Changeset 36695 in webkit for trunk/JavaScriptCore/VM/CTI.cpp

Timestamp:

Sep 19, 2008, 8:00:43 PM (17 years ago)

Author:

[email protected]

Message:

Improve peformance of local variable initialisation.

Reviewed by Maciej Stachowiak

Pull local and constant initialisation out of slideRegisterWindowForCall
and into its own opcode. This allows the JIT to generate the initialisation
code for a function directly into the instruction stream and so avoids a few
branches on function entry.

Results a 1% progression in SunSpider, particularly in a number of the bitop
tests where the called functions are very fast.

File:

• trunk/JavaScriptCore/VM/CTI.cpp (modified) (3 diffs)

trunk/JavaScriptCore/VM/CTI.cpp

@@ -178 +178 @@
 {
     m_jit.movl_rm(from, dst * sizeof(Register), X86::edi);
+    // FIXME: #ifndef NDEBUG, Write the correct m_type to the register.
+}
+
+ALWAYS_INLINE void CTI::emitInitialiseRegister(unsigned dst)
+{
+    m_jit.movl_i32m(reinterpret_cast<unsigned>(jsUndefined()), dst * sizeof(Register), X86::edi);
     // FIXME: #ifndef NDEBUG, Write the correct m_type to the register.
 }
@@ -526 +532 @@
 void CTI::privateCompileMainPass()
 {
+    if (m_codeBlock->codeType == FunctionCode) {
+        for (int i = -m_codeBlock->numVars; i < 0; i++)
+            emitInitialiseRegister(i);
+    }
+    for (size_t i = 0; i < m_codeBlock->constantRegisters.size(); ++i)
+        emitInitialiseRegister(i);
+
     Instruction* instruction = m_codeBlock->instructions.begin();
     unsigned instructionCount = m_codeBlock->instructions.size();
@@ -1522 +1535 @@
             break;
         }
+        case op_initialise_locals: {
+            i++;
+            break;
+        }
         case op_get_array_length:
         case op_get_by_id_chain: