Author: [email protected]
Date: Tue Mar 3 03:51:59 2009
New Revision: 1403
Modified:
branches/bleeding_edge/src/virtual-frame.cc
Log:
Before emitting code to merge frames, forget the sync flag (telling
that an element is mirrored in memory) for elements whose target is a
register. This avoids generating some duplicate merge blocks.
Review URL: http://codereview.chromium.org/40005
Modified: branches/bleeding_edge/src/virtual-frame.cc
==============================================================================
--- branches/bleeding_edge/src/virtual-frame.cc (original)
+++ branches/bleeding_edge/src/virtual-frame.cc Tue Mar 3 03:51:59 2009
@@ -230,14 +230,19 @@
void VirtualFrame::PrepareMergeTo(VirtualFrame* expected) {
- // No code needs to be generated to invalidate valid elements. No
- // code needs to be generated to move values to memory if they are
- // already synced.
+ // Perform state changes on this frame that will make merge to the
+ // expected frame simpler or else increase the likelihood that his
+ // frame will match another.
for (int i = 0; i < elements_.length(); i++) {
FrameElement source = elements_[i];
FrameElement target = expected->elements_[i];
+
if (!target.is_valid() ||
(target.is_memory() && !source.is_memory() && source.is_synced()))
{
+ // No code needs to be generated to invalidate valid elements.
+ // No code needs to be generated to move values to memory if
+ // they are already synced. We perform those moves here, before
+ // merging.
if (source.is_register()) {
// If the frame is the code generator's current frame, we have
// to decrement both the frame-internal and global register
@@ -249,6 +254,13 @@
}
}
elements_[i] = target;
+ } else if (target.is_register() && !target.is_synced() &&
+ !source.is_memory()) {
+ // If an element's target is a register that doesn't need to be
+ // synced, and the element is not in memory, then the sync state
+ // of the element is irrelevant. We clear the sync bit.
+ ASSERT(source.is_valid());
+ elements_[i].clear_sync();
}
}
}
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