During HexFloat parsing, if exponent was too large, we would overflow
the signed integer being used to store its value. We now use an uint32_t
to avoid UB, then convert to int32_t when it's safe to do so.
Also error out if the input exponent is > INT_MAX - 127, which ensures
we will not wrap around and produce an invalid result when adding the
exponent bias of 127.
Bug: chromium:1240048
Bug: tint:1150
Change-Id: I1b57b2c965358b803ebb68ea70b76e759cdd3939
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/63120
Reviewed-by: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
17e83de54f