Commit 3031244b authored by Aurelien Jarno's avatar Aurelien Jarno Committed by Richard Henderson
Browse files

tcg/optimize: fix known-zero bits optimization 



Known-zero bits optimization is a great idea that helps to generate more
optimized code. However the current implementation only works in very few
cases as the computed mask is not saved.

Fix this to make it really working.

Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: default avatarRichard Henderson <rth@twiddle.net>
parent e46b225a

tcg/optimize.c

+7 −1
Original line number Diff line number Diff line
@@ -691,7 +691,8 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr, 
            break;

        }



        /* Simplify using known-zero bits */

        /* Simplify using known-zero bits. Currently only ops with a single

           output argument is supported. */

        mask = -1;

        affected = -1;

        switch (op) {
@@ -1149,6 +1150,11 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr, 
            } else {

                for (i = 0; i < def->nb_oargs; i++) {

                    reset_temp(args[i]);

                    /* Save the corresponding known-zero bits mask for the

                       first output argument (only one supported so far). */

                    if (i == 0) {

                        temps[args[i]].mask = mask;

                    }

                }

            }

            for (i = 0; i < def->nb_args; i++) {