decodetree: Propagate return value from translate subroutines

Allow the translate subroutines to return false for invalid insns.

At present we can of course invoke an invalid insn exception from within
the translate subroutine, but in the short term this consolidates code.
In the long term it would allow the decodetree language to support
overlapping patterns for ISA extensions.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180227232618.2908-1-richard.henderson@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/scripts/decodetree.py b/scripts/decodetree.py
index 6a33f8f8dd99bce33d4732cde59736a11d7bee79..41301c84aa1ff76bda52c0378efbed7daede0d50 100755 (executable)
--- a/scripts/decodetree.py
+++ b/scripts/decodetree.py
@@ -461,7 +461,7 @@ class Pattern(General):
         global translate_prefix
         output('typedef ', self.base.base.struct_name(),
                ' arg_', self.name, ';\n')
-        output(translate_scope, 'void ', translate_prefix, '_', self.name,
+        output(translate_scope, 'bool ', translate_prefix, '_', self.name,
                '(DisasContext *ctx, arg_', self.name,
                ' *a, ', insntype, ' insn);\n')
 
@@ -474,9 +474,8 @@ class Pattern(General):
             output(ind, self.base.extract_name(), '(&u.f_', arg, ', insn);\n')
         for n, f in self.fields.items():
             output(ind, 'u.f_', arg, '.', n, ' = ', f.str_extract(), ';\n')
-        output(ind, translate_prefix, '_', self.name,
+        output(ind, 'return ', translate_prefix, '_', self.name,
                '(ctx, &u.f_', arg, ', insn);\n')
-        output(ind, 'return true;\n')
 # end Pattern