[Bug tree-optimization/105394] New: [12 Regression] ICE: verify_gimple failed with MVE during GIMPLE pass: veclower2

["acoplan at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105394

            Bug ID: 105394
           Summary: [12 Regression] ICE: verify_gimple failed with MVE
                    during GIMPLE pass: veclower2
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: acoplan at gcc dot gnu.org
  Target Milestone: ---

The following fails:

$ ./arm-eabi-gcc -c ~/toolchain/src/gcc/gcc/testsuite/g++.dg/opt/pr79734.C
-march=armv8.1-m.main+mve -mfloat-abi=hard -O
/home/alecop01/toolchain/src/gcc/gcc/testsuite/g++.dg/opt/pr79734.C: In
function 'void foo(V*, V*)':
/home/alecop01/toolchain/src/gcc/gcc/testsuite/g++.dg/opt/pr79734.C:9:1: error:
integral result type precision does not match field size of 'bit_field_ref'
    9 | foo (V *a, V *b)
      | ^~~
_40 = BIT_FIELD_REF <_6, 32, 0>;
/home/alecop01/toolchain/src/gcc/gcc/testsuite/g++.dg/opt/pr79734.C:9:1: error:
integral result type precision does not match field size of 'bit_field_ref'
_42 = BIT_FIELD_REF <_6, 32, 32>;
/home/alecop01/toolchain/src/gcc/gcc/testsuite/g++.dg/opt/pr79734.C:9:1: error:
integral result type precision does not match field size of 'bit_field_ref'
_44 = BIT_FIELD_REF <_6, 32, 64>;
/home/alecop01/toolchain/src/gcc/gcc/testsuite/g++.dg/opt/pr79734.C:9:1: error:
integral result type precision does not match field size of 'bit_field_ref'
_46 = BIT_FIELD_REF <_6, 32, 96>;
during GIMPLE pass: veclower2
/home/alecop01/toolchain/src/gcc/gcc/testsuite/g++.dg/opt/pr79734.C:9:1:
internal compiler error: verify_gimple failed
0x110c388 verify_gimple_in_cfg(function*, bool)
        /home/alecop01/toolchain/src/gcc/gcc/tree-cfg.cc:5561
0xfa3726 execute_function_todo
        /home/alecop01/toolchain/src/gcc/gcc/passes.cc:2085
0xfa388e do_per_function
        /home/alecop01/toolchain/src/gcc/gcc/passes.cc:1688
0xfa3a29 execute_todo
        /home/alecop01/toolchain/src/gcc/gcc/passes.cc:2139
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.

Since commit r12-7339-g91224cf625dc90304bb515a0cc602beed48fe3da, the arm build
was broken. Commit r12-7356-gfd0ab7c734b04b91653467b94afd48ceca122083 fixes the
build, and we start seeing the ICE after this commit. So the triggering commit
is in this range.