glsl: Remove unused as_rvalue_to_saturate().

This is not where saturate recognition happens.  Dead code since
5598458e69 ("i965/vec4: Remove try_emit_saturate") in 2014!

Acked-by: Timothy Arceri <tarceri@itsqueeze.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21475>

src/compiler/glsl/ir.cpp

@@ -2291,63 +2291,6 @@ reparent_ir(exec_list *list, void *mem_ctx)
    }
 }
 
-
-static ir_rvalue *
-try_min_one(ir_rvalue *ir)
-{
-   ir_expression *expr = ir->as_expression();
-
-   if (!expr || expr->operation != ir_binop_min)
-      return NULL;
-
-   if (expr->operands[0]->is_one())
-      return expr->operands[1];
-
-   if (expr->operands[1]->is_one())
-      return expr->operands[0];
-
-   return NULL;
-}
-
-static ir_rvalue *
-try_max_zero(ir_rvalue *ir)
-{
-   ir_expression *expr = ir->as_expression();
-
-   if (!expr || expr->operation != ir_binop_max)
-      return NULL;
-
-   if (expr->operands[0]->is_zero())
-      return expr->operands[1];
-
-   if (expr->operands[1]->is_zero())
-      return expr->operands[0];
-
-   return NULL;
-}
-
-ir_rvalue *
-ir_rvalue::as_rvalue_to_saturate()
-{
-   ir_expression *expr = this->as_expression();
-
-   if (!expr)
-      return NULL;
-
-   ir_rvalue *max_zero = try_max_zero(expr);
-   if (max_zero) {
-      return try_min_one(max_zero);
-   } else {
-      ir_rvalue *min_one = try_min_one(expr);
-      if (min_one) {
-	 return try_max_zero(min_one);
-      }
-   }
-
-   return NULL;
-}
-
-
 unsigned
 vertices_per_prim(GLenum prim)
 {

src/compiler/glsl/ir.h

@@ -230,8 +230,6 @@ public:
    virtual ir_constant *constant_expression_value(void *mem_ctx,
                                                   struct hash_table *variable_context = NULL);
 
-   ir_rvalue *as_rvalue_to_saturate();
-
    virtual bool is_lvalue(const struct _mesa_glsl_parse_state * = NULL) const
    {
       return false;