https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123448
Bug ID: 123448
Summary: ICE: in extract_constrain_insn, at recog.cc during
LRA/reload with conflicting "0a" constraint and
clobber
Product: gcc
Version: 15.2.0
Status: UNCONFIRMED
Keywords: inline-asm
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: 522024330006 at smail dot nju.edu.cn
Target Milestone: ---
Reproducer: https://godbolt.org/z/9TzYezcsc
The crash occurs during the reload (LRA) pass. It appears to be caused by a
combination of:
A matching constraint "0" coupled with a specific register constraint "a".
The specific register (eax/rax) being listed in the clobber list.
This creates an unsatisfiable set of constraints for the register allocator,
leading to an "unrecognizable insn".
```C
#include <stdint.h>
int main() {
uint32_t result = 0x1234;
int i;
// crash here
asm volatile("nop"
: "+r"(result), "=m"(i)
: "0a"(&result)
: "eax");
return result;
}
```
Traceback:
```
/workspace/exps/featurefuzz/random_combine_feature_set_3_exp/bugs/16014.fuzz:20:1:
error: unrecognizable insn:
20 | }
| ^
(insn 9 19 10 2 (parallel [
(set (reg:SI 1 dx [102])
(asm_operands/v:SI ("shrl %0; xorl %1,%%eax") ("=r") 0 [
(reg/f:DI 2 cx [103])
(reg:SI 1 dx [102])
]
[
(asm_input:DI ("0a")
/workspace/exps/featurefuzz/random_combine_feature_set_3_exp/bugs/16014.fuzz:14)
(asm_input:SI ("0")
/workspace/exps/featurefuzz/random_combine_feature_set_3_exp/bugs/16014.fuzz:14)
]
[]
/workspace/exps/featurefuzz/random_combine_feature_set_3_exp/bugs/16014.fuzz:14))
(set (mem/c:SI (plus:DI (reg/f:DI 7 sp)
(const_int -4 [0xfffffffffffffffc])) [1 i+0 S4 A32])
(asm_operands/v:SI ("shrl %0; xorl %1,%%eax") ("=m") 1 [
(reg/f:DI 2 cx [103])
(reg:SI 1 dx [102])
]
[
(asm_input:DI ("0a")
/workspace/exps/featurefuzz/random_combine_feature_set_3_exp/bugs/16014.fuzz:14)
(asm_input:SI ("0")
/workspace/exps/featurefuzz/random_combine_feature_set_3_exp/bugs/16014.fuzz:14)
]
[]
/workspace/exps/featurefuzz/random_combine_feature_set_3_exp/bugs/16014.fuzz:14))
(clobber (reg:DI 0 ax))
(clobber (reg:CC 17 flags))
])
"/workspace/exps/featurefuzz/random_combine_feature_set_3_exp/bugs/16014.fuzz":14:5
-1
(nil))
during RTL pass: reload
/workspace/exps/featurefuzz/random_combine_feature_set_3_exp/bugs/16014.fuzz:20:1:
internal compiler error: in extract_constrain_insn, at recog.cc:2783
0x5da1dc8 internal_error(char const*, ...)
/workspace/install/gcc/src/gcc/gcc/diagnostic-global-context.cc:517
0x5d3f858 fancy_abort(char const*, int, char const*)
/workspace/install/gcc/src/gcc/gcc/diagnostic.cc:1749
0x2615285 _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
/workspace/install/gcc/src/gcc/gcc/rtl-error.cc:108
0x26152ee _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
/workspace/install/gcc/src/gcc/gcc/rtl-error.cc:116
0x2578724 extract_constrain_insn(rtx_insn*)
/workspace/install/gcc/src/gcc/gcc/recog.cc:2783
0x22626be check_rtl
/workspace/install/gcc/src/gcc/gcc/lra.cc:2202
0x2263ebb lra(_IO_FILE*, int)
/workspace/install/gcc/src/gcc/gcc/lra.cc:2636
0x21c7d60 do_reload
/workspace/install/gcc/src/gcc/gcc/ira.cc:5987
0x21c883a execute
/workspace/install/gcc/src/gcc/gcc/ira.cc:6175
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.
```
