audk/IntelFspWrapperPkg
Hao Wu bcee1b9f17 IntelFspWrapperPkg: Refine casting expression result to bigger size
There are cases that the operands of an expression are all with rank less
than UINT64/INT64 and the result of the expression is explicitly cast to
UINT64/INT64 to fit the target size.

An example will be:
UINT32 a,b;
// a and b can be any unsigned int type with rank less than UINT64, like
// UINT8, UINT16, etc.
UINT64 c;
c = (UINT64) (a + b);

Some static code checkers may warn that the expression result might
overflow within the rank of "int" (integer promotions) and the result is
then cast to a bigger size.

The commit refines codes by the following rules:
1). When the expression is possible to overflow the range of unsigned int/
int:
c = (UINT64)a + b;

2). When the expression will not overflow within the rank of "int", remove
the explicit type casts:
c = a + b;

3). When the expression will be cast to pointer of possible greater size:
UINT32 a,b;
VOID *c;
c = (VOID *)(UINTN)(a + b); --> c = (VOID *)((UINTN)a + b);

4). When one side of a comparison expression contains only operands with
rank less than UINT32:
UINT8 a;
UINT16 b;
UINTN c;
if ((UINTN)(a + b) > c) {...} --> if (((UINT32)a + b) > c) {...}

For rule 4), if we remove the 'UINTN' type cast like:
if (a + b > c) {...}
The VS compiler will complain with warning C4018 (signed/unsigned
mismatch, level 3 warning) due to promoting 'a + b' to type 'int'.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
2017-03-06 14:33:23 +08:00
..
FspInitPei IntelFspWrapperPkg: Fix typos in comments 2016-10-24 09:26:30 +08:00
FspNotifyDxe IntelFspWrapperPkg: Refine casting expression result to bigger size 2017-03-06 14:33:23 +08:00
FspWrapperSecCore IntelFspWrapperPkg: Fix typos in comments 2016-10-24 09:26:30 +08:00
Include IntelFspWrapperPkg update for FSP1.1 2015-04-23 08:53:39 +00:00
Library IntelFspWrapperPkg: Refine casting expression result to bigger size 2017-03-06 14:33:23 +08:00
Contributions.txt */Contributions.txt: Update example email address 2015-02-03 17:29:14 +00:00
IntelFspWrapperPkg.dec Add dual FSP binaries support. 2015-04-29 03:50:20 +00:00
IntelFspWrapperPkg.dsc IntelFspWrapperPkg DSC: Add build option to disable deprecated APIs 2016-08-08 11:00:06 +08:00
License.txt IntelFspWrapperPkg: Add missing License.txt. 2016-07-26 10:52:06 +08:00