From 902b0ccc9a5266955d104dc7652ac00e66081f95 Mon Sep 17 00:00:00 2001 From: Jason Ekstrand Date: Wed, 4 Feb 2015 21:38:28 -0800 Subject: [PATCH] nir/from_ssa: Don't try to read an invalid instruction Right now, the nir_instr_prev function function blindly looks up the previous element in the exec list and casts it to an instruction even if it's the tail sentinel. The next commit will change this to return null if it's the first instruction. Making this change first avoids getting a segfault between commits. The only reason we never noticed is that, thanks to the way things are laid out in nir_block, the casted instruction's type was never parallal_copy. Reviewed-by: Connor Abbott --- src/glsl/nir/nir_from_ssa.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/glsl/nir/nir_from_ssa.c b/src/glsl/nir/nir_from_ssa.c index 3625237dd3d..7c500957767 100644 --- a/src/glsl/nir/nir_from_ssa.c +++ b/src/glsl/nir/nir_from_ssa.c @@ -272,7 +272,7 @@ get_parallel_copy_at_end_of_block(nir_block *block) if (last_instr->type == nir_instr_type_jump) last_instr = nir_instr_prev(last_instr); - if (last_instr->type == nir_instr_type_parallel_copy) + if (last_instr && last_instr->type == nir_instr_type_parallel_copy) return nir_instr_as_parallel_copy(last_instr); else return NULL; -- 2.30.2