| Message ID | 20241220041104.53105-3-richard.henderson@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | tcg: Remove in-flight mask data from OptContext | expand |
On 12/19/24 20:10, Richard Henderson wrote: > There are only a few logical operations which can compute > an "affected" mask. Split out handling of this optimization > to a separate function, only to be called when applicable. > > Remove the a_mask field from OptContext, as the mask is > no longer stored anywhere. > > Signed-off-by: Richard Henderson <richard.henderson@linaro.org> > --- > tcg/optimize.c | 42 +++++++++++++++++++++++++++--------------- > 1 file changed, 27 insertions(+), 15 deletions(-) > > diff --git a/tcg/optimize.c b/tcg/optimize.c > index 453e8c43bd..6757fe0036 100644 > --- a/tcg/optimize.c > +++ b/tcg/optimize.c > @@ -64,7 +64,6 @@ typedef struct OptContext { > QSIMPLEQ_HEAD(, MemCopyInfo) mem_free; > > /* In flight values from optimization. */ > - uint64_t a_mask; /* mask bit is 0 iff value identical to first input */ > uint64_t z_mask; /* mask bit is 0 iff value bit is 0 */ > uint64_t s_mask; /* mask of clrsb(value) bits */ > TCGType type; > @@ -1047,7 +1046,6 @@ static bool fold_const2_commutative(OptContext *ctx, TCGOp *op) > > static bool fold_masks(OptContext *ctx, TCGOp *op) > { > - uint64_t a_mask = ctx->a_mask; > uint64_t z_mask = ctx->z_mask; > uint64_t s_mask = ctx->s_mask; > > @@ -1059,7 +1057,6 @@ static bool fold_masks(OptContext *ctx, TCGOp *op) > * type changing opcodes. > */ > if (ctx->type == TCG_TYPE_I32) { > - a_mask = (int32_t)a_mask; > z_mask = (int32_t)z_mask; > s_mask |= MAKE_64BIT_MASK(32, 32); > ctx->z_mask = z_mask; > @@ -1069,6 +1066,19 @@ static bool fold_masks(OptContext *ctx, TCGOp *op) > if (z_mask == 0) { > return tcg_opt_gen_movi(ctx, op, op->args[0], 0); > } > + return false; > +} > + > +/* > + * An "affected" mask bit is 0 if and only if the result is identical > + * to the first input. Thus if the entire mask is 0, the operation > + * is equivalent to a copy. > + */ > +static bool fold_affected_mask(OptContext *ctx, TCGOp *op, uint64_t a_mask) > +{ > + if (ctx->type == TCG_TYPE_I32) { > + a_mask = (uint32_t)a_mask; > + } > if (a_mask == 0) { > return tcg_opt_gen_mov(ctx, op, op->args[0], op->args[1]); > } > @@ -1305,8 +1315,9 @@ static bool fold_and(OptContext *ctx, TCGOp *op) > * Known-zeros does not imply known-ones. Therefore unless > * arg2 is constant, we can't infer affected bits from it. > */ > - if (arg_is_const(op->args[2])) { > - ctx->a_mask = z1 & ~z2; > + if (arg_is_const(op->args[2]) && > + fold_affected_mask(ctx, op, z1 & ~z2)) { > + return true; > } > > return fold_masks(ctx, op); > @@ -1331,7 +1342,9 @@ static bool fold_andc(OptContext *ctx, TCGOp *op) > */ > if (arg_is_const(op->args[2])) { > uint64_t z2 = ~arg_info(op->args[2])->z_mask; > - ctx->a_mask = z1 & ~z2; > + if (fold_affected_mask(ctx, op, z1 & ~z2)) { > + return true; > + } > z1 &= z2; > } > ctx->z_mask = z1; > @@ -1709,8 +1722,8 @@ static bool fold_extract(OptContext *ctx, TCGOp *op) > > z_mask_old = arg_info(op->args[1])->z_mask; > z_mask = extract64(z_mask_old, pos, len); > - if (pos == 0) { > - ctx->a_mask = z_mask_old ^ z_mask; > + if (pos == 0 && fold_affected_mask(ctx, op, z_mask_old ^ z_mask)) { > + return true; > } > ctx->z_mask = z_mask; > ctx->s_mask = smask_from_zmask(z_mask); > @@ -1777,8 +1790,8 @@ static bool fold_exts(OptContext *ctx, TCGOp *op) > > ctx->z_mask = z_mask; > ctx->s_mask = s_mask; > - if (!type_change) { > - ctx->a_mask = s_mask & ~s_mask_old; > + if (!type_change && fold_affected_mask(ctx, op, s_mask & ~s_mask_old)) { > + return true; > } > > return fold_masks(ctx, op); > @@ -1819,8 +1832,8 @@ static bool fold_extu(OptContext *ctx, TCGOp *op) > > ctx->z_mask = z_mask; > ctx->s_mask = smask_from_zmask(z_mask); > - if (!type_change) { > - ctx->a_mask = z_mask_old ^ z_mask; > + if (!type_change && fold_affected_mask(ctx, op, z_mask_old ^ z_mask)) { > + return true; > } > return fold_masks(ctx, op); > } > @@ -2482,8 +2495,8 @@ static bool fold_sextract(OptContext *ctx, TCGOp *op) > s_mask |= MAKE_64BIT_MASK(len, 64 - len); > ctx->s_mask = s_mask; > > - if (pos == 0) { > - ctx->a_mask = s_mask & ~s_mask_old; > + if (pos == 0 && fold_affected_mask(ctx, op, s_mask & ~s_mask_old)) { > + return true; > } > > return fold_masks(ctx, op); > @@ -2843,7 +2856,6 @@ void tcg_optimize(TCGContext *s) > } > > /* Assume all bits affected, no bits known zero, no sign reps. */ > - ctx.a_mask = -1; > ctx.z_mask = -1; > ctx.s_mask = 0; > Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
diff --git a/tcg/optimize.c b/tcg/optimize.c index 453e8c43bd..6757fe0036 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -64,7 +64,6 @@ typedef struct OptContext { QSIMPLEQ_HEAD(, MemCopyInfo) mem_free; /* In flight values from optimization. */ - uint64_t a_mask; /* mask bit is 0 iff value identical to first input */ uint64_t z_mask; /* mask bit is 0 iff value bit is 0 */ uint64_t s_mask; /* mask of clrsb(value) bits */ TCGType type; @@ -1047,7 +1046,6 @@ static bool fold_const2_commutative(OptContext *ctx, TCGOp *op) static bool fold_masks(OptContext *ctx, TCGOp *op) { - uint64_t a_mask = ctx->a_mask; uint64_t z_mask = ctx->z_mask; uint64_t s_mask = ctx->s_mask; @@ -1059,7 +1057,6 @@ static bool fold_masks(OptContext *ctx, TCGOp *op) * type changing opcodes. */ if (ctx->type == TCG_TYPE_I32) { - a_mask = (int32_t)a_mask; z_mask = (int32_t)z_mask; s_mask |= MAKE_64BIT_MASK(32, 32); ctx->z_mask = z_mask; @@ -1069,6 +1066,19 @@ static bool fold_masks(OptContext *ctx, TCGOp *op) if (z_mask == 0) { return tcg_opt_gen_movi(ctx, op, op->args[0], 0); } + return false; +} + +/* + * An "affected" mask bit is 0 if and only if the result is identical + * to the first input. Thus if the entire mask is 0, the operation + * is equivalent to a copy. + */ +static bool fold_affected_mask(OptContext *ctx, TCGOp *op, uint64_t a_mask) +{ + if (ctx->type == TCG_TYPE_I32) { + a_mask = (uint32_t)a_mask; + } if (a_mask == 0) { return tcg_opt_gen_mov(ctx, op, op->args[0], op->args[1]); } @@ -1305,8 +1315,9 @@ static bool fold_and(OptContext *ctx, TCGOp *op) * Known-zeros does not imply known-ones. Therefore unless * arg2 is constant, we can't infer affected bits from it. */ - if (arg_is_const(op->args[2])) { - ctx->a_mask = z1 & ~z2; + if (arg_is_const(op->args[2]) && + fold_affected_mask(ctx, op, z1 & ~z2)) { + return true; } return fold_masks(ctx, op); @@ -1331,7 +1342,9 @@ static bool fold_andc(OptContext *ctx, TCGOp *op) */ if (arg_is_const(op->args[2])) { uint64_t z2 = ~arg_info(op->args[2])->z_mask; - ctx->a_mask = z1 & ~z2; + if (fold_affected_mask(ctx, op, z1 & ~z2)) { + return true; + } z1 &= z2; } ctx->z_mask = z1; @@ -1709,8 +1722,8 @@ static bool fold_extract(OptContext *ctx, TCGOp *op) z_mask_old = arg_info(op->args[1])->z_mask; z_mask = extract64(z_mask_old, pos, len); - if (pos == 0) { - ctx->a_mask = z_mask_old ^ z_mask; + if (pos == 0 && fold_affected_mask(ctx, op, z_mask_old ^ z_mask)) { + return true; } ctx->z_mask = z_mask; ctx->s_mask = smask_from_zmask(z_mask); @@ -1777,8 +1790,8 @@ static bool fold_exts(OptContext *ctx, TCGOp *op) ctx->z_mask = z_mask; ctx->s_mask = s_mask; - if (!type_change) { - ctx->a_mask = s_mask & ~s_mask_old; + if (!type_change && fold_affected_mask(ctx, op, s_mask & ~s_mask_old)) { + return true; } return fold_masks(ctx, op); @@ -1819,8 +1832,8 @@ static bool fold_extu(OptContext *ctx, TCGOp *op) ctx->z_mask = z_mask; ctx->s_mask = smask_from_zmask(z_mask); - if (!type_change) { - ctx->a_mask = z_mask_old ^ z_mask; + if (!type_change && fold_affected_mask(ctx, op, z_mask_old ^ z_mask)) { + return true; } return fold_masks(ctx, op); } @@ -2482,8 +2495,8 @@ static bool fold_sextract(OptContext *ctx, TCGOp *op) s_mask |= MAKE_64BIT_MASK(len, 64 - len); ctx->s_mask = s_mask; - if (pos == 0) { - ctx->a_mask = s_mask & ~s_mask_old; + if (pos == 0 && fold_affected_mask(ctx, op, s_mask & ~s_mask_old)) { + return true; } return fold_masks(ctx, op); @@ -2843,7 +2856,6 @@ void tcg_optimize(TCGContext *s) } /* Assume all bits affected, no bits known zero, no sign reps. */ - ctx.a_mask = -1; ctx.z_mask = -1; ctx.s_mask = 0;
There are only a few logical operations which can compute an "affected" mask. Split out handling of this optimization to a separate function, only to be called when applicable. Remove the a_mask field from OptContext, as the mask is no longer stored anywhere. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- tcg/optimize.c | 42 +++++++++++++++++++++++++++--------------- 1 file changed, 27 insertions(+), 15 deletions(-)