tgsi/gs: bound max output vertices in shader

This limits the number of emitted vertices to the shaders max output
vertices, and avoids us writing things into memory that isn't big
enough for it.

Reviewed-by: Zack Rusin <zackr@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/gallium/auxiliary/tgsi/tgsi_exec.c

@@ -789,6 +789,11 @@ tgsi_exec_machine_bind_shader(
          break;
 
       case TGSI_TOKEN_TYPE_PROPERTY:
+         if (mach->Processor == TGSI_PROCESSOR_GEOMETRY) {
+            if (parse.FullToken.FullProperty.Property.PropertyName == TGSI_PROPERTY_GS_MAX_OUTPUT_VERTICES) {
+               mach->MaxOutputVertices = parse.FullToken.FullProperty.u[0].Data;
+            }
+         }
          break;
 
       default:
@@ -1621,6 +1626,9 @@ emit_vertex(struct tgsi_exec_machine *mach)
          if ((mach->ExecMask & (1 << i)))
    */
    if (mach->ExecMask) {
+      if (mach->Primitives[mach->Temps[TEMP_PRIMITIVE_I].xyzw[TEMP_PRIMITIVE_C].u[0]] >= mach->MaxOutputVertices)
+         return;
+
       mach->Temps[TEMP_OUTPUT_I].xyzw[TEMP_OUTPUT_C].u[0] += mach->NumOutputs;
       mach->Primitives[mach->Temps[TEMP_PRIMITIVE_I].xyzw[TEMP_PRIMITIVE_C].u[0]]++;
    }

src/gallium/auxiliary/tgsi/tgsi_exec.h

@@ -297,6 +297,7 @@ struct tgsi_exec_machine
    unsigned                      *Primitives;
    unsigned                       NumOutputs;
    unsigned                       MaxGeometryShaderOutputs;
+   unsigned                       MaxOutputVertices;
 
    /* FRAGMENT processor only. */
    const struct tgsi_interp_coef *InterpCoefs;