MdeModulePkg: 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: Feng Tian <feng.tian@intel.com>
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@@ -1,7 +1,7 @@
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/** @file
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Contains code that implements the virtual machine.
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Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR>
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Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
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This program and the accompanying materials
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are licensed and made available under the terms and conditions of the BSD License
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which accompanies this distribution. The full text of the license may be found at
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@@ -2867,7 +2867,7 @@ ExecutePOPn (
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if (OPERAND1_INDIRECT (Operands)) {
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VmWriteMemN (VmPtr, (UINTN) (VmPtr->Gpr[OPERAND1_REGNUM (Operands)] + Index16), DataN);
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} else {
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VmPtr->Gpr[OPERAND1_REGNUM (Operands)] = (INT64) (UINT64) ((UINTN) DataN + Index16);
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VmPtr->Gpr[OPERAND1_REGNUM (Operands)] = (INT64) (UINT64) (UINTN) (DataN + Index16);
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}
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return EFI_SUCCESS;
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@@ -3592,7 +3592,7 @@ ExecuteSUB (
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if ((*VmPtr->Ip & DATAMANIP_M_64) != 0) {
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return (UINT64) ((INT64) ((INT64) Op1 - (INT64) Op2));
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} else {
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return (UINT64) ((INT64) ((INT32) Op1 - (INT32) Op2));
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return (UINT64) ((INT64) ((INT32) ((INT32) Op1 - (INT32) Op2)));
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}
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}
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@@ -3620,7 +3620,7 @@ ExecuteMUL (
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if ((*VmPtr->Ip & DATAMANIP_M_64) != 0) {
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return MultS64x64 ((INT64)Op1, (INT64)Op2);
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} else {
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return (UINT64) ((INT64) ((INT32) Op1 * (INT32) Op2));
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return (UINT64) ((INT64) ((INT32) ((INT32) Op1 * (INT32) Op2)));
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}
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}
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@@ -3648,7 +3648,7 @@ ExecuteMULU (
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if ((*VmPtr->Ip & DATAMANIP_M_64) != 0) {
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return MultU64x64 (Op1, Op2);
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} else {
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return (UINT64) ((UINT32) Op1 * (UINT32) Op2);
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return (UINT64) ((UINT32) ((UINT32) Op1 * (UINT32) Op2));
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}
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}
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