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https://github.com/vercel-labs/scriptc.git
synced 2026-11-08 08:44:37 +08:00
Chris Tate
6715609695
Partitions were filled by a hash of each function's name, so most calls crossed partitions and the thin link imported their small callees into nearly every partition. The emitter now writes a "; scriptc-group" line before the functions of each source file, and the text partitioner places a group's functions together: a group larger than the mean partition, or than 1 MiB, is divided into a power of two of chunks by name, and chunks go, largest first, to the lighter of two partitions chosen by hash. The 1 MiB bound keeps the code a partition optimizes together, and the inlining within it, from growing when a program has fewer partitions. Modules with fewer than 32 partitions, and functions without a group, keep their name-hash placement: with few partitions per core, the balance of the largest partitions decides the build time more than the imports. The placement still depends only on the module text and the partition count.
36 lines
1.5 KiB
C++
36 lines
1.5 KiB
C++
#pragma once
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/StringSet.h"
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#include <optional>
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#include <string>
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#include <vector>
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namespace scriptc {
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// A program module divided into independently compilable textual modules.
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struct ProgramPartitions {
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// One complete LLVM assembly module per partition.
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std::vector<std::string> Sources;
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// Definitions that were not internal in the original module. Every other
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// definition was internal and is promoted to hidden visibility only so the
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// partitions can reference each other.
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llvm::StringSet<> PublicSymbols;
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};
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// Divides the LLVM assembly scriptc emits into Count modules without parsing
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// it, so the partitions can be parsed concurrently. In modules of 32 or
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// more partitions, functions under a "; scriptc-group <key>" line are placed
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// with the other functions of that source-module group, which is divided
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// into chunks when it is larger than the mean partition or 1 MiB; other
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// functions are placed by a stable hash of their name. An internal function referenced by exactly one other function stays
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// with that function unless its body is too large to inline, and a global
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// stays with the first function that references it. Returns nullopt for any
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// construct outside the emitter's narrow top-level grammar; callers then
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// split a parsed module.
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std::optional<ProgramPartitions> partitionProgramText(llvm::StringRef Text,
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unsigned Count);
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} // namespace scriptc
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