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Fix signed left shift in vm_loop().

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Signed left shift operations are undefined in C. Add constants for the minimum/maximum integer value which are already shifted. Technically, the constant for the shifted maximum value is not required, adding it for consistency/increased readability.

The bug was detected by -Wshift-negative-value both with GCC 6.x and Clang.

This fixes #1174.

JerryScript-DCO-1.0-Signed-off-by: Tilmann Scheller t.scheller@samsung.com
This commit is contained in:
Tilmann Scheller 2016-07-05 21:11:54 +02:00
parent 5f7997d2d0
commit fb9b4dd807
2 changed files with 14 additions and 6 deletions
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16
jerry-core/ecma/base/ecma-globals.h
View File

@ -143,20 +143,28 @@ typedef int32_t ecma_integer_value_t;
* Maximum integer number for an ecma value
*/
#if CONFIG_ECMA_NUMBER_TYPE == CONFIG_ECMA_NUMBER_FLOAT32
#define ECMA_INTEGER_NUMBER_MAX 0x7fffff
#define ECMA_INTEGER_NUMBER_MAX 0x7fffff
#define ECMA_INTEGER_NUMBER_MAX_SHIFTED 0x7fffff0
#else /* CONFIG_ECMA_NUMBER_TYPE != CONFIG_ECMA_NUMBER_FLOAT32 */
#define ECMA_INTEGER_NUMBER_MAX 0x7ffffff
#define ECMA_INTEGER_NUMBER_MAX 0x7ffffff
#define ECMA_INTEGER_NUMBER_MAX_SHIFTED 0x7ffffff0
#endif /* CONFIG_ECMA_NUMBER_TYPE == CONFIG_ECMA_NUMBER_FLOAT32 */
/**
* Minimum integer number for an ecma value
*/
#if CONFIG_ECMA_NUMBER_TYPE == CONFIG_ECMA_NUMBER_FLOAT32
#define ECMA_INTEGER_NUMBER_MIN -0x7fffff
#define ECMA_INTEGER_NUMBER_MIN -0x7fffff
#define ECMA_INTEGER_NUMBER_MIN_SHIFTED -0x7fffff0
#else /* CONFIG_ECMA_NUMBER_TYPE != CONFIG_ECMA_NUMBER_FLOAT32 */
#define ECMA_INTEGER_NUMBER_MIN -0x8000000
#define ECMA_INTEGER_NUMBER_MIN -0x8000000
#define ECMA_INTEGER_NUMBER_MIN_SHIFTED (-0x7fffffff - 1) /* -0x80000000 */
#endif /* CONFIG_ECMA_NUMBER_TYPE == CONFIG_ECMA_NUMBER_FLOAT32 */
#if ECMA_DIRECT_SHIFT != 4
#error "Please update ECMA_INTEGER_NUMBER_MIN/MAX_SHIFTED according to the new value of ECMA_DIRECT_SHIFT."
#endif
/**
* Checks whether the integer number is in the integer number range.
*/

4
jerry-core/vm/vm.c
View File

@ -1215,12 +1215,12 @@ vm_loop (vm_frame_ctx_t *frame_ctx_p) /**< frame context */
if (opcode_flags & VM_OC_DECREMENT_OPERATOR_FLAG)
{
if (int_value > (ECMA_INTEGER_NUMBER_MIN << ECMA_DIRECT_SHIFT))
if (int_value > ECMA_INTEGER_NUMBER_MIN_SHIFTED)
{
int_increase = -(1 << ECMA_DIRECT_SHIFT);
}
}
else if (int_value < (ECMA_INTEGER_NUMBER_MAX << ECMA_DIRECT_SHIFT))
else if (int_value < ECMA_INTEGER_NUMBER_MAX_SHIFTED)
{
int_increase = 1 << ECMA_DIRECT_SHIFT;
}