interpreters/git/peephole.c

   1 // $Id: peephole.c,v 1.6 2003/10/13 22:53:04 iain Exp $
   2 // Peephole optimiser for git
   3
   4 #include "git.h"
   5
   6 static Label sLastOp;
   7
   8 extern void resetPeepholeOptimiser ()
   9 {
  10     sLastOp = label_nop;
  11 }
  12
  13 #define REPLACE_SINGLE(lastOp,thisOp,newOp) \
  14     case label_ ## thisOp:                  \
  15         if (sLastOp == label_ ## lastOp)    \
  16         {                                   \
  17             op = label_ ## newOp;           \
  18             goto replaceNoOperands;         \
  19         }                                   \
  20         break
  21
  22 #define CASE_NO_OPERANDS(lastOp,newOp) \
  23     case label_ ## lastOp: op = label_ ## newOp; goto replaceNoOperands
  24
  25 #define CASE_ONE_OPERAND(lastOp,newOp) \
  26     case label_ ## lastOp: op = label_ ## newOp; goto replaceOneOperand
  27
  28 #define REPLACE_STORE(storeOp) \
  29     case label_ ## storeOp:                                             \
  30         switch(sLastOp)                                                 \
  31         {                                                               \
  32             CASE_NO_OPERANDS (add_discard,      add_ ## storeOp);       \
  33             CASE_NO_OPERANDS (sub_discard,      sub_ ## storeOp);       \
  34             CASE_NO_OPERANDS (mul_discard,      mul_ ## storeOp);       \
  35             CASE_NO_OPERANDS (div_discard,      div_ ## storeOp);       \
  36             CASE_NO_OPERANDS (mod_discard,      mod_ ## storeOp);       \
  37             CASE_NO_OPERANDS (neg_discard,      neg_ ## storeOp);       \
  38             CASE_NO_OPERANDS (bitand_discard,   bitand_ ## storeOp);    \
  39             CASE_NO_OPERANDS (bitor_discard,    bitor_ ## storeOp);     \
  40             CASE_NO_OPERANDS (bitxor_discard,   bitxor_ ## storeOp);    \
  41             CASE_NO_OPERANDS (bitnot_discard,   bitnot_ ## storeOp);    \
  42             CASE_NO_OPERANDS (shiftl_discard,   shiftl_ ## storeOp);    \
  43             CASE_NO_OPERANDS (sshiftr_discard,  sshiftr_ ## storeOp);   \
  44             CASE_NO_OPERANDS (ushiftr_discard,  ushiftr_ ## storeOp);   \
  45             CASE_NO_OPERANDS (copys_discard,    copys_ ## storeOp);     \
  46             CASE_NO_OPERANDS (copyb_discard,    copyb_ ## storeOp);     \
  47             CASE_NO_OPERANDS (sexs_discard,     sexs_ ## storeOp);      \
  48             CASE_NO_OPERANDS (sexb_discard,     sexb_ ## storeOp);      \
  49             CASE_NO_OPERANDS (aload_discard,    aload_ ## storeOp);     \
  50             CASE_NO_OPERANDS (aloads_discard,   aloads_ ## storeOp);    \
  51             CASE_NO_OPERANDS (aloadb_discard,   aloadb_ ## storeOp);    \
  52             CASE_NO_OPERANDS (aloadbit_discard, aloadbit_ ## storeOp);  \
  53             default: break;                                             \
  54         }                                                               \
  55         break
  56
  57 #define REPLACE_L1_L2(mode2)                                    \
  58     case label_L2_ ## mode2:                                    \
  59         switch(sLastOp)                                         \
  60         {                                                       \
  61             CASE_ONE_OPERAND (L1_const, L1_const_L2_ ## mode2); \
  62             CASE_NO_OPERANDS (L1_stack, L1_stack_L2_ ## mode2); \
  63             CASE_ONE_OPERAND (L1_local, L1_local_L2_ ## mode2); \
  64             CASE_ONE_OPERAND (L1_addr,  L1_addr_L2_ ## mode2);  \
  65             default: break;                                     \
  66         }                                                       \
  67         break
  68
  69 #define REPLACE_LOAD_OP(loadOp,reg)                                         \
  70     case label_ ## loadOp:                                                  \
  71         switch(sLastOp)                                                     \
  72         {                                                                   \
  73             CASE_ONE_OPERAND (reg ## _const, loadOp ## _ ## reg ## _const); \
  74             CASE_NO_OPERANDS (reg ## _stack, loadOp ## _ ## reg ## _stack); \
  75             CASE_ONE_OPERAND (reg ## _local, loadOp ## _ ## reg ## _local); \
  76             CASE_ONE_OPERAND (reg ## _addr,  loadOp ## _ ## reg ## _addr);  \
  77             default: break;                                                 \
  78         }                                                                   \
  79         break
  80
  81 extern void emitCode (Label op)
  82 {
  83     git_uint32 temp;
  84
  85     if (gPeephole)
  86     {
  87         switch (op)
  88         {
  89             REPLACE_SINGLE (args_stack, call_stub_discard, args_stack_call_stub_discard);
  90             REPLACE_SINGLE (args_stack, call_stub_addr,    args_stack_call_stub_addr);
  91             REPLACE_SINGLE (args_stack, call_stub_local,   args_stack_call_stub_local);
  92             REPLACE_SINGLE (args_stack, call_stub_stack,   args_stack_call_stub_stack);
  93
  94             REPLACE_STORE (S1_stack);
  95             REPLACE_STORE (S1_local);
  96             REPLACE_STORE (S1_addr);
  97
  98             REPLACE_L1_L2 (const);
  99             REPLACE_L1_L2 (stack);
 100             REPLACE_L1_L2 (local);
 101             REPLACE_L1_L2 (addr);
 102
 103             REPLACE_LOAD_OP (return, L1);
 104             REPLACE_LOAD_OP (astore, L3);
 105             REPLACE_LOAD_OP (astores, L3);
 106             REPLACE_LOAD_OP (astoreb, L3);
 107             REPLACE_LOAD_OP (astorebit, L3);
 108
 109             default: break;
 110         }
 111     }
 112     goto noPeephole;
 113
 114 replaceOneOperand:
 115     // The previous opcode has one operand, so
 116     // we have to go back two steps to update it.
 117     temp = undoEmit();  // Save the operand.
 118     undoEmit();         // Remove the old opcode.
 119     emitFinalCode (op); // Emit the new opcode.
 120     emitData (temp);    // Emit the operand again.
 121     goto done;
 122
 123 replaceNoOperands:
 124     undoEmit();
 125     // ... fall through
 126 noPeephole:
 127     emitFinalCode (op);
 128     // ... fall through
 129 done:
 130     sLastOp = op;
 131 }