https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112494
Bug ID: 112494
Summary: GCC: 14: internal compiler error: in ix86_cc_mode, at
config/i386/i386.cc:16477
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: 141242068 at smail dot nju.edu.cn
Target Milestone: ---
Compiler Explorer: https://gcc.godbolt.org/z/cPPxenx7q
When compile this program with `-Og -fno-tree-copy-prop -fno-tree-fre
-fno-tree-ccp -fno-tree-forwprop`, gcc crashes:
```
#include <x86intrin.h>
#ifdef __x86_64__
# define EFLAGS_TYPE unsigned long long int
#else
# define EFLAGS_TYPE unsigned int
#endif
int main() {
EFLAGS_TYPE flags = 0xD7;
__writeeflags(0xD7);
flags && !__readeflags();
if ((flags && (!__readeflags())) != 0xD7);
return 0;
}
```
There are some intriguing observations about this crash.
1. Removing the `flags &&` portion at the point of the first __readeflags()
call eliminates the crash, even though it appears that `flags &&` has no
effect.
2. Removing the `!= 0xD7` portion at the point of the second __readeflags()
call also eliminates the crash.
The crash output:
```
during RTL pass: combine
<source>: In function 'main':
<source>:15:1: internal compiler error: in ix86_cc_mode, at
config/i386/i386.cc:16477
15 | }
| ^
0x238b15e internal_error(char const*, ...)
???:0
0xa11270 fancy_abort(char const*, int, char const*)
???:0
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Compiler returned: 1
```
