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authorRichard Henderson <rth@twiddle.net>2013-03-21 09:13:33 -0700
committerBlue Swirl <blauwirbel@gmail.com>2013-03-23 14:31:03 +0000
commit2d497542e1ee66598be8bb7ce6a4606d664417ac (patch)
tree34b03a69ce3c8f2a9779f96d798d5bcd63a2901a /tcg
parent4980ef9e3e12be3b4ef9092abc2d5a665199b422 (diff)
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tcg-optimize: Fold sub r,0,x to neg r,x
Cc: Blue Swirl <blauwirbel@gmail.com> Signed-off-by: Richard Henderson <rth@twiddle.net> Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Diffstat (limited to 'tcg')
-rw-r--r--tcg/optimize.c34
1 files changed, 33 insertions, 1 deletions
diff --git a/tcg/optimize.c b/tcg/optimize.c
index bc6e5c1..1b6644c 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -576,7 +576,8 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
break;
}
- /* Simplify expressions for "shift/rot r, 0, a => movi r, 0" */
+ /* Simplify expressions for "shift/rot r, 0, a => movi r, 0",
+ and "sub r, 0, a => neg r, a" case. */
switch (op) {
CASE_OP_32_64(shl):
CASE_OP_32_64(shr):
@@ -592,6 +593,37 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
continue;
}
break;
+ CASE_OP_32_64(sub):
+ {
+ TCGOpcode neg_op;
+ bool have_neg;
+
+ if (temps[args[2]].state == TCG_TEMP_CONST) {
+ /* Proceed with possible constant folding. */
+ break;
+ }
+ if (op == INDEX_op_sub_i32) {
+ neg_op = INDEX_op_neg_i32;
+ have_neg = TCG_TARGET_HAS_neg_i32;
+ } else {
+ neg_op = INDEX_op_neg_i64;
+ have_neg = TCG_TARGET_HAS_neg_i64;
+ }
+ if (!have_neg) {
+ break;
+ }
+ if (temps[args[1]].state == TCG_TEMP_CONST
+ && temps[args[1]].val == 0) {
+ s->gen_opc_buf[op_index] = neg_op;
+ reset_temp(args[0]);
+ gen_args[0] = args[0];
+ gen_args[1] = args[2];
+ args += 3;
+ gen_args += 2;
+ continue;
+ }
+ }
+ break;
default:
break;
}