Changeset 37405 in webkit for trunk/JavaScriptCore/VM/CTI.cpp

Timestamp:

Oct 7, 2008, 8:46:34 PM (17 years ago)

Author:

[email protected]

Message:

2008-10-07 Maciej Stachowiak <​[email protected]>

Reviewed by Mark Rowe.

• optimize away multiplication by constant 1.0

2.3% speedup on v8 RayTrace benchmark

Apparently it's not uncommon for JavaScript code to multiply by
constant 1.0 in the mistaken belief that this converts integer to
floating point and that there is any operational difference.

• VM/CTI.cpp: (JSC::CTI::privateCompileMainPass): Optimize to_jsnumber for case where parameter is already number. (JSC::CTI::privateCompileSlowCases): ditto
• VM/Machine.cpp: (JSC::Machine::privateExecute): ditto
• kjs/grammar.y: (makeMultNode): Transform as follows: +FOO * BAR ==> FOO * BAR FOO * +BAR ==> FOO * BAR FOO * 1 ==> +FOO 1 * FOO ==> +FOO (makeDivNode): Transform as follows: +FOO / BAR ==> FOO / BAR FOO / +BAR ==> FOO / BAR (makeSubNode): Transform as follows: +FOO - BAR ==> FOO - BAR FOO - +BAR ==> FOO - BAR
• kjs/nodes.h: (JSC::ExpressionNode::stripUnaryPlus): Helper for above grammar.y changes (JSC::UnaryPlusNode::stripUnaryPlus): ditto

File:

• trunk/JavaScriptCore/VM/CTI.cpp (modified) (2 diffs)

trunk/JavaScriptCore/VM/CTI.cpp

@@ -1768 +1768 @@
         }
         case op_to_jsnumber: {
-            emitGetPutArg(instruction[i + 2].u.operand, 0, X86::ecx);
-            emitCall(i, Machine::cti_op_to_jsnumber);
+            emitGetArg(instruction[i + 2].u.operand, X86::eax);
+            
+            m_jit.testl_i32r(JSImmediate::TagBitTypeInteger, X86::eax);
+            X86Assembler::JmpSrc wasImmediate = m_jit.emitUnlinkedJnz();
+
+            m_jit.movl_mr(OBJECT_OFFSET(JSCell, m_structureID), X86::eax, X86::ecx);
+            m_jit.cmpl_i32m(NumberType, OBJECT_OFFSET(StructureID, m_typeInfo.m_type), X86::ecx);
+            
+            m_slowCases.append(SlowCaseEntry(m_jit.emitUnlinkedJne(), i));
+            
+            m_jit.link(wasImmediate, m_jit.label());
+
             emitPutResult(instruction[i + 1].u.operand);
             i += 3;
@@ -2519 +2529 @@
             break;
         }
+        case op_to_jsnumber: {
+            m_jit.link(iter->from, m_jit.label());
+
+            emitPutArg(X86::eax, 0);
+            emitCall(i, Machine::cti_op_to_jsnumber);
+
+            emitPutResult(instruction[i + 1].u.operand);
+            i += 3;
+            break;
+        }
 
         default: