[Pnet-developers] mk_local_n

[Miroslaw Dobrzanski-Neumann]

Hi,

in the unroller there is not code code for COP_MK_LOCAL_N.
I have provided the following piece of code in unroll_var.c
and got about 9% better score in pnetmark.Logic on my P4

The Run() method has more than 3 local words

391 #ifdef CVM_X86
392 case COP_MK_LOCAL_N:
393 {
394     unsigned temp = CVM_ARG_WIDE_SMALL;
395     UNROLL_START();
396     FlushRegisterStack(&unroll);
397     if (X86_EDI == MD_REG_STACK && 0 == unroll.stackHeight) {
398             x86_clear_reg (unroll.out, X86_EAX);
399             x86_mov_reg_imm (unroll.out, X86_ECX, temp);
400             x86_prefix (unroll.out, X86_REPZ_PREFIX);
401             x86_stosl (unroll.out);
402     }
403     else {
404             unsigned idx;
405             md_clear_membase_start(unroll.out);
406             for (idx = 0; idx < temp; idx++) {
407                     md_clear_membase(unroll.out, MD_REG_STACK, (idx * 
sizeof(CVMWord)) + unroll.stackHeight);
408             }
409     }
410     unroll.stackHeight += temp * sizeof(CVMWord);
411     MODIFY_UNROLL_PC(CVM_LEN_WIDE_SMALL);
412 }
413 break;
414 #endif

Generally every method with more than 3 local words will benefit from this
piece of code such as:
System.Array::Copy ()
System.Text.StringBuilder::AppendSpace ()


This code bases on the documented assumption

mk_local_n:
...
Notes:
This instruction is used to allocate local variable space at the start of a 
method.

So the scratch registers X86_EAX, X86_ECX have not been used before and it
is safe to use them directly



To get rid of the platform specific code (here x86) a new md_* macro is needed

md_clear_membase_len(inst,reg,pos,bytelen)



Could you verify and merge into cvs

Regards,
-- 
Mirosław Dobrzański-Neumann
E-mail: address@hidden

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