decodetree: Infer argument set before inferring format

Failure to confirm an argument set first may result in
the selection of a format which leaves extra arguments
to be filled in by the pattern.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20250723165458.3509150-4-peter.maydell@linaro.org
Message-id: 20250722183343.273533-1-richard.henderson@linaro.org
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Tested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

scripts/decodetree.py

@@ -1016,9 +1016,12 @@ def infer_format(arg, fieldmask, flds, width):
         else:
             var_flds[n] = c
 
+    if not arg:
+        arg = infer_argument_set(flds)
+
     # Look for an existing format with the same argument set and fields
     for fmt in formats.values():
-        if arg and fmt.base != arg:
+        if fmt.base != arg:
             continue
         if fieldmask != fmt.fieldmask:
             continue
@@ -1029,8 +1032,6 @@ def infer_format(arg, fieldmask, flds, width):
         return (fmt, const_flds)
 
     name = decode_function + '_Fmt_' + str(len(formats))
-    if not arg:
-        arg = infer_argument_set(flds)
 
     fmt = Format(name, 0, arg, 0, 0, 0, fieldmask, var_flds, width)
     formats[name] = fmt

tests/decode/meson.build

@@ -41,6 +41,7 @@ succ_tests = [
     'succ_argset_type1.decode',
     'succ_function.decode',
     'succ_ident1.decode',
+    'succ_infer1.decode',
     'succ_named_field.decode',
     'succ_pattern_group_nest1.decode',
     'succ_pattern_group_nest2.decode',

tests/decode/succ_infer1.decode

@@ -0,0 +1,4 @@
+&rprr_load      rd pg rn rm dtype nreg
+@rprr_load      .... .... ... rm:5 ... pg:3 rn:5 rd:5            &rprr_load
+
+LD1Q            1100 0100 000 rm:5 101 pg:3 rn:5 rd:5