stale. This can lead to garbage printed in the output asm files.
Below is one possible way to fix it by storing the offsets instead of
addresses while 'buf' is growing.
Our code has diverged from open64 so much, I do not have an environment
setup to build/test the trunk. I merely point it out since it could bite
someone later. If this needs to be fixed, we need an volunteer to pick
it up and review/test the change and submit it.
Regards,
Ding-Kai
Index: cgemit.cxx
===================================================================
--- cgemit.cxx (revision 3360)
+++ cgemit.cxx (working copy)
@@ -1778,10 +1778,13 @@
{
#ifdef TARG_X8664
const char *result[ISA_OPERAND_max_results+1];
+ UINT result_str_offset[ISA_OPERAND_max_results+1];
#else
const char *result[ISA_OPERAND_max_results];
+ UINT result_str_offset[ISA_OPERAND_max_results];
#endif
const char *opnd[ISA_OPERAND_max_operands];
+ UINT opnd_str_offset[ISA_OPERAND_max_results];
vstring buf = vstr_begin(LBUF_LEN);
INT i;
INT lc = 0;
@@ -1838,7 +1841,7 @@
}
// need end-of-string between each operand
buf = vstr_append(buf, '\0');
- opnd[i] = vstr_str(buf)+start;
+ opnd_str_offset[i] = start;
}
for (i = 0; i < OP_results(op); i++) {
@@ -1871,9 +1874,16 @@
}
buf = vstr_concat(buf, rname);
buf = vstr_append(buf, '\0'); // increment vstr length
- result[i] = vstr_str(buf)+start;
+ result_str_offset[i] = start;
}
+ const char* vstr_buf = vstr_str(buf);
+ for (i = 0; i < OP_opnds(op); i++) {
+ opnd[i] = opnd_str_offset[i]+vstr_buf;
+ }
+ for (i = 0; i < OP_results(op); i++) {
+ result[i] = result_str_offset[i]+vstr_buf;
+ }
fputc ('\t', Asm_File);
#ifdef TARG_X8664
lc = CGEMIT_Print_Inst( op, result, opnd, Asm_File );
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