nir/algebraic: add support for conditional helper functions to expressions

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/compiler/nir/nir_search.c

@@ -263,6 +263,9 @@ match_expression(const nir_search_expression *expr, nir_alu_instr *instr,
                  unsigned num_components, const uint8_t *swizzle,
                  struct match_state *state)
 {
+   if (expr->cond && !expr->cond(instr))
+      return false;
+
    if (instr->op != expr->opcode)
       return false;