mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 22:02:23 +01:00
4845f40dff
This switches `DCHECK` and `FATAL` as well. The goal is to reduce the code size impact of these assertions so that we can keep more of them enabled. Currently, the largest cost I see from `CHECK` is not the actual check or the cold code itself, but actually the failure to inline trivial functions due to the presence of the cold code. This means that our goal isn't to reduce apparent code size in the final binary but the LLVM IR cost assessed for these routines in the inliner, which closely correlates with code size but is a bit different. As discussed in #4283, experimentation shows that a single function call with a minimal number of arguments is the lowest cost model for these. This is easily achieved with a format-string API that internally uses `llvm::formatv`. This PR is essentially the `CHECK` version of #4283. However, the check macros are substantially harder to make work with both format strings and streaming because they also take a condition. Also, unexpectedly, I was very successful at devising a regular expression based automated rewrite from the streaming to the format string form with only low 10s of manual fixes. This includes compacting strings broken up across lines, etc. Given how well that went, I've prepared this PR which just directly switches to the format string API and migrate everything to use it. One nice side-effect is that the format string approach ends up greatly simplifying the implementation here as well. This is ... *shockingly* effective. Parsing speeds up by more than 3% with just this change. And checking speeds up by **8%** with this change alone: ``` BM_CompileAPIFileDenseDecls<Phase::Parse>/256 86.3µs ± 1% 82.9µs ± 1% -3.94% (p=0.000 n=17+19) BM_CompileAPIFileDenseDecls<Phase::Parse>/1024 431µs ± 1% 415µs ± 1% -3.76% (p=0.000 n=18+19) BM_CompileAPIFileDenseDecls<Phase::Parse>/4096 1.77ms ± 1% 1.71ms ± 1% -3.18% (p=0.000 n=18+19) BM_CompileAPIFileDenseDecls<Phase::Parse>/16384 7.44ms ± 1% 7.17ms ± 2% -3.56% (p=0.000 n=18+20) BM_CompileAPIFileDenseDecls<Phase::Parse>/65536 30.7ms ± 1% 29.7ms ± 1% -3.15% (p=0.000 n=18+20) BM_CompileAPIFileDenseDecls<Phase::Parse>/262144 131ms ± 1% 127ms ± 1% -2.81% (p=0.000 n=18+18) BM_CompileAPIFileDenseDecls<Phase::Check>/256 878µs ± 2% 800µs ± 1% -8.91% (p=0.000 n=19+20) BM_CompileAPIFileDenseDecls<Phase::Check>/1024 1.88ms ± 2% 1.72ms ± 1% -8.56% (p=0.000 n=19+20) BM_CompileAPIFileDenseDecls<Phase::Check>/4096 5.78ms ± 2% 5.28ms ± 1% -8.70% (p=0.000 n=20+18) BM_CompileAPIFileDenseDecls<Phase::Check>/16384 21.9ms ± 1% 20.1ms ± 1% -8.02% (p=0.000 n=18+20) BM_CompileAPIFileDenseDecls<Phase::Check>/65536 90.4ms ± 2% 83.1ms ± 1% -8.04% (p=0.000 n=19+20) BM_CompileAPIFileDenseDecls<Phase::Check>/262144 381ms ± 2% 352ms ± 1% -7.79% (p=0.000 n=19+19) ``` --------- Co-authored-by: Richard Smith <richard@metafoo.co.uk> Co-authored-by: josh11b <15258583+josh11b@users.noreply.github.com>
91 lines
2.9 KiB
C++
91 lines
2.9 KiB
C++
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
|
|
// Exceptions. See /LICENSE for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
|
|
#ifndef CARBON_COMMON_ARRAY_STACK_H_
|
|
#define CARBON_COMMON_ARRAY_STACK_H_
|
|
|
|
#include "common/check.h"
|
|
#include "llvm/ADT/ArrayRef.h"
|
|
#include "llvm/ADT/SmallVector.h"
|
|
|
|
namespace Carbon {
|
|
|
|
// Provides a stack of arrays. Only the array at the top of the stack can have
|
|
// elements added.
|
|
//
|
|
// Example usage:
|
|
// // Push to start.
|
|
// PushArray();
|
|
// // Add values.
|
|
// AppendToTop(3);
|
|
// // Look at values.
|
|
// PeekArray();
|
|
// // Pop when done.
|
|
// PopArray();
|
|
//
|
|
// By using a single vector for elements, the intent is that as arrays are
|
|
// pushed and popped, the same storage will be reused. This should yield
|
|
// efficiencies for heap allocations. For example, in the toolchain we
|
|
// frequently have an array per scope, and only add to the current scope's
|
|
// array; this allows better reuse when entering and leaving scopes.
|
|
template <typename ValueT>
|
|
class ArrayStack {
|
|
public:
|
|
// Pushes a new array onto the stack.
|
|
auto PushArray() -> void { array_offsets_.push_back(values_.size()); }
|
|
|
|
// Pops the top array from the stack.
|
|
auto PopArray() -> void {
|
|
auto region = array_offsets_.pop_back_val();
|
|
values_.truncate(region);
|
|
}
|
|
|
|
// Returns the top array from the stack.
|
|
auto PeekArray() const -> llvm::ArrayRef<ValueT> {
|
|
CARBON_CHECK(!array_offsets_.empty());
|
|
return llvm::ArrayRef(values_).slice(array_offsets_.back());
|
|
}
|
|
|
|
// Returns the array at a specific index.
|
|
auto PeekArrayAt(int index) const -> llvm::ArrayRef<ValueT> {
|
|
auto ref = llvm::ArrayRef(values_).slice(array_offsets_[index]);
|
|
if (index + 1 < static_cast<int>(array_offsets_.size())) {
|
|
ref = ref.take_front(array_offsets_[index + 1] - array_offsets_[index]);
|
|
}
|
|
return ref;
|
|
}
|
|
|
|
// Returns the full set of values on the stack, regardless of whether any
|
|
// arrays are pushed.
|
|
auto PeekAllValues() const -> llvm::ArrayRef<ValueT> { return values_; }
|
|
|
|
// Appends a value to the top array on the stack.
|
|
auto AppendToTop(ValueT value) -> void {
|
|
CARBON_CHECK(!array_offsets_.empty(),
|
|
"Must call PushArray before PushValue.");
|
|
values_.push_back(value);
|
|
}
|
|
|
|
// Adds multiple values to the top array on the stack.
|
|
auto AppendToTop(llvm::ArrayRef<ValueT> values) -> void {
|
|
CARBON_CHECK(!array_offsets_.empty(),
|
|
"Must call PushArray before PushValues.");
|
|
values_.append(values.begin(), values.end());
|
|
}
|
|
|
|
// Returns the current number of values in all arrays.
|
|
auto all_values_size() const -> size_t { return values_.size(); }
|
|
|
|
private:
|
|
// For each pushed array, the start index in elements_.
|
|
llvm::SmallVector<int32_t> array_offsets_;
|
|
|
|
// The full set of elements in all arrays.
|
|
llvm::SmallVector<ValueT> values_;
|
|
};
|
|
|
|
} // namespace Carbon
|
|
|
|
#endif // CARBON_COMMON_ARRAY_STACK_H_
|