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			68 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			68 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
| // Copyright 2012 the V8 project authors. All rights reserved.
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| // Redistribution and use in source and binary forms, with or without
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| // modification, are permitted provided that the following conditions are
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| // met:
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| //
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| //     * Redistributions of source code must retain the above copyright
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| //       notice, this list of conditions and the following disclaimer.
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| //     * Redistributions in binary form must reproduce the above
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| //       copyright notice, this list of conditions and the following
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| //       disclaimer in the documentation and/or other materials provided
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| //       with the distribution.
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| //     * Neither the name of Google Inc. nor the names of its
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| //       contributors may be used to endorse or promote products derived
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| //       from this software without specific prior written permission.
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| //
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| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 
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| // Flags: --allow-natives-syntax --opt
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| 
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| // The original problem from the bug: In the example below SMI check for b
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| // generated for inlining of equals invocation (marked with (*)) will be hoisted
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| // out of the loop across the typeof b === "object" condition and cause an
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| // immediate deopt. Another problem here is that no matter how many time we
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| // deopt and reopt we will continue to produce the wrong code.
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| //
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| // The fix is to notice when a deopt and subsequent reopt doesn't find
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| // additional type information, indicating that optimistic LICM should be
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| // disabled during compilation.
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| 
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| function eq(a, b) {
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|   if (typeof b === "object") {
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|     return b.equals(a);  // (*)
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|   }
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|   return a === b;
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| }
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| 
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| Object.prototype.equals = function (other) {
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|   return (this === other);
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| };
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| 
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| function test() {
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|   for (var i = 0; !eq(i, 10); i++)
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|     ;
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| }
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| 
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| eq({}, {});
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| eq({}, {});
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| eq(1, 1);
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| eq(1, 1);
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| test();
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| %OptimizeFunctionOnNextCall(test);
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| test();
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| %OptimizeFunctionOnNextCall(test);
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| // Second compilation should have noticed that LICM wasn't a good idea, and now
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| // function should no longer deopt when called.
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| test();
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| assertOptimized(test);
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