FTL should eliminate array bounds checks in loops
https://bugs.webkit.org/show_bug.cgi?id=145768
Reviewed by Benjamin Poulain.
Source/JavaScriptCore:
This adds a phase that does forward propagation of integer inequalities. This allows us
to do the algebraic reasoning we need to eliminate array bounds checks in loops. It
also eliminates overflow checks on ArithAdd with a constant.
The phase's analysis produces results that are powerful enough to do speculative bounds
check hoisting, but this phase currently only does elimination. We can implement
hoisting later.
On programs that just loop over an array like:
for (var i = 0; i < array.length; ++i)
thingy += array[i]
This change is a 60% speed-up.
This is also a ~3% speed-up on Kraken, and it shows various speed-ups on individual
tests in Octane.
* CMakeLists.txt:
* JavaScriptCore.vcxproj/JavaScriptCore.vcxproj:
* JavaScriptCore.xcodeproj/project.pbxproj:
* dfg/DFGIntegerRangeOptimizationPhase.cpp: Added.
(JSC::DFG::performIntegerRangeOptimization):
* dfg/DFGIntegerRangeOptimizationPhase.h: Added.
* dfg/DFGPlan.cpp:
(JSC::DFG::Plan::compileInThreadImpl):
* tests/stress/add-overflows-after-not-equal.js: Added.
* tests/stress/no-abc-skippy-loop.js: Added.
* tests/stress/no-abc-skippy-paired-loop.js: Added.
* tests/stress/sub-overflows-after-not-equal.js: Added.
LayoutTests:
* js/regress/abc-forward-loop-equal-expected.txt: Added.
* js/regress/abc-forward-loop-equal.html: Added.
* js/regress/abc-postfix-backward-loop-expected.txt: Added.
* js/regress/abc-postfix-backward-loop.html: Added.
* js/regress/abc-skippy-loop-expected.txt: Added.
* js/regress/abc-skippy-loop.html: Added.
* js/regress/abc-simple-backward-loop-expected.txt: Added.
* js/regress/abc-simple-backward-loop.html: Added.
* js/regress/abc-simple-forward-loop-expected.txt: Added.
* js/regress/abc-simple-forward-loop.html: Added.
* js/regress/script-tests/abc-forward-loop-equal.js: Added.
* js/regress/script-tests/abc-postfix-backward-loop.js: Added.
* js/regress/script-tests/abc-skippy-loop.js: Added.
* js/regress/script-tests/abc-simple-backward-loop.js: Added.
* js/regress/script-tests/abc-simple-forward-loop.js: Added.
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@185640 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/JavaScriptCore/dfg/DFGIntegerRangeOptimizationPhase.h b/Source/JavaScriptCore/dfg/DFGIntegerRangeOptimizationPhase.h
new file mode 100644
index 0000000..fe0615e
--- /dev/null
+++ b/Source/JavaScriptCore/dfg/DFGIntegerRangeOptimizationPhase.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2015 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef DFGIntegerRangeOptimizationPhase_h
+#define DFGIntegerRangeOptimizationPhase_h
+
+#if ENABLE(DFG_JIT)
+
+namespace JSC { namespace DFG {
+
+class Graph;
+
+// Removes overflow checks and out-of-bounds checks by doing a forward flow analysis to prove
+// inequalities. It will remove the overflow and bounds checks in loops like:
+//
+// for (var i = 0; i < array.length; ++i) array[i];
+
+bool performIntegerRangeOptimization(Graph&);
+
+} } // namespace JSC::DFG
+
+#endif // ENABLE(DFG_JIT)
+
+#endif // DFGIntegerRangeOptimizationPhase_h
+
