Changeset 214908 in webkit for trunk/Source/JavaScriptCore/b3/testb3.cpp

Timestamp:

Apr 4, 2017, 3:37:51 PM (8 years ago)

Author:

[email protected]

Message:

B3::LowerToAir incorrectly selects BitXor(AtomicStrongCAS(...), $1)
​https://bugs.webkit.org/show_bug.cgi?id=169867

Reviewed by Saam Barati.

The BitXor(AtomicWeakCAS(...), $1) optimization makes a lot of sense because we an fold the
BitXor into the CAS condition read-out. But there is no version of this that is profitable or
correct for AtomicStrongCAS. The inversion case is handled by Equal(AtomicStrongCAS(...), ...)
becoming NotEqual(AtomicStrongCAS(...), ...), and we alraedy handle that separately.

So, the fix here is to make the BitXor CAS pattern only recognize AtomicWeakCAS.

• b3/B3LowerToAir.cpp:

(JSC::B3::Air::LowerToAir::lower):

• b3/testb3.cpp:

(JSC::B3::testAtomicStrongCAS):

File:

• trunk/Source/JavaScriptCore/b3/testb3.cpp (modified) (1 diff)

trunk/Source/JavaScriptCore/b3/testb3.cpp

@@ -14866 +14866 @@
         value[0] = static_cast<T>(-1);
         CHECK_EQ(invoke<typename NativeTraits<T>::CanonicalType>(*code, value), static_cast<typename NativeTraits<T>::CanonicalType>(static_cast<T>(-1)));
+        CHECK_EQ(value[0], static_cast<T>(-1));
+        CHECK_EQ(value[1], 13);
+        checkMyDisassembly(*code, true);
+    }
+    
+    {
+        // Test for https://bugs.webkit.org/show_bug.cgi?id=169867.
+        
+        Procedure proc;
+        BasicBlock* root = proc.addBlock();
+        root->appendNew<Value>(
+            proc, Return, Origin(),
+            root->appendNew<Value>(
+                proc, BitXor, Origin(),
+                root->appendNew<AtomicValue>(
+                    proc, AtomicStrongCAS, Origin(), width,
+                    root->appendIntConstant(proc, Origin(), type, 42),
+                    root->appendIntConstant(proc, Origin(), type, 0xbeef),
+                    root->appendNew<ArgumentRegValue>(proc, Origin(), GPRInfo::argumentGPR0)),
+                root->appendIntConstant(proc, Origin(), type, 1)));
+        
+        typename NativeTraits<T>::CanonicalType one = 1;
+        
+        auto code = compileProc(proc);
+        T value[2];
+        value[0] = 42;
+        value[1] = 13;
+        CHECK_EQ(invoke<typename NativeTraits<T>::CanonicalType>(*code, value), 42 ^ one);
+        CHECK_EQ(value[0], static_cast<T>(0xbeef));
+        CHECK_EQ(value[1], 13);
+        value[0] = static_cast<T>(300);
+        CHECK_EQ(invoke<typename NativeTraits<T>::CanonicalType>(*code, value), static_cast<typename NativeTraits<T>::CanonicalType>(static_cast<T>(300)) ^ one);
+        CHECK_EQ(value[0], static_cast<T>(300));
+        CHECK_EQ(value[1], 13);
+        value[0] = static_cast<T>(-1);
+        CHECK_EQ(invoke<typename NativeTraits<T>::CanonicalType>(*code, value), static_cast<typename NativeTraits<T>::CanonicalType>(static_cast<T>(-1)) ^ one);
         CHECK_EQ(value[0], static_cast<T>(-1));
         CHECK_EQ(value[1], 13);