From ed5af9437344f932f8cbebfa776f873d16a8aae1 Mon Sep 17 00:00:00 2001 From: Matt Turner Date: Thu, 26 Apr 2018 21:25:42 -0700 Subject: [PATCH] nir: Transform discard_if(true) into discard Noticed while reviewing Tim Arceri's NIR inlining series. Without his series: instructions in affected programs: 16 -> 14 (-12.50%) helped: 2 With his series: instructions in affected programs: 196 -> 174 (-11.22%) helped: 22 Reviewed-by: Jason Ekstrand --- src/compiler/nir/nir_opt_constant_folding.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/src/compiler/nir/nir_opt_constant_folding.c b/src/compiler/nir/nir_opt_constant_folding.c index a848b145874..fe34f4ade8b 100644 --- a/src/compiler/nir/nir_opt_constant_folding.c +++ b/src/compiler/nir/nir_opt_constant_folding.c @@ -167,7 +167,22 @@ constant_fold_intrinsic_instr(nir_intrinsic_instr *instr) if (instr->intrinsic == nir_intrinsic_discard_if) { nir_const_value *src_val = nir_src_as_const_value(instr->src[0]); - if (src_val && src_val->u32[0] == 0) { + if (src_val && src_val->u32[0] == NIR_FALSE) { + nir_instr_remove(&instr->instr); + progress = true; + } else if (src_val && src_val->u32[0] == NIR_TRUE) { + /* This method of getting a nir_shader * from a nir_instr is + * admittedly gross, but given the rarity of hitting this case I think + * it's preferable to plumbing an otherwise unused nir_shader * + * parameter through four functions to get here. + */ + nir_cf_node *cf_node = &instr->instr.block->cf_node; + nir_function_impl *impl = nir_cf_node_get_function(cf_node); + nir_shader *shader = impl->function->shader; + + nir_intrinsic_instr *discard = + nir_intrinsic_instr_create(shader, nir_intrinsic_discard); + nir_instr_insert_before(&instr->instr, &discard->instr); nir_instr_remove(&instr->instr); progress = true; } -- 2.30.2