Hi, Could a gate keeper review the patch for 830? Thank you very much. The original patch exposed a performance degradation due to the instruction size for movl and movq is different. If the constant is not negative and less than 2^31, it's fine to use movl. So that we can save 1 byte here.
Here is the patch:
Index: osprey/be/opt/opt_htable.cxx
===================================================================
--- osprey/be/opt/opt_htable.cxx (revision 3855)
+++ osprey/be/opt/opt_htable.cxx (working copy)
@@ -2544,13 +2544,18 @@
CODEREP *retv;
OPERATOR oper = OPCODE_operator(opc);
- // make sure the dtyp for constant base is Pointer_type
+#if defined(TARG_X8664)
+ // make sure the dtyp for constant base is Pointer_type if the address
+ // is negative because movl on x86_64 does zero-ext.
if (lbase != NULL && lbase->Kind() == CK_CONST
+ && lbase->Const_val() + (INT64)ofst < 0
&& lbase->Dtyp() != Pointer_type)
lbase->Set_dtyp_strictly(Pointer_type);
if (sbase != NULL && sbase->Kind() == CK_CONST
+ && sbase->Const_val() + (INT64)ofst < 0
&& sbase->Dtyp() != Pointer_type)
sbase->Set_dtyp_strictly(Pointer_type);
+#endif
cr->Init_ivar(opc, dtyp, occ, dsctyp, lodty, lbase, sbase,
ofst, size, field_id);
Since the difference between movl and movq only appears on x86, this
change is made to be x86-specific. In this patch, only negative offset
is handled because If the constant is greater than 2^31, I8/U8 will be
used when CODEREP is created.
--
Regards,
Lai Jian-Xin
830.new.patch
Description: Binary data
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