[Bug target/96587] New: [11 Regression] ICE: in extract_constrain_insn, at recog.c:2195 (insn does not satisfy its constraints) with -O2 -fno-dce -fno-tree-forwprop

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96587

            Bug ID: 96587
           Summary: [11 Regression] ICE: in extract_constrain_insn, at
                    recog.c:2195 (insn does not satisfy its constraints)
                    with -O2 -fno-dce -fno-tree-forwprop
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu

Created attachment 49048
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49048&action=edit
reduced testcase

Compiler output:
$ x86_64-pc-linux-gnu-gcc -O2 -fno-dce -fno-tree-forwprop testcase.c 
testcase.c: In function 'foo':
testcase.c:9:1: error: insn does not satisfy its constraints:
    9 | }
      | ^
(insn 94 14 95 2 (parallel [
            (set (reg:SI 20 xmm0 [97])
                (const_int 0 [0]))
            (clobber (reg:CC 17 flags))
        ]) "testcase.c":7:39 67 {*movsi_xor}
     (expr_list:REG_UNUSED (reg:CC 17 flags)
        (nil)))
during RTL pass: cprop_hardreg
testcase.c:9:1: internal compiler error: in extract_constrain_insn, at
recog.c:2195
0x6dab93 _fatal_insn(char const*, rtx_def const*, char const*, int, char
const*)
        /repo/gcc-trunk/gcc/rtl-error.c:108
0x6dac20 _fatal_insn_not_found(rtx_def const*, char const*, int, char const*)
        /repo/gcc-trunk/gcc/rtl-error.c:118
0x6c9f27 extract_constrain_insn(rtx_insn*)
        /repo/gcc-trunk/gcc/recog.c:2195
0xf2c81c copyprop_hardreg_forward_1
        /repo/gcc-trunk/gcc/regcprop.c:802
0xf2daae execute
        /repo/gcc-trunk/gcc/regcprop.c:1367
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-amd64/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r11-2662-20200812081137-g220ffae474d-checking-yes-rtl-df-extra-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/11.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--with-cloog --with-ppl --with-isl --build=x86_64-pc-linux-gnu
--host=x86_64-pc-linux-gnu --target=x86_64-pc-linux-gnu
--with-ld=/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=/usr/bin/x86_64-pc-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r11-2662-20200812081137-g220ffae474d-checking-yes-rtl-df-extra-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.0.0 20200812 (experimental) (GCC)