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src/cpu/ppc/vm/templateInterpreterGenerator_ppc.cpp

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rev 12310 : Reserve R30 to a cleared content register on C1 and C2 code

Several times a 0 is loaded to a register as a temporary value. This can be
improved by caching a 0 into a register.

I didn't notice a performance drop since only applying this patch showed no
drop of performance, hence there are more registers available than normally
needed and this caching technique can be applied.

Despite setting R30_zero as a dedicated register and initialized with 0 for the
C1 and C2 code, new rules for storing 0 related to stb,sth,stw,std were added.


1036 
1037   // Cut back area between esp and max_stack.
1038   __ addi(parent_frame_resize, parent_frame_resize, frame::abi_minframe_size - Interpreter::stackElementSize);
1039 
1040   __ round_to(top_frame_size, frame::alignment_in_bytes);
1041   __ round_to(parent_frame_resize, frame::alignment_in_bytes);
1042   // parent_frame_resize = (locals-parameters) - (ESP-SP-ABI48) Rounded to frame alignment size.
1043   // Enlarge by locals-parameters (not in case of native_call), shrink by ESP-SP-ABI48.
1044 
1045   if (!native_call) {
1046     // Stack overflow check.
1047     // Native calls don't need the stack size check since they have no
1048     // expression stack and the arguments are already on the stack and
1049     // we only add a handful of words to the stack.
1050     __ add(R11_scratch1, parent_frame_resize, top_frame_size);
1051     generate_stack_overflow_check(R11_scratch1, R12_scratch2);
1052   }
1053 
1054   // Set up interpreter state registers.
1055 

1056   __ add(R18_locals, R15_esp, Rsize_of_parameters);
1057   __ ld(R27_constPoolCache, in_bytes(ConstMethod::constants_offset()), Rconst_method);
1058   __ ld(R27_constPoolCache, ConstantPool::cache_offset_in_bytes(), R27_constPoolCache);
1059 
1060   // Set method data pointer.
1061   if (ProfileInterpreter) {
1062     Label zero_continue;
1063     __ ld(R28_mdx, method_(method_data));
1064     __ cmpdi(CCR0, R28_mdx, 0);
1065     __ beq(CCR0, zero_continue);
1066     __ addi(R28_mdx, R28_mdx, in_bytes(MethodData::data_offset()));
1067     __ bind(zero_continue);
1068   }
1069 
1070   if (native_call) {
1071     __ li(R14_bcp, 0); // Must initialize.
1072   } else {
1073     __ add(R14_bcp, in_bytes(ConstMethod::codes_offset()), Rconst_method);
1074   }
1075 




1036 
1037   // Cut back area between esp and max_stack.
1038   __ addi(parent_frame_resize, parent_frame_resize, frame::abi_minframe_size - Interpreter::stackElementSize);
1039 
1040   __ round_to(top_frame_size, frame::alignment_in_bytes);
1041   __ round_to(parent_frame_resize, frame::alignment_in_bytes);
1042   // parent_frame_resize = (locals-parameters) - (ESP-SP-ABI48) Rounded to frame alignment size.
1043   // Enlarge by locals-parameters (not in case of native_call), shrink by ESP-SP-ABI48.
1044 
1045   if (!native_call) {
1046     // Stack overflow check.
1047     // Native calls don't need the stack size check since they have no
1048     // expression stack and the arguments are already on the stack and
1049     // we only add a handful of words to the stack.
1050     __ add(R11_scratch1, parent_frame_resize, top_frame_size);
1051     generate_stack_overflow_check(R11_scratch1, R12_scratch2);
1052   }
1053 
1054   // Set up interpreter state registers.
1055 
1056   __ li(R30_zero, 0);
1057   __ add(R18_locals, R15_esp, Rsize_of_parameters);
1058   __ ld(R27_constPoolCache, in_bytes(ConstMethod::constants_offset()), Rconst_method);
1059   __ ld(R27_constPoolCache, ConstantPool::cache_offset_in_bytes(), R27_constPoolCache);
1060 
1061   // Set method data pointer.
1062   if (ProfileInterpreter) {
1063     Label zero_continue;
1064     __ ld(R28_mdx, method_(method_data));
1065     __ cmpdi(CCR0, R28_mdx, 0);
1066     __ beq(CCR0, zero_continue);
1067     __ addi(R28_mdx, R28_mdx, in_bytes(MethodData::data_offset()));
1068     __ bind(zero_continue);
1069   }
1070 
1071   if (native_call) {
1072     __ li(R14_bcp, 0); // Must initialize.
1073   } else {
1074     __ add(R14_bcp, in_bytes(ConstMethod::codes_offset()), Rconst_method);
1075   }
1076
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