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Better iterative DCE after SCCP

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This commit is contained in:
Dmitry Stogov 2023-04-13 10:39:00 +03:00
parent 7d395532d9
commit 1f447a538b
1 changed files with 37 additions and 4 deletions
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41
ir_sccp.c
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@ -216,6 +216,33 @@ static void ir_sccp_make_nop(ir_ctx *ctx, ir_ref ref)
}
}
static void ir_sccp_remove_insn(ir_ctx *ctx, ir_insn *_values, ir_ref ref, ir_bitqueue *worklist)
{
ir_ref j, n, *p;
ir_use_list *use_list = &ctx->use_lists[ref];
ir_insn *insn;
use_list->refs = 0;
use_list->count = 0;
insn = &ctx->ir_base[ref];
n = ir_input_edges_count(ctx, insn);
insn->opt = IR_NOP; /* keep "inputs_count" */
for (j = 1, p = insn->ops + j; j <= n; j++, p++) {
ir_ref input = *p;
*p = IR_UNUSED;
if (input > 0 && _values[input].op == IR_BOTTOM) {
ir_sccp_remove_from_use_list(ctx, input, ref);
/* schedule DCE */
if ((IR_IS_FOLDABLE_OP(ctx->ir_base[input].op) && ctx->use_lists[input].count == 0)
|| ((ir_op_flags[ctx->ir_base[input].op] & (IR_OP_FLAG_MEM|IR_OP_FLAG_MEM_MASK)) == (IR_OP_FLAG_MEM|IR_OP_FLAG_MEM_LOAD)
&& ctx->use_lists[input].count == 1)) {
ir_bitqueue_add(worklist, input);
}
}
}
}
static void ir_sccp_replace_insn(ir_ctx *ctx, ir_insn *_values, ir_ref ref, ir_ref new_ref, ir_bitqueue *worklist)
{
ir_ref j, n, *p, use, k, l;
@ -226,8 +253,10 @@ static void ir_sccp_replace_insn(ir_ctx *ctx, ir_insn *_values, ir_ref ref, ir_r
insn = &ctx->ir_base[ref];
n = ir_input_edges_count(ctx, insn);
insn->opt = IR_NOP; /* keep "inputs_count" */
for (j = 1, p = insn->ops + 1; j <= n; j++, p++) {
ir_ref input = *p;
*p = IR_UNUSED;
if (input > 0) {
ir_sccp_remove_from_use_list(ctx, input, ref);
/* schedule DCE */
@ -269,7 +298,8 @@ static void ir_sccp_replace_insn(ir_ctx *ctx, ir_insn *_values, ir_ref ref, ir_r
}
}
ir_sccp_make_nop(ctx, ref);
use_list->refs = 0;
use_list->count = 0;
}
static void ir_sccp_fold2(ir_ctx *ctx, ir_insn *_values, ir_ref ref, ir_bitqueue *worklist)
@ -560,6 +590,9 @@ int ir_sccp(ir_ctx *ctx)
if (!changed) {
continue;
}
} else if (ctx->use_lists[i].count == 0) {
/* dead code */
continue;
} else if (EXPECTED(IR_IS_FOLDABLE_OP(insn->op))) {
bool may_benefit = 0;
bool has_top = 0;
@ -786,7 +819,7 @@ int ir_sccp(ir_ctx *ctx)
insn = &ctx->ir_base[i];
if (ir_op_flags[insn->op] & (IR_OP_FLAG_DATA|IR_OP_FLAG_MEM)) {
if (insn->op != IR_PARAM && insn->op != IR_VAR) {
ir_sccp_make_nop(ctx, i);
ir_sccp_remove_insn(ctx, _values, i, &worklist);
}
} else {
if (ir_op_flags[insn->op] & IR_OP_FLAG_TERMINATOR) {
@ -825,7 +858,7 @@ int ir_sccp(ir_ctx *ctx)
insn = &ctx->ir_base[i];
if (IR_IS_FOLDABLE_OP(insn->op)) {
if (ctx->use_lists[i].count == 0) {
ir_sccp_replace_insn(ctx, _values, i, IR_UNUSED, &worklist);
ir_sccp_remove_insn(ctx, _values, i, &worklist);
} else {
ir_sccp_fold2(ctx, _values, i, &worklist);
}
@ -838,7 +871,7 @@ int ir_sccp(ir_ctx *ctx)
ctx->ir_base[next].op1 = insn->op1;
ir_sccp_replace_use(ctx, insn->op1, i, next);
insn->op1 = IR_UNUSED;
ir_sccp_replace_insn(ctx, _values, i, IR_UNUSED, &worklist);
ir_sccp_remove_insn(ctx, _values, i, &worklist);
}
}
}