Changeset 44838 in webkit for trunk/JavaScriptCore/jit

Timestamp:

Jun 18, 2009, 7:32:29 PM (16 years ago)

Author:

[email protected]

Message:

2009-06-18 Gavin Barraclough <​[email protected]>

Rubber Stamped by Mark Rowe (originally reviewed by Sam Weinig).

(Reintroducing patch added in r44492, and reverted in r44796.)

Change the implementation of op_throw so the stub function always modifies its
return address - if it doesn't find a 'catch' it will switch to a trampoline
to force a return from JIT execution. This saves memory, by avoiding the need
for a unique return for every op_throw.

• jit/JITOpcodes.cpp: (JSC::JIT::emit_op_throw):

JITStubs::cti_op_throw now always changes its return address,
remove return code generated after the stub call (this is now
handled by ctiOpThrowNotCaught).

• jit/JITStubs.cpp: (JSC::):

Add ctiOpThrowNotCaught definitions.

(JSC::JITStubs::DEFINE_STUB_FUNCTION):

Change cti_op_throw to always change its return address.

• jit/JITStubs.h:

Add ctiOpThrowNotCaught declaration.

Location:

trunk/JavaScriptCore/jit

Files:

• JITOpcodes.cpp (modified) (1 diff)
• JITStubs.cpp (modified) (9 diffs)
• JITStubs.h (modified) (1 diff)

trunk/JavaScriptCore/jit/JITOpcodes.cpp

@@ -623 +623 @@
     stubCall.call();
     ASSERT(regT0 == returnValueRegister);
-#if PLATFORM(X86_64)
-    addPtr(Imm32(0x48), X86::esp);
-    pop(X86::ebx);
-    pop(X86::r15);
-    pop(X86::r14);
-    pop(X86::r13);
-    pop(X86::r12);
-    pop(X86::ebp);
-    ret();
-#else
-    addPtr(Imm32(0x1c), X86::esp);
-    pop(X86::ebx);
-    pop(X86::edi);
-    pop(X86::esi);
-    pop(X86::ebp);
-    ret();
+#ifndef NDEBUG
+    // cti_op_throw always changes it's return address,
+    // this point in the code should never be reached.
+    breakpoint();
 #endif
 }

trunk/JavaScriptCore/jit/JITStubs.cpp

@@ -78 +78 @@
 COMPILE_ASSERT(offsetof(struct JITStackFrame, savedEBX) == 0x1c, JITStackFrame_stub_argument_space_matches_ctiTrampoline);
 
-asm(
+asm volatile (
 ".globl " SYMBOL_STRING(ctiTrampoline) "\n"
 SYMBOL_STRING(ctiTrampoline) ":" "\n"
@@ -98 +98 @@
 );
 
-asm(
+asm volatile (
 ".globl " SYMBOL_STRING(ctiVMThrowTrampoline) "\n"
 SYMBOL_STRING(ctiVMThrowTrampoline) ":" "\n"
@@ -113 +113 @@
 );
     
+asm volatile (
+".globl " SYMBOL_STRING(ctiOpThrowNotCaught) "\n"
+SYMBOL_STRING(ctiOpThrowNotCaught) ":" "\n"
+    "addl $0x1c, %esp" "\n"
+    "popl %ebx" "\n"
+    "popl %edi" "\n"
+    "popl %esi" "\n"
+    "popl %ebp" "\n"
+    "ret" "\n"
+);
+    
 #elif COMPILER(GCC) && PLATFORM(X86_64)
 
@@ -125 +136 @@
 COMPILE_ASSERT(offsetof(struct JITStackFrame, savedRBX) == 0x48, JITStackFrame_stub_argument_space_matches_ctiTrampoline);
 
-asm(
+asm volatile (
 ".globl " SYMBOL_STRING(ctiTrampoline) "\n"
 SYMBOL_STRING(ctiTrampoline) ":" "\n"
@@ -151 +162 @@
 );
 
-asm(
+asm volatile (
 ".globl " SYMBOL_STRING(ctiVMThrowTrampoline) "\n"
 SYMBOL_STRING(ctiVMThrowTrampoline) ":" "\n"
@@ -166 +177 @@
 );
 
+asm volatile (
+".globl " SYMBOL_STRING(ctiOpThrowNotCaught) "\n"
+SYMBOL_STRING(ctiOpThrowNotCaught) ":" "\n"
+    "addq $0x48, %rsp" "\n"
+    "popq %rbx" "\n"
+    "popq %r15" "\n"
+    "popq %r14" "\n"
+    "popq %r13" "\n"
+    "popq %r12" "\n"
+    "popq %rbp" "\n"
+    "ret" "\n"
+);
+
 #elif COMPILER(GCC) && PLATFORM(ARM_V7)
 
@@ -183 +207 @@
 COMPILE_ASSERT(offsetof(struct JITStackFrame, enabledProfilerReference) == 0x3c, JITStackFrame_enabledProfilerReference_offset_matches_ctiTrampoline);
 
-asm volatile  (
+asm volatile (
 ".text" "\n"
 ".align 2" "\n"
@@ -290 +314 @@
         }
     }
+     
+     __declspec(naked) void ctiOpThrowNotCaught()
+     {
+         __asm {
+             add esp, 0x1c;
+             pop ebx;
+             pop edi;
+             pop esi;
+             pop ebp;
+             ret;
+         }
+     }
 }
 
@@ -2313 +2349 @@
     if (!handler) {
         *stackFrame.exception = exceptionValue;
+        STUB_SET_RETURN_ADDRESS(reinterpret_cast<void*>(ctiOpThrowNotCaught));
         return JSValue::encode(jsNull());
     }

trunk/JavaScriptCore/jit/JITStubs.h

@@ -183 +183 @@
 
     extern "C" void ctiVMThrowTrampoline();
+    extern "C" void ctiOpThrowNotCaught();
     extern "C" EncodedJSValue ctiTrampoline(
 #if PLATFORM(X86_64)