Changeset 108753 in webkit

Timestamp:

Feb 24, 2012 1:49:38 AM (12 years ago)

Author:

commit-queue@webkit.org

Message:

Remove useless jump instructions for short circuit
​https://bugs.webkit.org/show_bug.cgi?id=75602

Patch by Han Hojong <​hojong.han@samsung.com> on 2012-02-24
Reviewed by Michael Saboff.

Jump instruction is inserted to make short circuit,
however it does nothing but moving to the next instruction.
Therefore useless jump instructions are removed,
and jump list is moved into the case not for a short circuit,
so that only necessary instructions are added to JIT code
unless it has a 16 bit pattern character and an 8 bit string.

• yarr/YarrJIT.cpp:

(JSC::Yarr::YarrGenerator::generatePatternCharacterGreedy):
(JSC::Yarr::YarrGenerator::backtrackPatternCharacterNonGreedy):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• yarr/YarrJIT.cpp (modified) (4 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2012-02-24  Han Hojong  <hojong.han@samsung.com>
+
+        Remove useless jump instructions for short circuit
+        https://bugs.webkit.org/show_bug.cgi?id=75602
+
+        Reviewed by Michael Saboff.
+
+        Jump instruction is inserted to make short circuit, 
+        however it does nothing but moving to the next instruction.
+        Therefore useless jump instructions are removed, 
+        and jump list is moved into the case not for a short circuit,
+        so that only necessary instructions are added to JIT code
+        unless it has a 16 bit pattern character and an 8 bit string.
+
+        * yarr/YarrJIT.cpp:
+        (JSC::Yarr::YarrGenerator::generatePatternCharacterGreedy):
+        (JSC::Yarr::YarrGenerator::backtrackPatternCharacterNonGreedy):
+
 2012-02-24  Sheriff Bot  <webkit.review.bot@gmail.com>
 

trunk/Source/JavaScriptCore/yarr/YarrJIT.cpp

@@ -817 +817 @@
         move(TrustedImm32(0), countRegister);
 
-        if ((ch > 0xff) && (m_charSize == Char8)) {
-            // Have a 16 bit pattern character and an 8 bit string - short circuit
-            op.m_jumps.append(jump());
-        } else {
+        // Unless have a 16 bit pattern character and an 8 bit string - short circuit
+        if (!((ch > 0xff) && (m_charSize == Char8))) {
             JumpList failures;
             Label loop(this);
@@ -838 +836 @@
 
         storeToFrame(countRegister, term->frameLocation);
-
     }
     void backtrackPatternCharacterGreedy(size_t opIndex)
@@ -876 +873 @@
         const RegisterID countRegister = regT1;
 
-        JumpList nonGreedyFailures;
-
         m_backtrackingState.link(this);
 
         loadFromFrame(term->frameLocation, countRegister);
 
-        if ((ch > 0xff) && (m_charSize == Char8)) {
-            // Have a 16 bit pattern character and an 8 bit string - short circuit
-            nonGreedyFailures.append(jump());
-        } else {
+        // Unless have a 16 bit pattern character and an 8 bit string - short circuit
+        if (!((ch > 0xff) && (m_charSize == Char8))) {
+            JumpList nonGreedyFailures;
             nonGreedyFailures.append(atEndOfInput());
             if (term->quantityCount != quantifyInfinite)
@@ -895 +889 @@
 
             jump(op.m_reentry);
-        }
-        nonGreedyFailures.link(this);
+            nonGreedyFailures.link(this);
+        }
 
         sub32(countRegister, index);