i386: Use SHR to compare with large power-of-two constants [PR94650]

i386: Use SHR to compare with large power-of-two constants [PR94650]

Convert unsigned compares where

	m >= LARGE_POWER_OF_TWO

and LARGE_POWER_OF_TWO represent an immediate where bit 33+ is set to use
a SHR instruction and compare the result to 0.  This avoids loading a
large immediate with MOVABS insn.

        movabsq $1099511627775, %rax
        cmpq    %rax, %rdi
        ja      .L5

gets converted to:

	shrq	$40, %rdi
	jne	.L5

	PR target/94650
	* config/i386/predicates.md (shr_comparison_operator): New predicate.
	* config/i386/i386.md (compare->shr splitter): New splitters.

testsuite/ChangeLog:

	PR target/94650
	* gcc.targeti/i386/pr94650.c: New test.