[Bug target/79044] New: ICE in insn_is_swappable_p, at config/rs6000/rs6000.c:41191

[doko at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79044

            Bug ID: 79044
           Summary: ICE in insn_is_swappable_p, at
                    config/rs6000/rs6000.c:41191
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: doko at gcc dot gnu.org
  Target Milestone: ---

Created attachment 40492
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40492&action=edit
preprocessed source

seen with the trunk 243972, and the gcc-branch, with -O1 and up. error message
in gcc-6 is slightly different.

$ cat THVectorDispatch.i
float a;
void b() {
  __attribute__((altivec(vector__))) float c = __builtin_vec_xl(0, &a);
  __builtin_vec_xst(c, 0, &a);
}

$ gcc -c -O THVectorDispatch.i 
THVectorDispatch.i: In function 'b':
THVectorDispatch.i:5:1: internal compiler error: in insn_is_swappable_p, at
config/rs6000/rs6000.c:41191
 }
 ^
0x10ab6627 insn_is_swappable_p
        ../../src/gcc/config/rs6000/rs6000.c:41191
0x10ab6627 rs6000_analyze_swaps(function*)
        ../../src/gcc/config/rs6000/rs6000.c:42267
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.

gcc configured with --enable-secureplt --with-cpu=power8


$ gcc-6 -c -O THVectorDispatch.i 
THVectorDispatch.i: In function 'b':
THVectorDispatch.i:5:1: error: unrecognizable insn:
 }
 ^
(insn 6 5 7 2 (set (reg:V4SF 156)
        (vec_select:V4SF (vec_select:V4SF (mem:V4SF (reg/f:DI 157) [0  S16 A8])
                (parallel [
                        (const_int 3 [0x3])
                        (const_int 2 [0x2])
                        (const_int 1 [0x1])
                        (const_int 0 [0])
                    ]))
            (parallel:V4SF [
                    (const_int 2 [0x2])
                    (const_int 3 [0x3])
                    (const_int 0 [0])
                    (const_int 1 [0x1])
                ]))) THVectorDispatch.i:3 -1
     (nil))
THVectorDispatch.i:5:1: internal compiler error: in extract_insn, at
recog.c:2287
Please submit a full bug report,
with preprocessed source if appropriate.