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[Patch 3/2 ifcvt costs] Don't expand a conditional move between identical sources

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gcc/

	* optabs.c (emit_condiitonal_move): Short circuit for identical
	sources.

From-SVN: r238595
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James Greenhalgh 2016-07-21 15:41:59 +00:00 • committed by James Greenhalgh
parent ebe8f3226c
commit f5a459a439
2 changed files with 16 additions and 0 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2016-07-21 James Greenhalgh <james.greenhalgh@arm.com>
* optabs.c (emit_condiitonal_move): Short circuit for identical
sources.
2016-07-21 James Greenhalgh <james.greenhalgh@arm.com>
* ifcvt.c (noce_if_info): New fields: speed_p, original_cost,

11
gcc/optabs.c
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@ -4214,6 +4214,17 @@ emit_conditional_move (rtx target, enum rtx_code code, rtx op0, rtx op1,
enum insn_code icode;
enum rtx_code reversed;
/* If the two source operands are identical, that's just a move. */
if (rtx_equal_p (op2, op3))
{
if (!target)
target = gen_reg_rtx (mode);
emit_move_insn (target, op3);
return target;
}
/* If one operand is constant, make it the second one. Only do this
if the other operand is not constant as well. */