f02b1cc99e
Currently, any FileID that references a module map file that was required for a compilation is considered as affecting. This misses an important opportunity to reduce the source location space taken by the resulting PCM. In particular, consider the situation where the same module map file is passed multiple times in the dependency chain: ```shell $ clang -fmodule-map-file=foo.modulemap ... -o mod1.pcm $ clang -fmodule-map-file=foo.modulemap -fmodule-file=mod1.pcm ... -o mod2.pcm ... $ clang -fmodule-map-file=foo.modulemap -fmodule-file=mod$((N-1)).pcm ... -o mod$N.pcm ``` Because `foo.modulemap` is read before reading any of the `.pcm` files, we have to create a unique `FileID` for it when creating each module. However, when reading the `.pcm` files, we will reuse the `FileID` loaded from it for the same module map file and the `FileID` we created can never be used again, but we will still mark it as affecting and it will take the source location space in the output PCM. For a chain of N dependencies, this results in the file taking `N * (size of file)` source location space, which could be significant. For examples, we observer internally that some targets that run out of 2GB of source location space end up wasting up to 20% of that space in module maps as described above. I take extra care to still write the InputFile entries for those files that occupied source location space before. It is required for correctness of clang-scan-deps.
86 lines
3.0 KiB
C++
86 lines
3.0 KiB
C++
// Check that the same module map file passed to -fmodule-map-file *and*
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// available from one of the `-fmodule-file` does not allocate extra source
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// location space. This optimization is important for using module maps in
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// large codebases to avoid running out of source location space.
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// RUN: rm -rf %t && mkdir %t
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// RUN: split-file %s %t
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// RUN: %clang_cc1 -xc++ -fmodules -fno-implicit-modules -fmodule-map-file=%t/base.map -fmodule-name=base -emit-module %t/base.map -o %t/base.pcm
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// RUN: %clang_cc1 -xc++ -fmodules -fno-implicit-modules \
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// RUN: -fmodule-map-file=%t/base.map -fmodule-map-file=%t/mod1.map \
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// RUN: -fmodule-file=%t/base.pcm \
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// RUN: -fmodule-name=mod1 -emit-module %t/mod1.map -o %t/mod1.pcm
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// RUN: %clang_cc1 -xc++ -fmodules -fno-implicit-modules \
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// RUN: -fmodule-map-file=%t/base.map -fmodule-map-file=%t/mod1.map -fmodule-map-file=%t/mod2.map \
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// RUN: -fmodule-file=%t/mod1.pcm \
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// RUN: -fmodule-name=mod2 -emit-module %t/mod2.map -o %t/mod2.pcm
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// RUN: %clang_cc1 -xc++ -fmodules -fno-implicit-modules \
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// RUN: -fmodule-map-file=%t/base.map -fmodule-map-file=%t/mod2.map -fmodule-map-file=%t/mod3.map \
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// RUN: -fmodule-file=%t/mod2.pcm \
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// RUN: -fmodule-name=mod3 -emit-module %t/mod3.map -o %t/mod3.pcm
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// RUN: %clang_cc1 -xc++ -fmodules -fno-implicit-modules \
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// RUN: -fmodule-map-file=%t/base.map -fmodule-map-file=%t/mod3.map -fmodule-map-file=%t/mod4.map \
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// RUN: -fmodule-file=%t/mod3.pcm \
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// RUN: -fmodule-name=mod4 -emit-module %t/mod4.map -o %t/mod4.pcm
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// RUN: %clang_cc1 -xc++ -fmodules -fno-implicit-modules -fmodule-map-file=%t/base.map -fmodule-map-file=%t/mod4.map -fmodule-file=%t/mod4.pcm -fsyntax-only -verify %t/check_slocs.cc
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//--- base.map
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module base { header "vector.h" }
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//--- mod1.map
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module mod1 { header "mod1.h" }
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//--- mod2.map
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module mod2 { header "mod2.h" }
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//--- mod3.map
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module mod3 { header "mod3.h" }
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//--- mod4.map
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module mod4 { header "mod4.h" }
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//--- check_slocs.cc
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#include "mod4.h"
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#pragma clang __debug sloc_usage // expected-remark {{source manager location address space usage}}
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// expected-note@* {{% of available space}}
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// Module map files files that were specified on the command line are entered twice (once when parsing command-line, once loaded from the .pcm)
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// Those that not specified on the command line must be entered once.
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// expected-note@base.map:1 {{file entered 2 times}}
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// expected-note@mod4.map:1 {{file entered 2 times}}
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// expected-note@mod1.map:1 {{file entered 1 time}}
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// expected-note@mod2.map:1 {{file entered 1 time}}
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// expected-note@mod3.map:1 {{file entered 1 time}}
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// expected-note@* + {{file entered}}
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//--- vector.h
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#ifndef VECTOR_H
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#define VECTOR_H
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#endif
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//--- mod1.h
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#ifndef MOD1
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#define MOD1
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#include "vector.h"
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int mod1();
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#endif
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//--- mod2.h
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#ifndef MOD2
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#define MOD2
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#include "vector.h"
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#include "mod1.h"
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int mod2();
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#endif
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//--- mod3.h
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#ifndef MOD3
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#define MOD3
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#include "vector.h"
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#include "mod2.h"
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int mod3();
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#endif
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//--- mod4.h
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#ifndef MOD4
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#define MOD4
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#include "vector.h"
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#include "mod3.h"
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int mod4();
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#endif
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