ShellPkg: 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: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>

diff --git a/ShellPkg/Library/UefiShellDebug1CommandsLib/HexEdit/BufferImage.c b/ShellPkg/Library/UefiShellDebug1CommandsLib/HexEdit/BufferImage.c
index 68d2443d2e5ed7f57dfb2fc7782fd2d74d81221d..1048ecd41593a7d256ed187f88fbbaffd3493eb3 100644 (file)
--- a/ShellPkg/Library/UefiShellDebug1CommandsLib/HexEdit/BufferImage.c
+++ b/ShellPkg/Library/UefiShellDebug1CommandsLib/HexEdit/BufferImage.c
@@ -2,7 +2,7 @@
   Defines HBufferImage - the view of the file that is visible at any point,\r
   as well as the event handlers for editing the file\r
   \r
-  Copyright (c) 2005 - 2014, Intel Corporation. All rights reserved. <BR>\r
+  Copyright (c) 2005 - 2017, Intel Corporation. All rights reserved. <BR>\r
   This program and the accompanying materials\r
   are licensed and made available under the terms and conditions of the BSD License\r
   which accompanies this distribution.  The full text of the license may be found at\r
@@ -1108,15 +1108,15 @@ HBufferImageCharToHex (
   // change the character to hex\r
   //\r
   if (Char >= L'0' && Char <= L'9') {\r
-    return (INTN) (Char - L'0');\r
+    return (Char - L'0');\r
   }\r
 \r
   if (Char >= L'a' && Char <= L'f') {\r
-    return (INTN) (Char - L'a' + 10);\r
+    return (Char - L'a' + 10);\r
   }\r
 \r
   if (Char >= L'A' && Char <= L'F') {\r
-    return (INTN) (Char - L'A' + 10);\r
+    return (Char - L'A' + 10);\r
   }\r
 \r
   return -1;\r

diff --git a/ShellPkg/Library/UefiShellLib/UefiShellLib.c b/ShellPkg/Library/UefiShellLib/UefiShellLib.c
index 536db3c80599ff21e7798035e789b061c120c31a..55e8a67ac43cebe3ce1e41c62b066d35601098d0 100644 (file)
--- a/ShellPkg/Library/UefiShellLib/UefiShellLib.c
+++ b/ShellPkg/Library/UefiShellLib/UefiShellLib.c
@@ -3,7 +3,7 @@
 \r
   (C) Copyright 2016 Hewlett Packard Enterprise Development LP<BR>\r
   Copyright 2016 Dell Inc.\r
-  Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>\r
+  Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>\r
   This program and the accompanying materials\r
   are licensed and made available under the terms and conditions of the BSD License\r
   which accompanies this distribution.  The full text of the license may be found at\r
@@ -3755,7 +3755,7 @@ InternalShellHexCharToUintn (
     return Char - L'0';\r
   }\r
 \r
-  return (UINTN) (10 + InternalShellCharToUpper (Char) - L'A');\r
+  return (10 + InternalShellCharToUpper (Char) - L'A');\r
 }\r
 \r
 /**\r