Mesa (master): spirv: Relax the validation conditions of OpSelect

[Jason Ekstrand]

Module: Mesa
Branch: master
Commit: 3be382cd7cb637f463a4618dc19d87d66a644b0e
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=3be382cd7cb637f463a4618dc19d87d66a644b0e

Author: Jason Ekstrand <jason.ekstrand at intel.com>
Date:   Thu Dec 14 19:53:05 2017 -0800

spirv: Relax the validation conditions of OpSelect

The Talos Principle contains shaders with an OpSelect between two
vectors where the condition is a scalar boolean.  This is technically
against the spec bout nir_builder gracefully handles it by splatting
out the condition to all the channels.  So long as the condition is a
boolean, just emit a warning instead of failing.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104246

---

 src/compiler/spirv/spirv_to_nir.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/src/compiler/spirv/spirv_to_nir.c b/src/compiler/spirv/spirv_to_nir.c
index 0493dd3a8b..39c0b5f5db 100644
--- a/src/compiler/spirv/spirv_to_nir.c
+++ b/src/compiler/spirv/spirv_to_nir.c
@@ -3511,10 +3511,27 @@ vtn_handle_body_instruction(struct vtn_builder *b, SpvOp opcode,
          vtn_fail("Result type of OpSelect must be a scalar, vector, or pointer");
       }
 
-      vtn_fail_if(sel_val->type->type != sel_type,
-                  "Condition type of OpSelect must be a scalar or vector of "
-                  "Boolean type. It must have the same number of components "
-                  "as Result Type");
+      if (unlikely(sel_val->type->type != sel_type)) {
+         if (sel_val->type->type == glsl_bool_type()) {
+            /* This case is illegal but some older versions of GLSLang produce
+             * it.  The GLSLang issue was fixed on March 30, 2017:
+             *
+             * https://github.com/KhronosGroup/glslang/issues/809
+             *
+             * Unfortunately, there are applications in the wild which are
+             * shipping with this bug so it isn't nice to fail on them so we
+             * throw a warning instead.  It's not actually a problem for us as
+             * nir_builder will just splat the condition out which is most
+             * likely what the client wanted anyway.
+             */
+            vtn_warn("Condition type of OpSelect must have the same number "
+                     "of components as Result Type");
+         } else {
+            vtn_fail("Condition type of OpSelect must be a scalar or vector "
+                     "of Boolean type. It must have the same number of "
+                     "components as Result Type");
+         }
+      }
 
       vtn_fail_if(obj1_val->type != res_val->type ||
                   obj2_val->type != res_val->type,