Changeset 91678 in webkit

Timestamp:

Jul 25, 2011, 10:59:08 AM (14 years ago)

Author:

commit-queue@webkit.org

Message:

X86-64 assembler emits three instructions instead of two for certain
loads and stores.
​https://bugs.webkit.org/show_bug.cgi?id=65095

Patch by Filip Pizlo <​fpizlo@apple.com> on 2011-07-25
Reviewed by Gavin Barraclough.

Simply made these four methods in the assembler use the scratch register,
which they were previously avoiding. It still optimizes for the case where
an absolute address memory accesses is using EAX. This results in a slight
performance improvement.

• assembler/MacroAssemblerX86_64.h:

(JSC::MacroAssemblerX86_64::load32):
(JSC::MacroAssemblerX86_64::store32):
(JSC::MacroAssemblerX86_64::loadPtr):
(JSC::MacroAssemblerX86_64::storePtr):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• assembler/MacroAssemblerX86_64.h (modified) (4 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2011-07-25  Filip Pizlo  <fpizlo@apple.com>
+
+        X86-64 assembler emits three instructions instead of two for certain
+        loads and stores.
+        https://bugs.webkit.org/show_bug.cgi?id=65095
+
+        Reviewed by Gavin Barraclough.
+        
+        Simply made these four methods in the assembler use the scratch register,
+        which they were previously avoiding.  It still optimizes for the case where
+        an absolute address memory accesses is using EAX.  This results in a slight
+        performance improvement.
+
+        * assembler/MacroAssemblerX86_64.h:
+        (JSC::MacroAssemblerX86_64::load32):
+        (JSC::MacroAssemblerX86_64::store32):
+        (JSC::MacroAssemblerX86_64::loadPtr):
+        (JSC::MacroAssemblerX86_64::storePtr):
+
 2011-07-25  Ryuan Choi  <ryuan.choi@samsung.com>
 

trunk/Source/JavaScriptCore/assembler/MacroAssemblerX86_64.h

@@ -82 +82 @@
             m_assembler.movl_mEAX(address);
         else {
-            move(X86Registers::eax, dest);
-            m_assembler.movl_mEAX(address);
-            swap(X86Registers::eax, dest);
+            move(TrustedImmPtr(address), dest);
+            load32(dest, dest);
         }
     }
@@ -108 +107 @@
     void store32(TrustedImm32 imm, void* address)
     {
-        move(X86Registers::eax, scratchRegister);
-        move(imm, X86Registers::eax);
-        m_assembler.movl_EAXm(address);
-        move(scratchRegister, X86Registers::eax);
+        move(TrustedImmPtr(address), scratchRegister);
+        store32(imm, scratchRegister);
     }
 
@@ -258 +255 @@
             m_assembler.movq_mEAX(address);
         else {
-            move(X86Registers::eax, dest);
-            m_assembler.movq_mEAX(address);
-            swap(X86Registers::eax, dest);
+            move(TrustedImmPtr(address), dest);
+            loadPtr(dest, dest);
         }
     }
@@ -291 +287 @@
             m_assembler.movq_EAXm(address);
         else {
-            swap(X86Registers::eax, src);
-            m_assembler.movq_EAXm(address);
-            swap(X86Registers::eax, src);
+            move(TrustedImmPtr(address), scratchRegister);
+            storePtr(src, scratchRegister);
         }
     }