ubsan: signed integer multiply overflow
Alan Modra
amodra@gmail.com
Sat Jan 1 05:18:05 GMT 2022
9223371018427387904 * 2 cannot be represented in type 'long', yes, but
we don't care.
* expr.c (expr): Avoid signed overflow.
diff --git a/gas/expr.c b/gas/expr.c
index 03caa91f4d1..618927a605f 100644
--- a/gas/expr.c
+++ b/gas/expr.c
@@ -1959,7 +1959,12 @@ expr (int rankarg, /* Larger # is higher rank. */
switch (op_left)
{
default: goto general;
- case O_multiply: resultP->X_add_number *= v; break;
+ case O_multiply:
+ /* Do the multiply as unsigned to silence ubsan. The
+ result is of course the same when we throw away high
+ bits of the result. */
+ resultP->X_add_number *= (valueT) v;
+ break;
case O_divide: resultP->X_add_number /= v; break;
case O_modulus: resultP->X_add_number %= v; break;
case O_left_shift:
--
Alan Modra
Australia Development Lab, IBM
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