On Tue, Feb 19, 2013 at 7:03 PM, Richard Henderson <r...@twiddle.net> wrote:
> Signed-off-by: Richard Henderson <r...@twiddle.net>
> ---
> tcg/optimize.c | 33 ++++++++++++++++++++++++++++++++-
> 1 file changed, 32 insertions(+), 1 deletion(-)
>
> I noticed this while looking at other dumps. This seems like it
> should be considered independently of the other patch series.
This breaks Sparc32 boot, only a few first instructions are executed.
>
> r~
>
>
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index 973d2d6..7c172c5 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -575,7 +575,8 @@ 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):
> @@ -591,6 +592,36 @@ 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;
> + gen_args[0] = args[0];
> + gen_args[1] = args[2];
> + args += 3;
> + gen_args += 2;
> + continue;
> + }
> + }
> + break;
> default:
> break;
> }
> --
> 1.8.1.2
>
