diff options
Diffstat (limited to 'src/compiler/nir/nir_from_ssa.c')
| -rw-r--r-- | src/compiler/nir/nir_from_ssa.c | 20 |
1 files changed, 15 insertions, 5 deletions
diff --git a/src/compiler/nir/nir_from_ssa.c b/src/compiler/nir/nir_from_ssa.c index 2ac67b2b997..b5d79b37459 100644 --- a/src/compiler/nir/nir_from_ssa.c +++ b/src/compiler/nir/nir_from_ssa.c @@ -827,7 +827,7 @@ nir_convert_from_ssa(nir_shader *shader, bool phi_webs_only) static void place_phi_read(nir_shader *shader, nir_register *reg, - nir_ssa_def *def, nir_block *block) + nir_ssa_def *def, nir_block *block, unsigned depth) { if (block != def->parent_instr->block) { /* Try to go up the single-successor tree */ @@ -840,14 +840,24 @@ place_phi_read(nir_shader *shader, nir_register *reg, } } - if (all_single_successors) { + if (all_single_successors && depth < 32) { /* All predecessors of this block have exactly one successor and it * is this block so they must eventually lead here without * intersecting each other. Place the reads in the predecessors * instead of this block. + * + * We only let this function recurse 32 times because it can recurse + * indefinitely in the presence of infinite loops. Because we're + * crawling a single-successor chain, it doesn't matter where we + * place it so it's ok to stop at an arbitrary distance. + * + * TODO: One day, we could detect back edges and avoid the recursion + * that way. */ - set_foreach(block->predecessors, entry) - place_phi_read(shader, reg, def, (nir_block *)entry->key); + set_foreach(block->predecessors, entry) { + place_phi_read(shader, reg, def, (nir_block *)entry->key, + depth + 1); + } return; } } @@ -902,7 +912,7 @@ nir_lower_phis_to_regs_block(nir_block *block) nir_foreach_phi_src(src, phi) { assert(src->src.is_ssa); - place_phi_read(shader, reg, src->src.ssa, src->pred); + place_phi_read(shader, reg, src->src.ssa, src->pred, 0); } nir_instr_remove(&phi->instr); |