[Bug tree-optimization/71830] New: gcc ICE at -O3 on valid code on x86_64-linux-gnu: verify_gimple failed

[helloqirun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71830

            Bug ID: 71830
           Summary: gcc ICE at -O3 on valid code on x86_64-linux-gnu:
                    verify_gimple failed
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: helloqirun at gmail dot com
  Target Milestone: ---

The following valid code causes an ICE when compiled with the current gcc trunk
at only -O3 on x86_64-linux-gnu in only 32-bit mode.


It appears to be a 7 regression.


$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/home/absozero/trunk/root-gcc/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --prefix=/home/absozero/trunk/root-gcc
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 7.0.0 20160710 (experimental) [trunk revision 238196] (GCC)


$ gcc-trunk -O3 -c abc.c
$ gcc-trunk -O3 -m32 abc.c
abc.c: In function ‘fn1’:
abc.c:7:6: error: non-trivial conversion at assignment
 void fn1() {
      ^~~
int
struct S0
# VUSE <.MEM_5(D)>
pretmp_4 = b;
abc.c:7:6: internal compiler error: verify_gimple failed
0xbb5e35 verify_gimple_in_cfg(function*, bool)
        ../../gcc/gcc/tree-cfg.c:5212
0xaa1cc3 execute_function_todo
        ../../gcc/gcc/passes.c:1964
0xaa2d0b execute_todo
        ../../gcc/gcc/passes.c:2016
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.




$ cat abc.c
#pragma pack(1)
struct S0 {
  int f0;
};
char a, d;
static struct S0 b, c;
void fn1() {
  for (;;) {
    struct S0 e = b;
    c = b;
    d = e.f0;
    for (; a;)
      b = c;
  }
}