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(jump_optimize): Use emit_store_flag even if branches are cheap, if

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the store is even cheaper.

From-SVN: r12982
This commit is contained in:
Richard Kenner 1996-10-21 07:39:13 -04:00
parent 1cd4bca92c
commit 04d23d7c9f
1 changed files with 17 additions and 10 deletions

27
gcc/jump.c

@ -1,5 +1,5 @@
/* Optimize jump instructions, for GNU compiler.
Copyright (C) 1987, 88, 89, 91-95, 1996 Free Software Foundation, Inc.b
Copyright (C) 1987, 88, 89, 91-95, 1996 Free Software Foundation, Inc.
This file is part of GNU CC.
@ -1165,13 +1165,9 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
We could handle BLKmode if (1) emit_store_flag could
and (2) we could find the size reliably. */
&& GET_MODE (XEXP (temp4, 0)) != BLKmode
/* No point in doing any of this if branches are cheap or we
don't have conditional moves. */
&& (BRANCH_COST >= 2
#ifdef HAVE_conditional_move
|| 1
#endif
)
/* Even if branches are cheap, the store_flag optimization
can win when the operation to be performed can be
expressed directly. */
#ifdef HAVE_cc0
/* If the previous insn sets CC0 and something else, we can't
do this since we are going to delete that insn. */
@ -1282,8 +1278,19 @@ jump_optimize (f, cross_jump, noop_moves, after_regscan)
can reverse the condition. See if (3) applies possibly
by reversing the condition. Prefer reversing to (4) when
branches are very expensive. */
&& ((reversep = 0, temp2 == const0_rtx)
|| (temp3 == const0_rtx
&& (((BRANCH_COST >= 2
|| STORE_FLAG_VALUE == -1
|| (STORE_FLAG_VALUE == 1
/* Check that the mask is a power of two,
so that it can probably be generated
with a shift. */
&& exact_log2 (INTVAL (temp3)) >= 0))
&& (reversep = 0, temp2 == const0_rtx))
|| ((BRANCH_COST >= 2
|| STORE_FLAG_VALUE == -1
|| (STORE_FLAG_VALUE == 1
&& exact_log2 (INTVAL (temp2)) >= 0))
&& temp3 == const0_rtx
&& (reversep = can_reverse_comparison_p (temp4, insn)))
|| (BRANCH_COST >= 2
&& GET_CODE (temp2) == CONST_INT