Changeset 197685 in webkit

Timestamp:

Mar 7, 2016, 10:23:46 AM (11 years ago)

Author:

benjamin@webkit.org

Message:

[JSC] Remove a useless "Move" from baseline-JIT op_mul's fast path
​https://bugs.webkit.org/show_bug.cgi?id=155071

Reviewed by Geoffrey Garen.

We do not need to multiply to a scratch and then move the result
to the destination. We can just multiply to the destination.

• jit/JITArithmetic.cpp:

(JSC::JIT::emit_op_mul):

• jit/JITMulGenerator.cpp:

(JSC::JITMulGenerator::generateFastPath):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• jit/JITArithmetic.cpp (modified) (1 diff)
• jit/JITMulGenerator.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2016-03-07  Benjamin Poulain  <benjamin@webkit.org>
+
+        [JSC] Remove a useless "Move" from baseline-JIT op_mul's fast path
+        https://bugs.webkit.org/show_bug.cgi?id=155071
+
+        Reviewed by Geoffrey Garen.
+
+        We do not need to multiply to a scratch and then move the result
+        to the destination. We can just multiply to the destination.
+
+        * jit/JITArithmetic.cpp:
+        (JSC::JIT::emit_op_mul):
+        * jit/JITMulGenerator.cpp:
+        (JSC::JITMulGenerator::generateFastPath):
+
 2016-03-07  Yusuke Suzuki  <utatane.tea@gmail.com>
 

trunk/Source/JavaScriptCore/jit/JITArithmetic.cpp

@@ -823 +823 @@
     JSValueRegs leftRegs = JSValueRegs(regT0);
     JSValueRegs rightRegs = JSValueRegs(regT1);
-    JSValueRegs resultRegs = leftRegs;
-    GPRReg scratchGPR = regT2;
+    JSValueRegs resultRegs = JSValueRegs(regT2);
+    GPRReg scratchGPR = regT3;
     FPRReg scratchFPR = InvalidFPRReg;
 #else

trunk/Source/JavaScriptCore/jit/JITMulGenerator.cpp

@@ -61 +61 @@
         CCallHelpers::Jump notInt32 = jit.branchIfNotInt32(var);
 
-        m_slowPathJumpList.append(jit.branchMul32(CCallHelpers::Overflow, var.payloadGPR(), CCallHelpers::Imm32(constOpr.asConstInt32()), m_scratchGPR));
+        GPRReg multiplyResultGPR = m_result.payloadGPR();
+        if (multiplyResultGPR == var.payloadGPR())
+            multiplyResultGPR = m_scratchGPR;
 
-        jit.boxInt32(m_scratchGPR, m_result);
+        m_slowPathJumpList.append(jit.branchMul32(CCallHelpers::Overflow, var.payloadGPR(), CCallHelpers::Imm32(constOpr.asConstInt32()), multiplyResultGPR));
+
+        jit.boxInt32(multiplyResultGPR, m_result);
         m_endJumpList.append(jit.jump());