Changeset 108753 in webkit for trunk/Source/JavaScriptCore/yarr

Timestamp:

Feb 24, 2012, 1:49:38 AM (13 years ago)

Author:

[email protected]

Message:

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

Patch by Han Hojong <​[email protected]> 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):

File:

• trunk/Source/JavaScriptCore/yarr/YarrJIT.cpp (modified) (4 diffs)

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);