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tcg: Optimize two-address commutative operations

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While swapping constants to the second operand, swap
sources matching destinations to the first operand.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This commit is contained in:
Richard Henderson 2012-09-21 10:13:38 -07:00 committed by Aurelien Jarno
parent fa01a2084e
commit 5d8f536300
1 changed files with 14 additions and 1 deletions
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15
tcg/optimize.c
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@ -334,6 +334,8 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
const TCGOpDef *def;
TCGArg *gen_args;
TCGArg tmp;
TCGCond cond;
/* Array VALS has an element for each temp.
If this temp holds a constant then its value is kept in VALS' element.
If this temp is a copy of other ones then this equivalence class'
@ -395,13 +397,24 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
}
break;
CASE_OP_32_64(movcond):
cond = args[5];
if (temps[args[1]].state == TCG_TEMP_CONST
&& temps[args[2]].state != TCG_TEMP_CONST) {
tmp = args[1];
args[1] = args[2];
args[2] = tmp;
args[5] = tcg_swap_cond(args[5]);
cond = tcg_swap_cond(cond);
}
/* For movcond, we canonicalize the "false" input reg to match
the destination reg so that the tcg backend can implement
a "move if true" operation. */
if (args[0] == args[3]) {
tmp = args[3];
args[3] = args[4];
args[4] = tmp;
cond = tcg_invert_cond(cond);
}
args[5] = cond;
default:
break;
}