[Mono-dev] Global register allocator in JIT

[Sergey Tikhonov]

Zoltan Varga wrote:
>                                 Hi,
>
> To match the example, these should use OP_LADD instead of CEE_ADD. The
> burg phase has an optimization to avoid useless moves when compiling
> trees of the form:
> (stind.i regvar[REG] (TREE))
> It is turned on by defining MONO_ARCH_ENABLE_EMIT_STATE_OPT in the
> mini-<ARCH>.h file. It is defined for alpha, so I don't know why it is
> not working
> there. It does on other architectures.
Thank you. The macro was not defined (it was in file, but was not active 
:) ).
I defined it and it helped. The code looks better now, but there are 
still some issues.
I checked generated code for amd64 - here is something interesting (the 
same method):
LABEL BLOCK 12:
 (stind.i2 (long_add (long_conv_to_i (ldind.i regvar[%r13])) iconst[0]) 
(ldind.i2 (long_add (long_conv_to_i (ldind.i regvar[%r14])) iconst[0])))
 (stind.i regvar[%r13] (long_add (long_conv_to_i (ldind.i regvar[%r13])) 
iconst[2]))
 (stind.i regvar[%r14] (long_add (long_conv_to_i (ldind.i regvar[%r14])) 
iconst[2]))
 (stind.i4 regvar[%r15] (sub (ldind.i4 regvar[%r15]) iconst[2]))

LOCAL REGALLOC: BASIC BLOCK: 12
        1  move R16 <- %r13
        2  move R19 <- %r14
        3  loadi2_membase R18 <- R19
        4  storei2_membase_reg [R16] <- R18
        5  move R21 <- %r13
        6  add_imm %r13 <- R21 clobbers: 1
        7  move %r13 <- %r13
        8  move R23 <- %r14
        9  add_imm %r14 <- R23 clobbers: 1
        10 move %r14 <- %r14
        11 sub_imm %r15 <- %r15 clobbers: 1

<BB>:12
  b0:   49 8b c5                mov    %r13,%rax
  b3:   49 8b ce                mov    %r14,%rcx
  b6:   48 0f bf 09             movswq (%rcx),%rcx
  ba:   66 89 08                mov    %cx,(%rax)
  bd:   49 8b c5                mov    %r13,%rax     <-- ????
  c0:   49 83 c5 02             add    $0x2,%r13
  c4:   49 8b c6                mov    %r14,%rax    <-- ????
  c7:   49 83 c6 02             add    $0x2,%r14
  cb:   49 83 ef 02             sub    $0x2,%r15


Thank you for helping me out (I will have more questions :) )

Regards,
Sergey.