Add the below flags, they are needed in -O2:
-fno-delete-null-pointer-checks:
* tells the compiler NOT to assume that null pointer deference does
not exist.
* Without this flag, below case cannot be detected:
a pointer might point to nullsometime during run-time and if there
is no validation for that pointer, it will cause the program to crash.
Since we don’t receive an error message saying that a pointer is
pointing to null, we will have a hard time trying to find the problem.
-fwrapv:
* tells the compiler that signed overflow always wraps.
* Without this flag, x + 10 > x will always be true for signed x.
With the flag, x + 10 > x is not always be true, as the overflow is
defined for x, and it could wrap.
Tracked-On: #4194
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Reviewed-by: Yonghua Huang <yonghua.huang@intel.com>
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