x86: PR target/103773: Fix wrong-code with -Oz from pop to memory.

x86: PR target/103773: Fix wrong-code with -Oz from pop to memory.

This is a fix to PR target/103773 where -Oz shouldn't use push/pop
on x86 to shrink writing small integer constants to memory.
Instead clang uses "andl $0, mem" for writing zero, and "orl $-1, mem"
when writing -1 to memory when using -Oz.  This patch implements this
via peephole2 where we can confirm that its ok to clobber the flags.

2021-12-23  Roger Sayle  <roger@nextmovesoftware.com>
	    Uroš Bizjak  <ubizjak@gmail.com>

gcc/ChangeLog
	PR target/103773
	* config/i386/i386.md (*mov<mode>_and): New define_insn for
	writing a zero to memory using AND.
	(*mov<mode>_or): Extend to allow memory destination and HImode.
	(*movdi_internal): Remove -Oz push/pop optimization from here.
	(*movsi_internal): Likewise.
	(peephole2): Perform -Oz push/pop optimization here, only for
	register destinations, values other than zero, and in functions
	that don't used the red zone.
	(peephole2): With -Oz, convert writes of 0 or -1 to memory into
	their clobber forms, i.e. *mov<mode>_and and *mov<mode>_or resp.

gcc/testsuite/ChangeLog
	PR target/103773
	* gcc.target/i386/pr103773-2.c: New test case.
	* gcc.target/i386/pr103773.c: New test case.