Title: [191860] trunk/Source/_javascript_Core
- Revision
- 191860
- Author
- fpi...@apple.com
- Date
- 2015-11-01 11:42:51 -0800 (Sun, 01 Nov 2015)
Log Message
Unreviewed, add a FIXME referencing https://bugs.webkit.org/show_bug.cgi?id=150777.
* b3/B3LowerToAir.cpp:
(JSC::B3::Air::LowerToAir::AddressSelector::acceptRoot):
Modified Paths
Diff
Modified: trunk/Source/_javascript_Core/ChangeLog (191859 => 191860)
--- trunk/Source/_javascript_Core/ChangeLog 2015-11-01 17:22:54 UTC (rev 191859)
+++ trunk/Source/_javascript_Core/ChangeLog 2015-11-01 19:42:51 UTC (rev 191860)
@@ -1,5 +1,12 @@
2015-11-01 Filip Pizlo <fpi...@apple.com>
+ Unreviewed, add a FIXME referencing https://bugs.webkit.org/show_bug.cgi?id=150777.
+
+ * b3/B3LowerToAir.cpp:
+ (JSC::B3::Air::LowerToAir::AddressSelector::acceptRoot):
+
+2015-11-01 Filip Pizlo <fpi...@apple.com>
+
Unreviewed, add a FIXME referencing https://bugs.webkit.org/show_bug.cgi?id=150775.
* b3/B3LowerToAir.cpp:
Modified: trunk/Source/_javascript_Core/b3/B3LowerToAir.cpp (191859 => 191860)
--- trunk/Source/_javascript_Core/b3/B3LowerToAir.cpp 2015-11-01 17:22:54 UTC (rev 191859)
+++ trunk/Source/_javascript_Core/b3/B3LowerToAir.cpp 2015-11-01 19:42:51 UTC (rev 191860)
@@ -400,7 +400,15 @@
{
this->root = root;
// We don't want to match an address _expression_ that has already been computed
- // explicitly.
+ // explicitly. This mostly makes sense. Note that we never hoist basic address
+ // expressions like offset(base), because those are sunk into the MemoryValue. So,
+ // this is mainly just relevant to Index expressions and other more complicated
+ // things. It stands to reason that most of the time, we won't hoist an Index
+ // _expression_. And if we do, then probably it's a good thing to compute it outside
+ // a loop. That being said, this might turn into a problem. For example, it will
+ // require an extra register to be live. That's unlikely to be profitable.
+ // FIXME: Consider matching an address _expression_ even if we've already assigned a
+ // Tmp to it. https://bugs.webkit.org/show_bug.cgi?id=150777
return !lower.valueToTmp[root];
}
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