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diff src/share/vm/opto/lcm.cpp @ 642:660978a2a31a

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6791178: Specialize for zero as the compressed oop vm heap base Summary: Use zero based compressed oops if java heap is below 32gb and unscaled compressed oops if java heap is below 4gb. Reviewed-by: never, twisti, jcoomes, coleenp
author kvn
date Thu, 12 Mar 2009 10:37:46 -0700
parents 3b5ac9e7e6ea
children bd441136a5ce
line wrap: on
line diff
--- a/src/share/vm/opto/lcm.cpp	Wed Mar 11 14:16:13 2009 -0700
+++ b/src/share/vm/opto/lcm.cpp	Thu Mar 12 10:37:46 2009 -0700
@@ -158,7 +158,14 @@
           continue;             // Give up if offset is beyond page size
         // cannot reason about it; is probably not implicit null exception
       } else {
-        const TypePtr* tptr = base->bottom_type()->is_ptr();
+        const TypePtr* tptr;
+        if (UseCompressedOops && Universe::narrow_oop_shift() == 0) {
+          // 32-bits narrow oop can be the base of address expressions
+          tptr = base->bottom_type()->make_ptr();
+        } else {
+          // only regular oops are expected here
+          tptr = base->bottom_type()->is_ptr();
+        }
         // Give up if offset is not a compile-time constant
         if( offset == Type::OffsetBot || tptr->_offset == Type::OffsetBot )
           continue;