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tcg/optimize: Add more identity simplifications 

Recognize 0 operand to andc, and -1 operands to and, orc, eqv.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2014-01-31 07:42:11 -06:00
parent e64e958e20
commit 464a1441c1
1 changed files with 24 additions and 15 deletions
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39
tcg/optimize.c
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@ -716,7 +716,7 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
break;
}
/* Simplify expression for "op r, a, 0 => mov r, a" cases */
/* Simplify expression for "op r, a, const => mov r, a" cases */
switch (op) {
CASE_OP_32_64(add):
CASE_OP_32_64(sub):
@ -727,23 +727,32 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
CASE_OP_32_64(rotr):
CASE_OP_32_64(or):
CASE_OP_32_64(xor):
if (temps[args[1]].state == TCG_TEMP_CONST) {
/* Proceed with possible constant folding. */
break;
}
if (temps[args[2]].state == TCG_TEMP_CONST
CASE_OP_32_64(andc):
if (temps[args[1]].state != TCG_TEMP_CONST
&& temps[args[2]].state == TCG_TEMP_CONST
&& temps[args[2]].val == 0) {
if (temps_are_copies(args[0], args[1])) {
s->gen_opc_buf[op_index] = INDEX_op_nop;
} else {
s->gen_opc_buf[op_index] = op_to_mov(op);
tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
gen_args += 2;
}
args += 3;
continue;
goto do_mov3;
}
break;
CASE_OP_32_64(and):
CASE_OP_32_64(orc):
CASE_OP_32_64(eqv):
if (temps[args[1]].state != TCG_TEMP_CONST
&& temps[args[2]].state == TCG_TEMP_CONST
&& temps[args[2]].val == -1) {
goto do_mov3;
}
break;
do_mov3:
if (temps_are_copies(args[0], args[1])) {
s->gen_opc_buf[op_index] = INDEX_op_nop;
} else {
s->gen_opc_buf[op_index] = op_to_mov(op);
tcg_opt_gen_mov(s, gen_args, args[0], args[1]);
gen_args += 2;
}
args += 3;
continue;
default:
break;
}