From: Ian Lance Taylor Date: Fri, 15 Mar 2019 04:34:43 +0000 (+0000) Subject: compiler: eliminate bound checks in append expression X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b1403b691a24fae2a96fa7ce5b93c3395e7bfd05;p=gcc.git compiler: eliminate bound checks in append expression The compiler generates two array index expressions when lowering an append expression. Currently they generate bound checks. Bound checks are not necessary in this case, as we know the slice has, or will grow to, enough length and capacity. Eliminate them. Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/166817 From-SVN: r269699 --- diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE index f3c52bfaa86..61bcab29e67 100644 --- a/gcc/go/gofrontend/MERGE +++ b/gcc/go/gofrontend/MERGE @@ -1,4 +1,4 @@ -946aa5ab2e82d045a2a3b2f18ba2c5b00e957c4b +80a7f6dae0861a06407a44c501b6346a4abd119c The first line of this file holds the git revision number of the last merge done from the gofrontend repository. diff --git a/gcc/go/gofrontend/expressions.cc b/gcc/go/gofrontend/expressions.cc index f32b7a4b1b9..f41647aa4e4 100644 --- a/gcc/go/gofrontend/expressions.cc +++ b/gcc/go/gofrontend/expressions.cc @@ -8008,8 +8008,8 @@ Builtin_call_expression::flatten_append(Gogo* gogo, Named_object* function, ref = Expression::make_temporary_reference(s1tmp, loc); Expression* zero = Expression::make_integer_ul(0, int_type, loc); Expression* ref2 = Expression::make_temporary_reference(ntmp, loc); - // FIXME: Mark this index as not requiring bounds checks. - ref = Expression::make_index(ref, zero, ref2, NULL, loc); + ref = Expression::make_array_index(ref, zero, ref2, NULL, loc); + ref->array_index_expression()->set_needs_bounds_check(false); if (assign_lhs == NULL) { @@ -8058,8 +8058,8 @@ Builtin_call_expression::flatten_append(Gogo* gogo, Named_object* function, a1 = Expression::make_temporary_reference(s1tmp, loc); ref = Expression::make_temporary_reference(l1tmp, loc); Expression* nil = Expression::make_nil(loc); - // FIXME: Mark this index as not requiring bounds checks. - a1 = Expression::make_index(a1, ref, nil, NULL, loc); + a1 = Expression::make_array_index(a1, ref, nil, NULL, loc); + a1->array_index_expression()->set_needs_bounds_check(false); a2 = Expression::make_temporary_reference(s2tmp, loc); @@ -8086,9 +8086,9 @@ Builtin_call_expression::flatten_append(Gogo* gogo, Named_object* function, ref2 = Expression::make_temporary_reference(l1tmp, loc); Expression* off = Expression::make_integer_ul(i, int_type, loc); ref2 = Expression::make_binary(OPERATOR_PLUS, ref2, off, loc); - // FIXME: Mark this index as not requiring bounds checks. - Expression* lhs = Expression::make_index(ref, ref2, NULL, NULL, - loc); + Expression* lhs = Expression::make_array_index(ref, ref2, NULL, + NULL, loc); + lhs->array_index_expression()->set_needs_bounds_check(false); gogo->lower_expression(function, inserter, &lhs); gogo->flatten_expression(function, inserter, &lhs); // The flatten pass runs after the write barrier pass, so we @@ -11328,15 +11328,6 @@ Array_index_expression::do_get_backend(Translate_context* context) if (length == NULL) length = cap_arg; - int code = (array_type->length() != NULL - ? (this->end_ == NULL - ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS - : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS) - : (this->end_ == NULL - ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS - : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS)); - Bexpression* crash = gogo->runtime_error(code, loc)->get_backend(context); - if (this->start_->type()->integer_type() == NULL && !Type::are_convertible(int_type, this->start_->type(), NULL)) { @@ -11344,31 +11335,46 @@ Array_index_expression::do_get_backend(Translate_context* context) return context->backend()->error_expression(); } - Bexpression* bad_index = - Expression::check_bounds(this->start_, loc)->get_backend(context); - Bexpression* start = this->start_->get_backend(context); start = gogo->backend()->convert_expression(int_btype, start, loc); - Bexpression* start_too_large = - gogo->backend()->binary_expression((this->end_ == NULL - ? OPERATOR_GE - : OPERATOR_GT), - start, - (this->end_ == NULL - ? length - : capacity), - loc); - bad_index = gogo->backend()->binary_expression(OPERATOR_OROR, start_too_large, - bad_index, loc); + + Bexpression* crash = NULL; + Bexpression* bad_index = NULL; + if (this->needs_bounds_check_) + { + int code = (array_type->length() != NULL + ? (this->end_ == NULL + ? RUNTIME_ERROR_ARRAY_INDEX_OUT_OF_BOUNDS + : RUNTIME_ERROR_ARRAY_SLICE_OUT_OF_BOUNDS) + : (this->end_ == NULL + ? RUNTIME_ERROR_SLICE_INDEX_OUT_OF_BOUNDS + : RUNTIME_ERROR_SLICE_SLICE_OUT_OF_BOUNDS)); + crash = gogo->runtime_error(code, loc)->get_backend(context); + bad_index = Expression::check_bounds(this->start_, loc)->get_backend(context); + Bexpression* start_too_large = + gogo->backend()->binary_expression((this->end_ == NULL + ? OPERATOR_GE + : OPERATOR_GT), + start, + (this->end_ == NULL + ? length + : capacity), + loc); + bad_index = gogo->backend()->binary_expression(OPERATOR_OROR, + start_too_large, + bad_index, loc); + } + Bfunction* bfn = context->function()->func_value()->get_decl(); if (this->end_ == NULL) { // Simple array indexing. This has to return an l-value, so // wrap the index check into START. - start = - gogo->backend()->conditional_expression(bfn, int_btype, bad_index, - crash, start, loc); + if (this->needs_bounds_check_) + start = + gogo->backend()->conditional_expression(bfn, int_btype, bad_index, + crash, start, loc); Bexpression* ret; if (array_type->length() != NULL) @@ -11396,22 +11402,26 @@ Array_index_expression::do_get_backend(Translate_context* context) if (this->cap_ != NULL) { - Bexpression* bounds_bcheck = - Expression::check_bounds(this->cap_, loc)->get_backend(context); - bad_index = - gogo->backend()->binary_expression(OPERATOR_OROR, bounds_bcheck, - bad_index, loc); cap_arg = gogo->backend()->convert_expression(int_btype, cap_arg, loc); - Bexpression* cap_too_small = - gogo->backend()->binary_expression(OPERATOR_LT, cap_arg, start, loc); - Bexpression* cap_too_large = - gogo->backend()->binary_expression(OPERATOR_GT, cap_arg, capacity, loc); - Bexpression* bad_cap = - gogo->backend()->binary_expression(OPERATOR_OROR, cap_too_small, - cap_too_large, loc); - bad_index = gogo->backend()->binary_expression(OPERATOR_OROR, bad_cap, - bad_index, loc); + if (this->needs_bounds_check_) + { + Bexpression* bounds_bcheck = + Expression::check_bounds(this->cap_, loc)->get_backend(context); + bad_index = + gogo->backend()->binary_expression(OPERATOR_OROR, bounds_bcheck, + bad_index, loc); + + Bexpression* cap_too_small = + gogo->backend()->binary_expression(OPERATOR_LT, cap_arg, start, loc); + Bexpression* cap_too_large = + gogo->backend()->binary_expression(OPERATOR_GT, cap_arg, capacity, loc); + Bexpression* bad_cap = + gogo->backend()->binary_expression(OPERATOR_OROR, cap_too_small, + cap_too_large, loc); + bad_index = gogo->backend()->binary_expression(OPERATOR_OROR, bad_cap, + bad_index, loc); + } } Bexpression* end; @@ -11419,24 +11429,26 @@ Array_index_expression::do_get_backend(Translate_context* context) end = length; else { - Bexpression* bounds_bcheck = - Expression::check_bounds(this->end_, loc)->get_backend(context); - - bad_index = - gogo->backend()->binary_expression(OPERATOR_OROR, bounds_bcheck, - bad_index, loc); - end = this->end_->get_backend(context); end = gogo->backend()->convert_expression(int_btype, end, loc); - Bexpression* end_too_small = - gogo->backend()->binary_expression(OPERATOR_LT, end, start, loc); - Bexpression* end_too_large = - gogo->backend()->binary_expression(OPERATOR_GT, end, cap_arg, loc); - Bexpression* bad_end = - gogo->backend()->binary_expression(OPERATOR_OROR, end_too_small, - end_too_large, loc); - bad_index = gogo->backend()->binary_expression(OPERATOR_OROR, bad_end, - bad_index, loc); + if (this->needs_bounds_check_) + { + Bexpression* bounds_bcheck = + Expression::check_bounds(this->end_, loc)->get_backend(context); + bad_index = + gogo->backend()->binary_expression(OPERATOR_OROR, bounds_bcheck, + bad_index, loc); + + Bexpression* end_too_small = + gogo->backend()->binary_expression(OPERATOR_LT, end, start, loc); + Bexpression* end_too_large = + gogo->backend()->binary_expression(OPERATOR_GT, end, cap_arg, loc); + Bexpression* bad_end = + gogo->backend()->binary_expression(OPERATOR_OROR, end_too_small, + end_too_large, loc); + bad_index = gogo->backend()->binary_expression(OPERATOR_OROR, bad_end, + bad_index, loc); + } } Bexpression* result_length = @@ -11468,10 +11480,12 @@ Array_index_expression::do_get_backend(Translate_context* context) init.push_back(result_length); init.push_back(result_capacity); - Bexpression* ctor = + Bexpression* ret = gogo->backend()->constructor_expression(struct_btype, init, loc); - return gogo->backend()->conditional_expression(bfn, struct_btype, bad_index, - crash, ctor, loc); + if (this->needs_bounds_check_) + ret = gogo->backend()->conditional_expression(bfn, struct_btype, bad_index, + crash, ret, loc); + return ret; } // Dump ast representation for an array index expression. diff --git a/gcc/go/gofrontend/expressions.h b/gcc/go/gofrontend/expressions.h index 5d61b69c0fa..c521d9bf775 100644 --- a/gcc/go/gofrontend/expressions.h +++ b/gcc/go/gofrontend/expressions.h @@ -2854,7 +2854,7 @@ class Array_index_expression : public Expression Expression* end, Expression* cap, Location location) : Expression(EXPRESSION_ARRAY_INDEX, location), array_(array), start_(start), end_(end), cap_(cap), type_(NULL), - is_lvalue_(false) + is_lvalue_(false), needs_bounds_check_(true) { } // Return the array. @@ -2898,6 +2898,10 @@ class Array_index_expression : public Expression set_is_lvalue() { this->is_lvalue_ = true; } + void + set_needs_bounds_check(bool b) + { this->needs_bounds_check_ = b; } + protected: int do_traverse(Traverse*); @@ -2917,15 +2921,17 @@ class Array_index_expression : public Expression Expression* do_copy() { - return Expression::make_array_index(this->array_->copy(), - this->start_->copy(), - (this->end_ == NULL - ? NULL - : this->end_->copy()), - (this->cap_ == NULL - ? NULL - : this->cap_->copy()), - this->location()); + Expression* ret = Expression::make_array_index(this->array_->copy(), + this->start_->copy(), + (this->end_ == NULL + ? NULL + : this->end_->copy()), + (this->cap_ == NULL + ? NULL + : this->cap_->copy()), + this->location()); + ret->array_index_expression()->set_needs_bounds_check(this->needs_bounds_check_); + return ret; } bool @@ -2962,6 +2968,8 @@ class Array_index_expression : public Expression Type* type_; // Whether expr appears in an lvalue context. bool is_lvalue_; + // Whether bounds check is needed. + bool needs_bounds_check_; }; // A string index. This is used for both indexing and slicing.