| Message ID | 20240228110626.287178-1-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | tcg/optimize: lower some ANDs to two shifts | expand |
Sorry, that was sent incorrectly. Paolo On Wed, Feb 28, 2024 at 12:06 PM Paolo Bonzini <pbonzini@redhat.com> wrote: > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > tcg/optimize.c | 60 +++++++++++++++++++++++++++++++++++++++++++------- > 1 file changed, 52 insertions(+), 8 deletions(-) > > diff --git a/tcg/optimize.c b/tcg/optimize.c > index 3995bc047db..8ea1f287788 100644 > --- a/tcg/optimize.c > +++ b/tcg/optimize.c > @@ -1281,6 +1281,43 @@ static bool fold_add2(OptContext *ctx, TCGOp *op) > return fold_addsub2(ctx, op, true); > } > > +static bool fold_and_to_shifts(OptContext *ctx, uint64_t c, TCGOp *op) > +{ > + TCGOpcode shl_opc = tcg->type == TCG_TYPE_I32 ? INDEX_op_shl_i32 : INDEX_op_shl_i64; > + TCGOpcode shr_opc = tcg->type == TCG_TYPE_I32 ? INDEX_op_shr_i32 : INDEX_op_shr_i64; > + > + TCGOpcode first, second; > + int count; > + TCGOp *op2; > + > + unsigned_c = tcg->type == TCG_TYPE_I32 ? (uint32_t) c : c; > + if (is_power_of_2(-c) && > + !tcg_op_imm_match(op->opc, c)) { > + /* AND with 11...11000, shift right then left. */ > + count = ctz64(c); > + first = shr_opc; > + } else if (is_power_of_2(c + 1) && > + !tcg_op_imm_match(INDEX_op_and_i64, c)) { > + /* AND with 00...00111, shift left then right. */ > + int bits = tcg->type == TCG_TYPE_I32 ? 32 : 64; > + count = bits - cto64(c); > + first = shl_opc; > + } else { > + return false; > + } > + > + > + op->opc = first; > + op->args[2] = arg_new_constant(ctx, count); > + > + second = shl_opc ^ shr_opc ^ first; > + op2 = tcg_op_insert_after(ctx->tcg, op, second, 3); > + op2->args[0] = op->args[0]; > + op2->args[1] = op->args[0]; > + op2->args[2] = arg_new_constant(ctx, count); > + return true; > +} > + > static bool fold_and(OptContext *ctx, TCGOp *op) > { > uint64_t z1, z2; > @@ -1294,6 +1331,18 @@ static bool fold_and(OptContext *ctx, TCGOp *op) > > z1 = arg_info(op->args[1])->z_mask; > z2 = arg_info(op->args[2])->z_mask; > + > + /* > + * 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])) { > + if (fold_and_to_shifts(ctx, z2, op)) { > + return true; > + } > + ctx->a_mask = z1 & ~z2; > + } > + > ctx->z_mask = z1 & z2; > > /* > @@ -1303,14 +1352,6 @@ static bool fold_and(OptContext *ctx, TCGOp *op) > ctx->s_mask = arg_info(op->args[1])->s_mask > & arg_info(op->args[2])->s_mask; > > - /* > - * 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; > - } > - > return fold_masks(ctx, op); > } > > @@ -1333,6 +1374,9 @@ 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; > + if (fold_and_to_shifts(ctx, z2, op)) { > + return true; > + } > ctx->a_mask = z1 & ~z2; > z1 &= z2; > } > -- > 2.43.2
diff --git a/tcg/optimize.c b/tcg/optimize.c index 3995bc047db..8ea1f287788 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -1281,6 +1281,43 @@ static bool fold_add2(OptContext *ctx, TCGOp *op) return fold_addsub2(ctx, op, true); } +static bool fold_and_to_shifts(OptContext *ctx, uint64_t c, TCGOp *op) +{ + TCGOpcode shl_opc = tcg->type == TCG_TYPE_I32 ? INDEX_op_shl_i32 : INDEX_op_shl_i64; + TCGOpcode shr_opc = tcg->type == TCG_TYPE_I32 ? INDEX_op_shr_i32 : INDEX_op_shr_i64; + + TCGOpcode first, second; + int count; + TCGOp *op2; + + unsigned_c = tcg->type == TCG_TYPE_I32 ? (uint32_t) c : c; + if (is_power_of_2(-c) && + !tcg_op_imm_match(op->opc, c)) { + /* AND with 11...11000, shift right then left. */ + count = ctz64(c); + first = shr_opc; + } else if (is_power_of_2(c + 1) && + !tcg_op_imm_match(INDEX_op_and_i64, c)) { + /* AND with 00...00111, shift left then right. */ + int bits = tcg->type == TCG_TYPE_I32 ? 32 : 64; + count = bits - cto64(c); + first = shl_opc; + } else { + return false; + } + + + op->opc = first; + op->args[2] = arg_new_constant(ctx, count); + + second = shl_opc ^ shr_opc ^ first; + op2 = tcg_op_insert_after(ctx->tcg, op, second, 3); + op2->args[0] = op->args[0]; + op2->args[1] = op->args[0]; + op2->args[2] = arg_new_constant(ctx, count); + return true; +} + static bool fold_and(OptContext *ctx, TCGOp *op) { uint64_t z1, z2; @@ -1294,6 +1331,18 @@ static bool fold_and(OptContext *ctx, TCGOp *op) z1 = arg_info(op->args[1])->z_mask; z2 = arg_info(op->args[2])->z_mask; + + /* + * 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])) { + if (fold_and_to_shifts(ctx, z2, op)) { + return true; + } + ctx->a_mask = z1 & ~z2; + } + ctx->z_mask = z1 & z2; /* @@ -1303,14 +1352,6 @@ static bool fold_and(OptContext *ctx, TCGOp *op) ctx->s_mask = arg_info(op->args[1])->s_mask & arg_info(op->args[2])->s_mask; - /* - * 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; - } - return fold_masks(ctx, op); } @@ -1333,6 +1374,9 @@ 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; + if (fold_and_to_shifts(ctx, z2, op)) { + return true; + } ctx->a_mask = z1 & ~z2; z1 &= z2; }
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- tcg/optimize.c | 60 +++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 52 insertions(+), 8 deletions(-)