nir/algebraic: Detect missing f on F-strings

Missing f in other cases seems to be caught either elsewhere in the
script or by the C compiler.

Fixes: c49d6e0480 ("nir/algebraic: Elide range clamping of f2u sources")
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@intel.com>
(cherry picked from commit aba079b3af)

Conflicts:
	src/compiler/nir/nir_algebraic.py

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39462>

.pick_status.json

@@ -5144,7 +5144,7 @@
         "description": "nir/algebraic: Detect missing f on F-strings",
         "nominated": true,
         "nomination_type": 2,
-        "resolution": 0,
+        "resolution": 1,
         "main_sha": null,
         "because_sha": "c49d6e048087a3a6fd17ca56c1e887c697624adf",
         "notes": null

src/compiler/nir/nir_algebraic.py

@@ -107,6 +107,9 @@ class SearchExpression(object):
       self.sources = expr[1:]
       self.ignore_exact = False
 
+      assert '{' not in self.opcode, \
+          'Malformed opcode name \"{}\".'.format(self.opcode)
+
    @staticmethod
    def create(val):
       if isinstance(val, tuple):