From 57fba85da408dd4ec98508b5106c156d616b5602 Mon Sep 17 00:00:00 2001 From: Samuel Pitoiset Date: Thu, 3 Sep 2020 22:02:01 +0200 Subject: [PATCH] spirv: fix emitting switch cases that directly jump to the merge block MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit As shown in the valid SPIR-V below, if one switch case statement directly jumps to the merge block, it has no branches at all and we have to reset the fall variable. Otherwise, it creates an unintentional fallthrough. OpSelectionMerge %97 None OpSwitch %96 %97 1 %99 2 %100 %100 = OpLabel %102 = OpAccessChain %_ptr_StorageBuffer_v4float %86 %uint_0 %uint_37 %103 = OpLoad %v4float %102 %104 = OpBitcast %v4uint %103 %105 = OpCompositeExtract %uint %104 0 %106 = OpShiftLeftLogical %uint %105 %uint_1 OpBranch %97 %99 = OpLabel OpBranch %97 %97 = OpLabel %107 = OpPhi %uint %uint_4 %75 %uint_5 %99 %106 %100 This fixes serious corruption in Horizon Zero Dawn. v2: Changed the code to skip the entire if-block instead of resetting the fallthrough variable. Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/3460 Cc: mesa-stable Signed-off-by: Samuel Pitoiset Signed-off-by: Bas Nieuwenhuizen Reviewed-by: Daniel Schürmann Part-of: --- src/compiler/spirv/vtn_cfg.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/compiler/spirv/vtn_cfg.c b/src/compiler/spirv/vtn_cfg.c index 83ca13b734c..a1573565b81 100644 --- a/src/compiler/spirv/vtn_cfg.c +++ b/src/compiler/spirv/vtn_cfg.c @@ -1165,6 +1165,13 @@ vtn_emit_cf_list_structured(struct vtn_builder *b, struct list_head *cf_list, vtn_foreach_cf_node(case_node, &vtn_switch->cases) { struct vtn_case *cse = vtn_cf_node_as_case(case_node); + /* If this case jumps directly to the break block, we don't have + * to handle the case as the body is empty and doesn't fall + * through. + */ + if (cse->block == vtn_switch->break_block) + continue; + /* Figure out the condition */ nir_ssa_def *cond = vtn_switch_case_condition(b, vtn_switch, sel, cse); -- 2.30.2