EVALUATION

Tom wrote this to the mailing list:

I looked into this a bit since it's the only thing blocking us pushing  
to hotspot/hotspot.  It's a problem with the support for $ 
$FloatRegister on sparc.  assembler_sparc does weird stuff with  
FloatRegister to deal with the encoding of the double registers above  
31 and that interacts badly with the way $$FloatRegister is  
implemented.  A loadConP has been assigned to D48, which would  
normally be constructed by the as_FloatRegister(48).  When it's  
actually used, it will be converted to a DoubleFloatRegister which  
will convert it into it's actual encoding as 17.  The adlc nows that  
D48 is actually encoded as 17 so it directly constructs a  
FloatRegister with an encoding of 17.  When we go to use it we die  
because double registers have even logical numbers.  So the quick fix  
is to use one of the other conversion idioms like  
as_DoubleFloatRegister($dst$$reg) to construct the register.  We'll  
need to address the implementation of $$FloatRegister separately.
                                     

SUGGESTED FIX

diff -r 9c6be3edf0dc src/cpu/sparc/vm/sparc.ad
--- a/src/cpu/sparc/vm/sparc.ad
+++ b/src/cpu/sparc/vm/sparc.ad
@@ -2794,7 +2794,9 @@ enc_class Fast_Unlock(iRegP oop, iRegP b
     AddressLiteral addrlit(double_address, rspec);
 
     __ sethi(addrlit, $tmp$$Register);
-    __ ldf(FloatRegisterImpl::D, $tmp$$Register, addrlit.low10(), $dst$$FloatRegister, rspec);
+    // XXX This is a quick fix for 6833573.
+    //__ ldf(FloatRegisterImpl::D, $tmp$$Register, addrlit.low10(), $dst$$FloatRegister, rspec);
+    __ ldf(FloatRegisterImpl::D, $tmp$$Register, addrlit.low10(), as_DoubleFloatRegister($dst$$reg), rspec);
   %}
 
   // Compiler ensures base is doubleword aligned and cnt is count of doublewords
@@ -5902,7 +5904,9 @@ instruct loadConD(regD dst, immD src, o7
     AddressLiteral addrlit(double_address, rspec);
 
     __ sethi(addrlit, $tmp$$Register);
-    __ ldf(FloatRegisterImpl::D, $tmp$$Register, addrlit.low10(), $dst$$FloatRegister, rspec);
+    // XXX This is a quick fix for 6833573.
+    //__ ldf(FloatRegisterImpl::D, $tmp$$Register, addrlit.low10(), $dst$$FloatRegister, rspec);
+    __ ldf(FloatRegisterImpl::D, $tmp$$Register, addrlit.low10(), as_DoubleFloatRegister($dst$$reg), rspec);
   %}
   ins_pipe(loadConFD);
 %}