PR middle-end/84309
	* match.pd (pow(C,x) -> exp(log(C)*x)): Optimize instead into
	exp2(log2(C)*x) if C is a power of 2 and c99 runtime is available.
	* generic-match-head.c (canonicalize_math_after_vectorization_p): New
	inline function.
	* gimple-match-head.c (canonicalize_math_after_vectorization_p): New
	inline function.
	* omp-simd-clone.h: New file.
	* omp-simd-clone.c: Include omp-simd-clone.h.
	(expand_simd_clones): No longer static.
	* tree-vect-patterns.c: Include fold-const-call.h, attribs.h,
	cgraph.h and omp-simd-clone.h.
	(vect_recog_pow_pattern): Optimize pow(C,x) to exp(log(C)*x).
	(vect_recog_widen_shift_pattern): Formatting fix.
	(vect_pattern_recog_1): Don't check optab for calls.

	* gcc.dg/pr84309.c: New test.
	* gcc.target/i386/pr84309.c: New test.

From-SVN: r257617