commit 2decfc95583dc28add69810eaca6ada7b4b44d3a
author Richard Henderson <richard.henderson@linaro.org> Tue Mar 05 15:34:41 2019 -0800
committer Richard Henderson <richard.henderson@linaro.org> Tue Mar 12 09:46:58 2019 -0700
tree 718b5b36ee3787742d9c30f344922f2bc802ae44
parent 71ecf79bf40db20237a3cfc01cc407cc4cad8817

decodetree: Properly diagnose fields overflowing an insn

Previously this would result in an exception for shifting
the field mask by a negative number.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

scripts/decodetree.py

diff --git a/scripts/decodetree.py b/scripts/decodetree.py
index ac158b4..aa790b5 100755
--- a/scripts/decodetree.py
+++ b/scripts/decodetree.py
@@ -622,6 +622,8 @@
                 sign = True
                 flen = flen[1:]
             shift = int(flen, 10)
+            if shift + width > insnwidth:
+                error(lineno, 'field {0} exceeds insnwidth'.format(fname))
             f = Field(sign, insnwidth - width - shift, shift)
             flds = add_field(lineno, flds, fname, f)
             fixedbits <<= shift