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Remove useless IR when fusing instructions #234

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merged 1 commit into from
Oct 3, 2023
Merged

Remove useless IR when fusing instructions #234

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74 changes: 44 additions & 30 deletions src/emulate.c
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Original file line number Diff line number Diff line change
Expand Up @@ -398,29 +398,18 @@ enum {
#undef _
};

/* FIXME: This will simply find the n-th instruction by iterating
* the linked list linearly, we may want to find better approach. */
FORCE_INLINE rv_insn_t *next_nth_insn(rv_insn_t *ir, int32_t n)
{
rv_insn_t *tmp = ir;
for (int32_t iter = 0; iter < n; iter++)
tmp = tmp->next;
return tmp;
}

/* multiple lui */
static bool do_fuse1(riscv_t *rv, rv_insn_t *ir)
{
rv->csr_cycle += ir->imm2;
int i;
rv_insn_t *cur_ir;
for (i = 0, cur_ir = ir; i < ir->imm2; i++, cur_ir = cur_ir->next) {
rv->X[cur_ir->rd] = cur_ir->imm;
opcode_fuse_t *fuse = ir->fuse;
for (int i = 0; i < ir->imm2; i++) {
rv->X[fuse[i].rd] = fuse[i].imm;
}
rv->PC += ir->imm2 * ir->insn_len;
if (unlikely(RVOP_NO_NEXT(ir)))
return true;
const rv_insn_t *next = next_nth_insn(ir, ir->imm2);
const rv_insn_t *next = ir->next;
MUST_TAIL return next->impl(rv, next);
}

Expand All @@ -433,7 +422,7 @@ static bool do_fuse2(riscv_t *rv, rv_insn_t *ir)
rv->PC += 2 * ir->insn_len;
if (unlikely(RVOP_NO_NEXT(ir)))
return true;
const rv_insn_t *next = next_nth_insn(ir, 2);
const rv_insn_t *next = ir->next;
MUST_TAIL return next->impl(rv, next);
}

Expand All @@ -456,7 +445,7 @@ static bool do_fuse3(riscv_t *rv, rv_insn_t *ir)
rv->PC += ir->imm2 * ir->insn_len;
if (unlikely(RVOP_NO_NEXT(ir)))
return true;
const rv_insn_t *next = next_nth_insn(ir, ir->imm2);
const rv_insn_t *next = ir->next;
MUST_TAIL return next->impl(rv, next);
}

Expand All @@ -479,7 +468,7 @@ static bool do_fuse4(riscv_t *rv, rv_insn_t *ir)
rv->PC += ir->imm2 * ir->insn_len;
if (unlikely(RVOP_NO_NEXT(ir)))
return true;
const rv_insn_t *next = next_nth_insn(ir, ir->imm2);
const rv_insn_t *next = ir->next;
MUST_TAIL return next->impl(rv, next);
}

Expand Down Expand Up @@ -622,7 +611,7 @@ static void block_translate(riscv_t *rv, block_map_t *map, block_t *block)
for (int j = 1; j < count; j++, next_ir = next_ir->next) { \
memcpy(ir->fuse + j, next_ir, sizeof(opcode_fuse_t)); \
} \
ir->tailcall = next_ir->tailcall; \
remove_next_nth_ir(rv, ir, block, count - 1); \
}

static bool detect_memset(riscv_t *rv, int lib)
Expand Down Expand Up @@ -851,6 +840,23 @@ static bool detect_memcpy(riscv_t *rv, int lib)
return true;
}

FORCE_INLINE void remove_next_nth_ir(riscv_t *rv,
rv_insn_t *ir,
block_t *block,
uint8_t n)
{
for (uint8_t i = 0; i < n; i++) {
rv_insn_t *next = ir->next;
ir->next = ir->next->next;
mpool_free(rv->block_map.block_ir_mp, next);
}
if (!ir->next) {
block->ir_tail = ir;
ir->tailcall = true;
}
block->n_insn -= n;
}

static bool libc_substitute(riscv_t *rv, block_t *block)
{
rv_insn_t *ir = block->ir_head, *next_ir = NULL;
Expand All @@ -872,7 +878,7 @@ static bool libc_substitute(riscv_t *rv, block_t *block)
if (detect_memset(rv, 1)) {
ir->opcode = rv_insn_fuse5;
ir->impl = dispatch_table[ir->opcode];
ir->tailcall = true;
remove_next_nth_ir(rv, ir, block, 2);
return true;
};
}
Expand All @@ -885,12 +891,12 @@ static bool libc_substitute(riscv_t *rv, block_t *block)
if (next_ir->imm == 20 && detect_memset(rv, 2)) {
ir->opcode = rv_insn_fuse5;
ir->impl = dispatch_table[ir->opcode];
ir->tailcall = true;
remove_next_nth_ir(rv, ir, block, 2);
return true;
} else if (next_ir->imm == 28 && detect_memcpy(rv, 2)) {
ir->opcode = rv_insn_fuse6;
ir->impl = dispatch_table[ir->opcode];
ir->tailcall = true;
remove_next_nth_ir(rv, ir, block, 2);
return true;
};
}
Expand Down Expand Up @@ -918,7 +924,7 @@ static bool libc_substitute(riscv_t *rv, block_t *block)
if (detect_memcpy(rv, 1)) {
ir->opcode = rv_insn_fuse6;
ir->impl = dispatch_table[ir->opcode];
ir->tailcall = true;
remove_next_nth_ir(rv, ir, block, 3);
return true;
};
}
Expand All @@ -938,7 +944,7 @@ static bool libc_substitute(riscv_t *rv, block_t *block)
* Strategies are being devised to increase the number of instructions that
* match the pattern, including possible instruction reordering.
*/
static void match_pattern(block_t *block)
static void match_pattern(riscv_t *rv, block_t *block)
{
uint32_t i;
rv_insn_t *ir;
Expand All @@ -960,23 +966,31 @@ static void match_pattern(block_t *block)
ir->rs1 = next_ir->rs2;
ir->impl = dispatch_table[ir->opcode];
ir->tailcall = next_ir->tailcall;
remove_next_nth_ir(rv, ir, block, 1);
}
break;
case rv_insn_lui:
count = 1;
while (1) {
if (next_ir->opcode != rv_insn_lui)
break;
next_ir->opcode = rv_insn_nop;
count++;
if (next_ir->tailcall)
break;
next_ir = next_ir->next;
}
ir->imm2 = count;
ir->opcode = rv_insn_fuse1;
ir->impl = dispatch_table[ir->opcode];
ir->tailcall = next_ir->tailcall;
if (count > 1) {
ir->opcode = rv_insn_fuse1;
ir->fuse = malloc(count * sizeof(opcode_fuse_t));
ir->imm2 = count;
memcpy(ir->fuse, ir, sizeof(opcode_fuse_t));
ir->impl = dispatch_table[ir->opcode];
next_ir = ir->next;
for (int j = 1; j < count; j++, next_ir = next_ir->next) {
memcpy(ir->fuse + j, next_ir, sizeof(opcode_fuse_t));
}
remove_next_nth_ir(rv, ir, block, count - 1);
}
break;
}
break;
Expand Down Expand Up @@ -1055,7 +1069,7 @@ static block_t *block_find_or_translate(riscv_t *rv)
if (likely(!rv->debug_mode))
#endif
/* macro operation fusion */
match_pattern(next);
match_pattern(rv, next);
}
/* insert the block into block map */
block_insert(&rv->block_map, next);
Expand Down