Workaround for Issue 7250540

There's a problem (originating with Dalvik's failure to properly type constants) with
Dalvik vregs that are used in both reference and floating point situations.  In
particular, if a constant zero is used in a floating point context, the verifier in
some cases will treat it as a null pointer for the purposes generating the GC map.

If that vreg ends up promoted to a floating point value, the run-time value of that
vreg will not be found during garbage collection.  As a quick workaround, this
CL causes the compiler to detect this special case of an immediate zero being loaded
into a promoted floating point register and also store a zero in the core/ref identity
of that vreg.

Note, the CL also excludes references from store elimination.

Change-Id: I72f0a96744823ff9c5a2bd961a5e39ac4bbc707b
diff --git a/src/compiler/codegen/codegen.h b/src/compiler/codegen/codegen.h
index 9dfa609..0698156 100644
--- a/src/compiler/codegen/codegen.h
+++ b/src/compiler/codegen/codegen.h
@@ -381,6 +381,9 @@
     virtual void OpRegCopyWide(CompilationUnit* cu, int dest_lo, int dest_hi, int src_lo,
                                int src_hi) = 0;
     virtual void OpTlsCmp(CompilationUnit* cu, int offset, int val) = 0;
+
+    // Temp workaround
+    void Workaround7250540(CompilationUnit* cu, RegLocation rl_dest, int value);
     };  // Class Codegen
 
 }  // namespace art