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JavaScriptCoreのREPLがCygwinで動いた

okuokuokuoku

長く苦しい孤独な戦いだった。。

https://twitter.com/okuoku/status/1491356686011219969

まぁCygwinのpackageのパッチは有るんだけどね。。(ただし超古い)

例えば -g1 を指定するといったのは既に入っている。最終的にWebKitのCMakeは

cmake -GNinja -DCMAKE_BUILD_TYPE=Debug -DPORT=WPE -DWPE_INCLUDE_DIR=/cygdrive/f/webkit/proj/libwpe/include -DWPE_LIBRARY=/usr/lib/libelf.a -DUSE_SOUP2=ON -DENABLE_JOURNALD_LOG=OFF -DENABLE_JIT=OFF -DENABLE_C_LOOP=ON -DENABLE_SAMPLING_PROFILER=OFF -DENABLE_UNIFIED_BUILDS=OFF .

に加えて、

DEBUG_FISSION=OFF
USE_THIN_ARCHIVES=OFF
USE_SYSTEM_MALLOC=ON
CMAKE_C_COMPILER
CMAKE_CXX_COMPILER

あたりは調整が必要になった。あとARとRANLIBもLLVMのを使ったしCFLAGS/CXXFLAGSも調整してるな。。

okuokuokuoku

bmallocがクラッシュする

まぁbmallocはとりあえずナシで。。あんまり良い実装とも思わないし。。

(gdb) run
Starting program: /cygdrive/f/webkit/build/webkit/bin/jsc.exe
[New Thread 148484.0x3b4cc]
[New Thread 148484.0x2a65c]
[New Thread 148484.0x7798]
[New Thread 148484.0x1e4a4]
[New Thread 148484.0xb004]

Thread 1 "jsc" received signal SIGSEGV, Segmentation fault.
0x00000001014cd547 in bmalloc::SmallPage::ref(std::unique_lock<bmalloc::Mutex>&) () at /cygdrive/f/webkit/proj/WebKit/Source/bmalloc/bmalloc/SmallPage.h:83
83          BASSERT(m_refCount);
(gdb) bt
#0  0x00000001014cd547 in bmalloc::SmallPage::ref(std::unique_lock<bmalloc::Mutex>&) () at /cygdrive/f/webkit/proj/WebKit/Source/bmalloc/bmalloc/SmallPage.h:83
#1  0x0000000100aa305f in bmalloc::Heap::allocateSmallBumpRangesByMetadata(std::unique_lock<bmalloc::Mutex>&, unsigned long, bmalloc::BumpAllocator&, bmalloc::FixedVector<bmalloc::BumpRange, 3ul>&, std::array<bmalloc::List<bmalloc::SmallPage>, 112ul>&, bmalloc::FailureAction)::$_4::operator()(unsigned long&) const ()
    at /cygdrive/f/webkit/proj/WebKit/Source/bmalloc/bmalloc/Heap.cpp:409
#2  0x0000000100aa2dcd in bmalloc::Heap::allocateSmallBumpRangesByMetadata(std::unique_lock<bmalloc::Mutex>&, unsigned long, bmalloc::BumpAllocator&, bmalloc::FixedVector<bmalloc::BumpRange, 3ul>&, std::array<bmalloc::List<bmalloc::SmallPage>, 112ul>&, bmalloc::FailureAction) ()
    at /cygdrive/f/webkit/proj/WebKit/Source/bmalloc/bmalloc/Heap.cpp:429
#3  0x00000001014ca53c in bmalloc::Heap::allocateSmallBumpRanges(std::unique_lock<bmalloc::Mutex>&, unsigned long, bmalloc::BumpAllocator&, bmalloc::FixedVector<bmalloc::BumpRange, 3ul>&, std::array<bmalloc::List<bmalloc::SmallPage>, 112ul>&, bmalloc::FailureAction) ()
    at /cygdrive/f/webkit/proj/WebKit/Source/bmalloc/bmalloc/Heap.h:157
#4  0x0000000100a9ee8b in bmalloc::Allocator::refillAllocatorSlowCase(bmalloc::BumpAllocator&, unsigned long, bmalloc::FailureAction) ()

bmallocは USE_SYSTEM_MALLOC=ON でoffにできる。

okuokuokuoku

Cygwinのページサイズは64KiB

要出典。。

$ ./jsc.exe
ASSERTION FAILED: CeilingOnPageSize is too low, raise it in PageBlock.h!
%j
▒i(-15584) :
%s

Aborted (core dumped)

とりあえず 64KiBで。

diff --git a/Source/WTF/wtf/PageBlock.h b/Source/WTF/wtf/PageBlock.h
index 8ff8443d0e25..5b75078973a6 100644
--- a/Source/WTF/wtf/PageBlock.h
+++ b/Source/WTF/wtf/PageBlock.h
@@ -46,7 +46,7 @@ namespace WTF {
 // Use 64 KiB for any unknown CPUs to be conservative.
 #if OS(DARWIN) || PLATFORM(PLAYSTATION) || CPU(MIPS) || CPU(MIPS64)
 constexpr size_t CeilingOnPageSize = 16 * KB;
-#elif CPU(PPC) || CPU(PPC64) || CPU(PPC64LE) || CPU(UNKNOWN)
+#elif CPU(PPC) || CPU(PPC64) || CPU(PPC64LE) || CPU(UNKNOWN) || defined(__CYGWIN__)
 constexpr size_t CeilingOnPageSize = 64 * KB;
 #elif OS(WINDOWS) || CPU(X86) || CPU(X86_64) || CPU(ARM) || CPU(ARM64) || CPU(RISCV64)
 constexpr size_t CeilingOnPageSize = 4 * KB;

alignas に64KiBとか渡せない

このままだとビルド時にエラーになる。

https://github.com/WebKit/WebKit/blob/8afe31a018b11741abdf9b4d5bb973d7c1d9ff05/Source/WTF/wtf/PageBlock.cpp#L47

/cygdrive/f/webkit/proj/WebKit/Source/WTF/wtf/WTFConfig.cpp:46:1: error: requested alignment must be 8192 bytes or smaller
alignas(WTF::ConfigAlignment) Slot g_config[WTF::ConfigSizeToProtect / sizeof(Slot)];
^       ~~~~~~~~~~~~~~~~~~~~
1 error generated.

まぁWindowsではこのコードを使っていないようなので、Cygwinでも同様に。

diff --git a/Source/WTF/wtf/PlatformEnable.h b/Source/WTF/wtf/PlatformEnable.h
index 664b0e29f6ba..38cb8ae26901 100644
--- a/Source/WTF/wtf/PlatformEnable.h
+++ b/Source/WTF/wtf/PlatformEnable.h
@@ -804,7 +804,7 @@
    disable both the use of unified Config record and config freezing for the
    Windows port.
 */
-#if OS(WINDOWS)
+#if OS(WINDOWS) || defined(__CYGWIN__)
 #define ENABLE_UNIFIED_AND_FREEZABLE_CONFIG_RECORD 0
 #else
 #define ENABLE_UNIFIED_AND_FREEZABLE_CONFIG_RECORD 1