[Bug tree-optimization/70152] New: gcc ICE at -O3 and above on valid code on x86_64-linux-gnu in "replace_uses_by"

[helloqirun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70152

            Bug ID: 70152
           Summary: gcc ICE at -O3 and above on valid code on
                    x86_64-linux-gnu in "replace_uses_by"
           Product: gcc
           Version: 6.0
            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 -O3 and above on x86_64-linux-gnu in both 32-bit and 64-bit modes.

It should be a 6 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/6.0.0/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 6.0.0 20160308 (experimental) [trunk revision 234065] (GCC)



$ gcc-trunk -O3 abc.c
abc.c: In function 'zfgetline.isra.0':
abc.c:17:1: internal compiler error: in replace_uses_by, at tree-cfg.c:1825
 }
 ^
0xb96859 replace_uses_by(tree_node*, tree_node*)
        ../../gcc/gcc/tree-cfg.c:1825
0xc3a82e replace_removed_params_ssa_names
        ../../gcc/gcc/tree-sra.c:4771
0xc3cdce ipa_sra_modify_function_body(vec<ipa_parm_adjustment, va_heap,
vl_ptr>)
        ../../gcc/gcc/tree-sra.c:4854
0xc3d5d1 modify_function
        ../../gcc/gcc/tree-sra.c:5173
0xc477b6 ipa_early_sra
        ../../gcc/gcc/tree-sra.c:5403
0xc477b6 execute
        ../../gcc/gcc/tree-sra.c:5450
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
int a;
int fgetc ();
void _setjmp ();
static int zfgetline (int p1)
{
  p1 = 0;
  _setjmp ();
  for (;;)
    switch (p1)
      case 5:
      p1 = fgetc ();
}

void zftp_login ()
{
  zfgetline (a);
}