Avoid allocating unnecessary result locations for some instructions.

runtime/vm/intermediate_language_ia32.cc

Index: runtime/vm/intermediate_language_ia32.cc
===================================================================
--- runtime/vm/intermediate_language_ia32.cc	(revision 12100)
+++ runtime/vm/intermediate_language_ia32.cc	(working copy)
@@ -1033,7 +1033,9 @@
   LocationSummary* locs = new LocationSummary(1, 1, LocationSummary::kNoCall);
   locs->set_in(0, Location::RequiresRegister());
   locs->set_temp(0, Location::RequiresRegister());
-  locs->set_out(Location::SameAsFirstInput());
+  locs->set_out(is_used()

[Kevin Millikin (Google), 2012/09/10 12:28:02]

This should be:

locs->set_out(is_used()
                  ? Location::SameAsFirstInput()
                  : Location::NoLocation());

or:

locs->set_out(is_used() ? Location::SameAsFirstInput()
                        : Location::NoLocation());

or:

locs->set_out(
    is_used() ? Location::SameAsFirstInput() : Location::NoLocation());

[Florian Schneider, 2012/09/10 13:05:41]

Done.

+                ? Location::SameAsFirstInput()
+                : Location::NoLocation());
   return locs;
 }
 
@@ -1041,7 +1043,7 @@
 void StoreStaticFieldInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Register value = locs()->in(0).reg();
   Register temp = locs()->temp(0).reg();
-  ASSERT(locs()->out().reg() == value);
+  ASSERT(!is_used() || (locs()->out().reg() == value));
 
   __ LoadObject(temp, field());
   if (this->value()->NeedsStoreBuffer()) {