From 125574d1effcb3e3eda93f2b2975bc6cc606df3e Mon Sep 17 00:00:00 2001 From: Jason Ekstrand Date: Mon, 13 Apr 2015 14:13:16 -0700 Subject: [PATCH] nir/lower_source_mods: Don't propagate register sources The nir_lower_source_mods pass does a weak form of copy propagation to clean up all of the mov-with-negate's that get generated. However, we weren't properly checking that the sources were SSA and so we could end up moving a register read which is not, in general, valid. Reviewed-by: Connor Abbott --- src/glsl/nir/nir_lower_to_source_mods.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/glsl/nir/nir_lower_to_source_mods.c b/src/glsl/nir/nir_lower_to_source_mods.c index d6bf77f..7b4a0f6 100644 --- a/src/glsl/nir/nir_lower_to_source_mods.c +++ b/src/glsl/nir/nir_lower_to_source_mods.c @@ -67,6 +67,13 @@ nir_lower_to_source_mods_block(nir_block *block, void *state) continue; } + /* We can only do a rewrite if the source we are copying is SSA. + * Otherwise, moving the read might invalidly reorder reads/writes + * on a register. + */ + if (!parent->src[0].src.is_ssa) + continue; + nir_instr_rewrite_src(instr, &alu->src[i].src, parent->src[0].src); if (alu->src[i].abs) { /* abs trumps both neg and abs, do nothing */ -- 2.7.4