Bugfix examples/uint63z/prims.c #5
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…gfixes) Here, the sub-expression "(1 << i) is interpreted as shifting a signed integer by the unsigned integer value i, according to the ISO/IEC C standard [11, §6.4.4.1]. But when the size of value is 8 byte, i.e. 64 bits, which is the default case, the expression “unsigned int i = sizeof(value) * 8 - 1” evaluates to “unsigned int i = 63”. Thus, in the first iteration of the loop, the integer value 1 (which has 32 bits) is shifted left by 63 bits which is a shift over- flow. However, no error is provoked when compiling the file with the GCC for user space with the proposed compilation flags. But when adding the compiler flag -fsanitize=shift which adds runtime instrumentation for recognising shift overflows and is used by default for compiling Kernel modules, a runtime error (shift-out-of-bounds) is generated. The solution is here to add the suffix “ULL” to the integer constant 1. [11]: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf
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…gfixes)
Here, the sub-expression "(1 << i) is interpreted as shifting a signed integer by the unsigned integer value i, according to the ISO/IEC C standard [11, §6.4.4.1]. But when the size of value is 8 byte, i.e. 64 bits, which is the default case, the expression “unsigned int i = sizeof(value) * 8 - 1” evaluates to “unsigned int i = 63”. Thus, in the first iteration of the loop, the integer value 1 (which has 32 bits) is shifted left by 63 bits which is a shift over- flow. However, no error is provoked when compiling the file with the GCC for user space with the proposed compilation flags. But when adding the compiler flag -fsanitize=shift which adds runtime instrumentation for recognising shift overflows and is used by default for compiling Kernel modules, a runtime error (shift-out-of-bounds) is generated. The solution is here to add the suffix “ULL” to the integer constant 1.