From a0b71ad6a3f8aeb8b5ea6d112a7afeadc7c004a4 Mon Sep 17 00:00:00 2001 From: Aurelien Jarno Date: Wed, 19 Sep 2012 22:00:22 +0200 Subject: [PATCH] tcg/optimize: prefer the "op a, a, b" form for commutative ops The "op a, a, b" form is better handled on non-RISC host than the "op a, b, a" form, so swap the arguments to this form when possible, and when b is not a constant. This reduces the number of generated instructions by a tiny bit. Reviewed-by: Richard Henderson Signed-off-by: Aurelien Jarno Signed-off-by: Michael Roth --- tcg/optimize.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/tcg/optimize.c b/tcg/optimize.c index abe016a..c8ae50b 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -434,7 +434,10 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr, CASE_OP_32_64(eqv): CASE_OP_32_64(nand): CASE_OP_32_64(nor): - if (temps[args[1]].state == TCG_TEMP_CONST) { + /* Prefer the constant in second argument, and then the form + op a, a, b, which is better handled on non-RISC hosts. */ + if (temps[args[1]].state == TCG_TEMP_CONST || (args[0] == args[2] + && temps[args[2]].state != TCG_TEMP_CONST)) { tmp = args[1]; args[1] = args[2]; args[2] = tmp;