re PR rtl-optimization/68920 (Undesirable if-conversion for a rarely taken branch)

re PR rtl-optimization/68920 (Undesirable if-conversion for a rarely taken branch)

gcc/

2016-01-11  Yuri Rumyantsev  <ysrumyan@gmail.com>

	PR rtl-optimization/68920
	* config/i386/i386.c (ix86_option_override_internal): Restrict number
	of conditional moves for  RTL if-conversion to 1 for
	TARGET_ONE_IF_CONV_INSN.
	* config/i386/i386.h (TARGET_ONE_IF_CONV_INSN): New macros.
	* config/i386/x86-tune.def (X86_TUNE_ONE_IF_CONV_INSN): New macros.
	* params.def (PARAM_MAX_RTL_IF_CONVERSION_INSNS) : Introduce new
	parameter to restirct number of conditional moves for
	RTL if-conversion.
	* doc/invoke.texi (max-rtl-if-conversion-insns): Document it.
	* ifcvt.c (bb_ok_for_noce_convert_multiple_sets): Limit number of
	conditionl moves.

gcc/testsuite/

2016-01-11  Yuri Rumyantsev  <ysrumyan@gmail.com>

	PR rtl-optimization/68920
	* gcc.dg/ifcvt-4.c: Add "--param max-rtl-if-conversion-insns=3" option
	for ix86 targets.
	* gcc.dg/ifcvt-5.c: New test.

From-SVN: r232220