[PATCH 3/4] Set costs for jumps in combine

[Bernd Schmidt]

The combiner is somewhat strange about how it uses costs. If any of the
insns involved in a comparison have a cost of 0, it does not verify that
the substitution is cheaper. Also, it does not compute costs for jump
insns, so they are always set to zero. As a consequence, any possible
substitution is performed if a combination into a jump is possible,
which turns out isn't really desirable on m68k with cbranch patterns.

This patch simply removes a test for NONJUMP_INSN_P. Bootstrapped and
tested on the gcc135 machine (powerpc64le-unknown-linux-gnu).


Bernd

	* combine.c (combine_instructions): Record costs for jumps.

diff --git a/gcc/combine.c b/gcc/combine.c
index 857ea30dafd..9446d2769ab 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -1234,8 +1234,7 @@ combine_instructions (rtx_insn *f, unsigned int nregs)
 						    insn);
 
 	    /* Record the current insn_cost of this instruction.  */
-	    if (NONJUMP_INSN_P (insn))
-	      INSN_COST (insn) = insn_cost (insn, optimize_this_for_speed_p);
+	    INSN_COST (insn) = insn_cost (insn, optimize_this_for_speed_p);
 	    if (dump_file)
 	      {
 		fprintf (dump_file, "insn_cost %d for ", INSN_COST (insn));