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Take into account ENTRY nodes, but prefer paths from START

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This commit is contained in:
Dmitry Stogov 2022-09-14 23:59:54 +03:00
parent a80fac2cab
commit 96234f5257
1 changed files with 31 additions and 6 deletions
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37
ir_cfg.c
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@ -292,13 +292,23 @@ static void compute_postnum(const ir_ctx *ctx, uint32_t *cur, uint32_t b)
* Cooper, Harvey and Kennedy. */
int ir_build_dominators_tree(ir_ctx *ctx)
{
uint32_t blocks_count, b;
uint32_t blocks_count, b, postnum;
ir_block *blocks, *bb;
uint32_t *edges;
bool changed;
b = 1;
compute_postnum(ctx, &b, 1);
postnum = 1;
compute_postnum(ctx, &postnum, 1);
if (ctx->ir_base[1].op2) {
for (b = 2, bb = &ctx->cfg_blocks[2]; b <= ctx->cfg_blocks_count; b++, bb++) {
if (bb->flags & IR_BB_ENTRY) {
compute_postnum(ctx, &postnum, b);
bb->idom = 1;
}
}
ctx->cfg_blocks[1].postnum = postnum;
}
/* Find immediate dominators */
blocks = ctx->cfg_blocks;
@ -312,7 +322,19 @@ int ir_build_dominators_tree(ir_ctx *ctx)
if (bb->flags & IR_BB_UNREACHABLE) {
continue;
}
if (bb->predecessors_count) {
if (bb->predecessors_count == 1) {
int idom = 0;
uint32_t pred_b = edges[bb->predecessors];
ir_block *pred_bb = &blocks[pred_b];
if (pred_bb->idom > 0) {
idom = pred_b;
}
if (idom > 0 && bb->idom != idom) {
bb->idom = idom;
changed = 1;
}
} else if (bb->predecessors_count) {
int idom = 0;
uint32_t k = bb->predecessors_count;
uint32_t *p = edges + bb->predecessors;
@ -320,7 +342,7 @@ int ir_build_dominators_tree(ir_ctx *ctx)
uint32_t pred_b = *p;
ir_block *pred_bb = &blocks[pred_b];
if (pred_bb->idom > 0) {
if (pred_bb->idom > 0 && !(pred_bb->flags & IR_BB_ENTRY)) {
if (idom == 0) {
idom = pred_b;
} else if (idom != pred_b) {
@ -356,7 +378,10 @@ int ir_build_dominators_tree(ir_ctx *ctx)
if (bb->flags & IR_BB_UNREACHABLE) {
continue;
}
if (bb->idom > 0) {
if (bb->flags & IR_BB_ENTRY) {
bb->idom = 0;
bb->dom_depth = 0;
} else if (bb->idom > 0) {
ir_block *idom_bb = &blocks[bb->idom];
bb->dom_depth = idom_bb->dom_depth + 1;