Fix issue with x86_64_const_vector_operand predicate on x86.
This patch fixes (what I believe is) a latent bug in i386.md's
x86_64_const_vector_operand define_predicate. According to the
documentation, when a predicate is called with rtx operand OP and
machine_mode operand MODE, we can't shouldn't assume that the
MODE is (or has been checked to be) GET_MODE (OP).
The failure mode is that recog can call x86_64_const_vector_operand
on an arbitrary CONST_VECTOR passing a MODE of V2QI_mode, but when
the CONST_VECTOR is in fact V1TImode, it's unsafe to directly call
ix86_convert_const_vector_to_integer, which assumes that the CONST_VECTOR
contains CONST_INTs when it actually contains CONST_WIDE_INTs. The
checks in this define_predicate need to be testing OP's mode, and
ideally confirming that this matches the passed in/specified MODE.
This bug is currently latent, but adding an innocent/unrelated
define_insn, such as "(set (reg:CCC FLAGS_REG) (const_int 0))" to
i386.md can occasionally change the order in which genrecog generates
its tests, then ICEing during bootstrap due to V1TI CONST_VECTORs.
2022-07-18 Roger Sayle <roger@nextmovesoftware.com>
gcc/ChangeLog
* config/i386/predicates.md (x86_64_const_vector_operand):
Check the operand's mode matches the specified mode argument.