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author | Hao Wu <hao.a.wu@intel.com> | 2017-02-17 11:54:10 +0800 |
---|---|---|
committer | Hao Wu <hao.a.wu@intel.com> | 2017-03-06 14:33:26 +0800 |
commit | 8491e302e1450db96822838a83c283962c6a35f7 (patch) | |
tree | a0199f553b9a2d03e8b5f2fba6324c7328e326d4 /UefiCpuPkg/CpuIo2Dxe/CpuIo2Dxe.c | |
parent | 3ee1680978922a6542d58a1d33b346d49ab80c56 (diff) | |
download | edk2-8491e302e1450db96822838a83c283962c6a35f7.tar.gz edk2-8491e302e1450db96822838a83c283962c6a35f7.tar.bz2 edk2-8491e302e1450db96822838a83c283962c6a35f7.zip |
UefiCpuPkg: 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: Jeff Fan <jeff.fan@intel.com>
Diffstat (limited to 'UefiCpuPkg/CpuIo2Dxe/CpuIo2Dxe.c')
-rw-r--r-- | UefiCpuPkg/CpuIo2Dxe/CpuIo2Dxe.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/UefiCpuPkg/CpuIo2Dxe/CpuIo2Dxe.c b/UefiCpuPkg/CpuIo2Dxe/CpuIo2Dxe.c index 60f4bbc1fd..d19349d4b0 100644 --- a/UefiCpuPkg/CpuIo2Dxe/CpuIo2Dxe.c +++ b/UefiCpuPkg/CpuIo2Dxe/CpuIo2Dxe.c @@ -1,7 +1,7 @@ /** @file
Produces the CPU I/O 2 Protocol.
-Copyright (c) 2009 - 2012, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2009 - 2017, Intel Corporation. All rights reserved.<BR>
Copyright (c) 2017, AMD Incorporated. All rights reserved.<BR>
This program and the accompanying materials
@@ -141,7 +141,7 @@ CpuIoCheckParameter ( //
// Check to see if Address is aligned
//
- if ((Address & (UINT64)(mInStride[Width] - 1)) != 0) {
+ if ((Address & ((UINT64)mInStride[Width] - 1)) != 0) {
return EFI_UNSUPPORTED;
}
|