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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/195637">195637</a></dd>
<dt>Author</dt> <dd>fpizlo@apple.com</dd>
<dt>Date</dt> <dd>2016-01-26 16:49:03 -0800 (Tue, 26 Jan 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>B3's integer range analysis should know that Mul'ing two sufficiently small numbers will yield a number that still has a meaningful range
https://bugs.webkit.org/show_bug.cgi?id=153518
Reviewed by Benjamin Poulain.
Octane/encrypt had an addition overflow check that can be proved away by being sufficiently
sneaky about the analysis of adds, multiplies, and shifts.
I almost added these optimizations to the DFG integer range optimization phase. That phase is
very complicated. B3's integer range analysis is trivial. So I added it to B3. Eventually
we'll want this same machinery in the DFG also.
8% speed-up on Octane/encrypt.
* b3/B3ReduceStrength.cpp:
* b3/B3Value.cpp:
(JSC::B3::Value::dump): Dumping a constant value's name now dumps its value. This makes a huge difference for reading IR.
(JSC::B3::Value::cloneImpl):
(JSC::B3::Value::deepDump):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreb3B3ReduceStrengthcpp">trunk/Source/JavaScriptCore/b3/B3ReduceStrength.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoreb3B3Valuecpp">trunk/Source/JavaScriptCore/b3/B3Value.cpp</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (195636 => 195637)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2016-01-27 00:33:33 UTC (rev 195636)
+++ trunk/Source/JavaScriptCore/ChangeLog 2016-01-27 00:49:03 UTC (rev 195637)
</span><span class="lines">@@ -1,5 +1,27 @@
</span><span class="cx"> 2016-01-26 Filip Pizlo <fpizlo@apple.com>
</span><span class="cx">
</span><ins>+ B3's integer range analysis should know that Mul'ing two sufficiently small numbers will yield a number that still has a meaningful range
+ https://bugs.webkit.org/show_bug.cgi?id=153518
+
+ Reviewed by Benjamin Poulain.
+
+ Octane/encrypt had an addition overflow check that can be proved away by being sufficiently
+ sneaky about the analysis of adds, multiplies, and shifts.
+
+ I almost added these optimizations to the DFG integer range optimization phase. That phase is
+ very complicated. B3's integer range analysis is trivial. So I added it to B3. Eventually
+ we'll want this same machinery in the DFG also.
+
+ 8% speed-up on Octane/encrypt.
+
+ * b3/B3ReduceStrength.cpp:
+ * b3/B3Value.cpp:
+ (JSC::B3::Value::dump): Dumping a constant value's name now dumps its value. This makes a huge difference for reading IR.
+ (JSC::B3::Value::cloneImpl):
+ (JSC::B3::Value::deepDump):
+
+2016-01-26 Filip Pizlo <fpizlo@apple.com>
+
</ins><span class="cx"> It should be possible to disable FTL for a range like we disable DFG for a range
</span><span class="cx"> https://bugs.webkit.org/show_bug.cgi?id=153511
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreb3B3ReduceStrengthcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/b3/B3ReduceStrength.cpp (195636 => 195637)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/b3/B3ReduceStrength.cpp 2016-01-27 00:33:33 UTC (rev 195636)
+++ trunk/Source/JavaScriptCore/b3/B3ReduceStrength.cpp 2016-01-27 00:49:03 UTC (rev 195637)
</span><span class="lines">@@ -252,6 +252,102 @@
</span><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+ template<typename T>
+ IntRange shl(int32_t shiftAmount)
+ {
+ T newMin = static_cast<T>(m_min) << shiftAmount;
+ T newMax = static_cast<T>(m_max) << shiftAmount;
+
+ if ((newMin >> shiftAmount) != static_cast<T>(m_min))
+ newMin = std::numeric_limits<T>::min();
+ if ((newMax >> shiftAmount) != static_cast<T>(m_max))
+ newMax = std::numeric_limits<T>::max();
+
+ return IntRange(newMin, newMax);
+ }
+
+ IntRange shl(int32_t shiftAmount, Type type)
+ {
+ switch (type) {
+ case Int32:
+ return shl<int32_t>(shiftAmount);
+ case Int64:
+ return shl<int64_t>(shiftAmount);
+ default:
+ RELEASE_ASSERT_NOT_REACHED();
+ return IntRange();
+ }
+ }
+
+ template<typename T>
+ IntRange add(const IntRange& other)
+ {
+ if (couldOverflowAdd<T>(other))
+ return top<T>();
+ return IntRange(m_min + other.m_min, m_max + other.m_max);
+ }
+
+ IntRange add(const IntRange& other, Type type)
+ {
+ switch (type) {
+ case Int32:
+ return add<int32_t>(other);
+ case Int64:
+ return add<int64_t>(other);
+ default:
+ RELEASE_ASSERT_NOT_REACHED();
+ return IntRange();
+ }
+ }
+
+ template<typename T>
+ IntRange sub(const IntRange& other)
+ {
+ if (couldOverflowSub<T>(other))
+ return top<T>();
+ return IntRange(m_min - other.m_max, m_max - other.m_min);
+ }
+
+ IntRange sub(const IntRange& other, Type type)
+ {
+ switch (type) {
+ case Int32:
+ return sub<int32_t>(other);
+ case Int64:
+ return sub<int64_t>(other);
+ default:
+ RELEASE_ASSERT_NOT_REACHED();
+ return IntRange();
+ }
+ }
+
+ template<typename T>
+ IntRange mul(const IntRange& other)
+ {
+ if (couldOverflowMul<T>(other))
+ return top<T>();
+ return IntRange(
+ std::min(
+ std::min(m_min * other.m_min, m_min * other.m_max),
+ std::min(m_max * other.m_min, m_max * other.m_max)),
+ std::max(
+ std::max(m_min * other.m_min, m_min * other.m_max),
+ std::max(m_max * other.m_min, m_max * other.m_max)));
+ }
+
+ IntRange mul(const IntRange& other, Type type)
+ {
+ switch (type) {
+ case Int32:
+ return mul<int32_t>(other);
+ case Int64:
+ return mul<int64_t>(other);
+ default:
+ RELEASE_ASSERT_NOT_REACHED();
+ return IntRange();
+ }
+ }
+
</ins><span class="cx"> private:
</span><span class="cx"> int64_t m_min { 0 };
</span><span class="cx"> int64_t m_max { 0 };
</span><span class="lines">@@ -1839,8 +1935,13 @@
</span><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span><del>- IntRange rangeFor(Value* value)
</del><ins>+ // FIXME: This should really be a forward analysis. Instead, we uses a bounded-search backwards
+ // analysis.
+ IntRange rangeFor(Value* value, unsigned timeToLive = 5)
</ins><span class="cx"> {
</span><ins>+ if (!timeToLive)
+ return IntRange::top(value->type());
+
</ins><span class="cx"> switch (value->opcode()) {
</span><span class="cx"> case Const32:
</span><span class="cx"> case Const64: {
</span><span class="lines">@@ -1863,6 +1964,24 @@
</span><span class="cx"> return IntRange::rangeForZShr(value->child(1)->asInt32(), value->type());
</span><span class="cx"> break;
</span><span class="cx">
</span><ins>+ case Shl:
+ if (value->child(1)->hasInt32())
+ return rangeFor(value->child(0), timeToLive - 1).shl(
+ value->child(1)->asInt32(), value->type());
+ break;
+
+ case Add:
+ return rangeFor(value->child(0), timeToLive - 1).add(
+ rangeFor(value->child(1), timeToLive - 1), value->type());
+
+ case Sub:
+ return rangeFor(value->child(0), timeToLive - 1).sub(
+ rangeFor(value->child(1), timeToLive - 1), value->type());
+
+ case Mul:
+ return rangeFor(value->child(0), timeToLive - 1).mul(
+ rangeFor(value->child(1), timeToLive - 1), value->type());
+
</ins><span class="cx"> default:
</span><span class="cx"> break;
</span><span class="cx"> }
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreb3B3Valuecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/b3/B3Value.cpp (195636 => 195637)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/b3/B3Value.cpp 2016-01-27 00:33:33 UTC (rev 195636)
+++ trunk/Source/JavaScriptCore/b3/B3Value.cpp 2016-01-27 00:49:03 UTC (rev 195637)
</span><span class="lines">@@ -111,7 +111,33 @@
</span><span class="cx">
</span><span class="cx"> void Value::dump(PrintStream& out) const
</span><span class="cx"> {
</span><ins>+ bool isConstant = false;
+
+ switch (m_opcode) {
+ case Const32:
+ out.print("$", asInt32(), "(");
+ isConstant = true;
+ break;
+ case Const64:
+ out.print("$", asInt64(), "(");
+ isConstant = true;
+ break;
+ case ConstFloat:
+ out.print("$", asFloat(), "(");
+ isConstant = true;
+ break;
+ case ConstDouble:
+ out.print("$", asDouble(), "(");
+ isConstant = true;
+ break;
+ default:
+ break;
+ }
+
</ins><span class="cx"> out.print(dumpPrefix, m_index);
</span><ins>+
+ if (isConstant)
+ out.print(")");
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> Value* Value::cloneImpl() const
</span><span class="lines">@@ -127,7 +153,7 @@
</span><span class="cx">
</span><span class="cx"> void Value::deepDump(const Procedure* proc, PrintStream& out) const
</span><span class="cx"> {
</span><del>- out.print(m_type, " ", *this, " = ", m_opcode);
</del><ins>+ out.print(m_type, " ", dumpPrefix, m_index, " = ", m_opcode);
</ins><span class="cx">
</span><span class="cx"> out.print("(");
</span><span class="cx"> CommaPrinter comma;
</span></span></pre>
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