Changeset 44514 in webkit for trunk/JavaScriptCore/assembler/MacroAssemblerCodeRef.h

Timestamp:

Jun 8, 2009, 6:40:59 PM (16 years ago)

Author:

[email protected]

Message:

2009-06-08 Gavin Barraclough <​[email protected]>

Reviewed by Geoff Garen.

Add (incomplete) support to YARR for running with the jit enabled
on Arm thumb2 platforms. Adds new Assembler/MacroAssembler classes,
along with cache flushing support, tweaks to MacroAssemblerCodePtr
to support decorated thumb code pointers, and new enter/exit code
to YARR jit for the platform.

Support for this platform is still under development - the assembler
currrently only supports planting and linking jumps with a 16Mb range.
As such, initially commiting in a disabled state.

• JavaScriptCore.xcodeproj/project.pbxproj:

Add new assembler files.

• assembler/ARMv7Assembler.h: Added.

Add new Assembler.

• assembler/AbstractMacroAssembler.h:

Tweaks to ensure sizes of pointer values planted in JIT code do not change.

• assembler/MacroAssembler.h:

On ARMv7 platforms use MacroAssemblerARMv7.

• assembler/MacroAssemblerARMv7.h: Added.

Add new MacroAssembler.

• assembler/MacroAssemblerCodeRef.h: (JSC::FunctionPtr::FunctionPtr):

Add better ASSERT.

(JSC::ReturnAddressPtr::ReturnAddressPtr):

Add better ASSERT.

(JSC::MacroAssemblerCodePtr::MacroAssemblerCodePtr):

On ARMv7, MacroAssemblerCodePtr's mush be 'decorated' with a low bit set,
to indicate to the processor that the code is thumb code, not traditional
32-bit ARM.

(JSC::MacroAssemblerCodePtr::dataLocation):

On ARMv7, decoration must be removed.

• jit/ExecutableAllocator.h: (JSC::ExecutableAllocator::makeWritable):

Reformatted, no change.

(JSC::ExecutableAllocator::makeExecutable):

When marking code executable also cache flush it, where necessary.

(JSC::ExecutableAllocator::MakeWritable::MakeWritable):

Only use the null implementation of this class if both !ASSEMBLER_WX_EXCLUSIVE
and running on x86(_64) - on other platforms we may also need ensure that
makeExecutable is called at the end to flush caches.

(JSC::ExecutableAllocator::reprotectRegion):

Reformatted, no change.

(JSC::ExecutableAllocator::cacheFlush):

Cache flush a region of memory, or platforms where this is necessary.

• wtf/Platform.h:

Add changes necessary to allow YARR jit to build on this platform, disabled.

• yarr/RegexJIT.cpp: (JSC::Yarr::RegexGenerator::generateEnter): (JSC::Yarr::RegexGenerator::generateReturn):

Add support to these methods for ARMv7.

File:

• trunk/JavaScriptCore/assembler/MacroAssemblerCodeRef.h (modified) (5 diffs)

trunk/JavaScriptCore/assembler/MacroAssemblerCodeRef.h

@@ -36 +36 @@
 #if ENABLE(ASSEMBLER)
 
+// ASSERT_VALID_CODE_POINTER checks that ptr is a non-null pointer, and that it is a valid
+// instruction address on the platform (for example, check any alignment requirements).
+#if PLATFORM(ARM_V7)
+// ARM/thumb instructions must be 16-bit aligned, but all code pointers to be loaded
+// into the processor are decorated with the bottom bit set, indicating that this is
+// thumb code (as oposed to 32-bit traditional ARM).  The first test checks for both
+// decorated and undectorated null, and the second test ensures that the pointer is
+// decorated.
+#define ASSERT_VALID_CODE_POINTER(ptr) \
+    ASSERT(reinterpret_cast<intptr_t>(ptr) & ~1); \
+    ASSERT(reinterpret_cast<intptr_t>(ptr) & 1)
+#else
+#define ASSERT_VALID_CODE_POINTER(ptr) \
+    ASSERT(ptr)
+#endif
+
 namespace JSC {
 
@@ -53 +69 @@
         : m_value(reinterpret_cast<void*>(value))
     {
-        ASSERT(m_value);
+        ASSERT_VALID_CODE_POINTER(m_value);
     }
 
@@ -80 +96 @@
         : m_value(value)
     {
-        ASSERT(m_value);
+        ASSERT_VALID_CODE_POINTER(m_value);
     }
 
@@ -100 +116 @@
 
     explicit MacroAssemblerCodePtr(void* value)
+#if PLATFORM(ARM_V7)
+        // Decorate the pointer as a thumb code pointer.
+        : m_value(reinterpret_cast<char*>(value) + 1)
+#else
         : m_value(value)
+#endif
     {
-        ASSERT(m_value);
+        ASSERT_VALID_CODE_POINTER(m_value);
     }
 
@@ -108 +129 @@
         : m_value(ra.value())
     {
-        ASSERT(m_value);
+        ASSERT_VALID_CODE_POINTER(m_value);
     }
 
     void* executableAddress() const { return m_value; }
-    void* dataLocation() const { ASSERT(m_value); return m_value; }
+#if PLATFORM(ARM_V7)
+    // To use this pointer as a data address remove the decoration.
+    void* dataLocation() const { ASSERT_VALID_CODE_POINTER(m_value); return reinterpret_cast<char*>(m_value) - 1; }
+#else
+    void* dataLocation() const { ASSERT_VALID_CODE_POINTER(m_value); return m_value; }
+#endif
 
 private: