nir/gather_info: Look for uses of helper invocations

The one obvious omission here is gl_HelperInvocation itself.  However,
the spec doesn't require that we generate then when gl_HelperInvocation
is used, it merely mandates that we report them if they are there.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/compiler/nir/nir_gather_info.c

@@ -264,6 +264,14 @@ gather_intrinsic_info(nir_intrinsic_instr *instr, nir_shader *shader,
          (1ull << nir_system_value_from_intrinsic(instr->intrinsic));
       break;
 
+   case nir_intrinsic_quad_broadcast:
+   case nir_intrinsic_quad_swap_horizontal:
+   case nir_intrinsic_quad_swap_vertical:
+   case nir_intrinsic_quad_swap_diagonal:
+      if (shader->info.stage == MESA_SHADER_FRAGMENT)
+         shader->info.fs.needs_helper_invocations = true;
+      break;
+
    case nir_intrinsic_end_primitive:
    case nir_intrinsic_end_primitive_with_counter:
       assert(shader->info.stage == MESA_SHADER_GEOMETRY);
@@ -284,6 +292,10 @@ gather_intrinsic_info(nir_intrinsic_instr *instr, nir_shader *shader,
 static void
 gather_tex_info(nir_tex_instr *instr, nir_shader *shader)
 {
+   if (shader->info.stage == MESA_SHADER_FRAGMENT &&
+       nir_tex_instr_has_implicit_derivative(instr))
+      shader->info.fs.needs_helper_invocations = true;
+
    switch (instr->op) {
    case nir_texop_tg4:
       shader->info.uses_texture_gather = true;
@@ -300,6 +312,13 @@ gather_alu_info(nir_alu_instr *instr, nir_shader *shader)
    case nir_op_fddx:
    case nir_op_fddy:
       shader->info.uses_fddx_fddy = true;
+      /* Fall through */
+   case nir_op_fddx_fine:
+   case nir_op_fddy_fine:
+   case nir_op_fddx_coarse:
+   case nir_op_fddy_coarse:
+      if (shader->info.stage == MESA_SHADER_FRAGMENT)
+         shader->info.fs.needs_helper_invocations = true;
       break;
    default:
       break;

src/compiler/shader_info.h

@@ -188,6 +188,14 @@ typedef struct shader_info {
       struct {
          bool uses_discard;
 
+         /**
+          * True if this fragment shader requires helper invocations.  This
+          * can be caused by the use of ALU derivative ops, texture
+          * instructions which do implicit derivatives, and the use of quad
+          * subgroup operations.
+          */
+         bool needs_helper_invocations;
+
          /**
           * Whether any inputs are declared with the "sample" qualifier.
           */