CTX and TMP registers may not be allocated.

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
===================================================================
--- runtime/vm/intermediate_language_x64.cc	(revision 7882)
+++ runtime/vm/intermediate_language_x64.cc	(working copy)
@@ -58,14 +58,13 @@
 
 LocationSummary* StoreContextComp::MakeLocationSummary() {
   LocationSummary* summary = new LocationSummary(1);
-  summary->set_in(0, Location::RegisterLocation(CTX));

[Vyacheslav Egorov (Google), 2012/05/22 23:25:23]

I don't think this change is necessary. 

This is not a register allocated register, this is known fixed register.

[srdjan, 2012/05/22 23:45:38]

How is it known? The register allocator attempts to allocate any register,
including the one holding context, unless we block it from being allocatable.

[srdjan, 2012/05/22 23:57:21]

Discussed offline and  reverted the changes here by moving the blocking of
registers after the input registers locking and before allocating a register.

+  summary->set_in(0, Location::RequiresRegister());
   return summary;
 }
 
 
 void StoreContextComp::EmitNativeCode(FlowGraphCompiler* compiler) {
-  // Nothing to do.  Context register were loaded by register allocator.
-  ASSERT(locs()->in(0).reg() == CTX);

[Vyacheslav Egorov (Google), 2012/05/22 23:25:23]

Ditto.

+  __ movq(CTX, locs()->in(0).reg());
 }