This patch resolves PR target/106450, some more fall-out from more
aggressive TImode scalar-to-vector (STV) optimizations.  I continue
to be caught out by how far TImode STV has diverged from DImode/SImode
STV, and therefore requires additional (unexpected) tweaking.  Many
thanks to H.J. Lu for pointing out timode_remove_non_convertible_regs
needs to be extended to handle XOR (and other new operations).

Unhelpfully the comment above this function states that it's the TImode
version of "remove_non_convertible_regs", which doesn't exist anymore,
so I've resurrected an explanatory comment from the git history.
By refactoring the checks for hard regs and already "marked" regs
into timode_check_non_convertible_regs itself, all its callers are
simplified.  This patch then uses GET_RTX_CLASS to generically handle
unary and binary operations, calling timode_check_non_convertible_regs
on each TImode register operand in the single_set's SET_SRC.

This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
and make -k check, both with and without --target_board=unix{-m32},
with no new failures.  Ok for mainline?


2022-07-28  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
        PR target/106450
        * config/i386/i386-features.cc (timode_check_non_convertible_regs):
        Do nothing if REGNO is set in the REGS bitmap, or is a hard reg.
        (timode_remove_non_convertible_regs): Update comment.
        Call timode_check_non_convertible_regs on all register operands
        of supported (binary and unary) operations.

gcc/testsuite/ChangeLog
        PR target/106450
        * gcc.target/i386/pr106450.c: New test case.


Thanks in advance,
Roger
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