re PR target/77452 (ICE: in plus_constant, at explow.c:87 with -fno-split-wide-types -mavx512f --param=max-combine-insns=2)

	PR rtl-optimization/77452
	* explow.c (plus_constant) <case MEM>: Extract scalar constant from
	inner-mode reference to a CONST_VECTOR constant in the constant pool.

testsuite/ChangeLog:

	PR rtl-optimization/77452
	* gcc.target/i386/pr77452.c: New test.

From-SVN: r239989