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I'm trying to override some standard library functions using LD_PRELOAD. However, I notice that my version is never called for some functions, for example, the gettimeofday one. I suspect gcc uses an inbuilt version for some of these functions.
Is there a way I can tell gcc to not use inbuilt standard library functions.
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__builtin_clz(x): Counts the leading number of zeros of the integer(long/long long).
Built-in Function: int __builtin_ffs (int x) Returns one plus the index of the least significant 1-bit of x , or if x is zero, returns zero. Built-in Function: int __builtin_clz (unsigned int x) Returns the number of leading 0-bits in x , starting at the most significant bit position.
Tells the compiler not to use generic (non-Arm specific) handling and optimization of standard C and C++ library functions and operators, for example for the printf() , strlen() , and malloc() functions from the C standard library, or for the new and delete operators from the C++ standard library.
__builtin_popcount(x) is a function in C++ returns the number of 1-bits set in an int x. In fact, "popcount" stands for "population count," so this is a function to determine how "populated" an integer is.
Use the gcc switch -fno-builtin. Quoting from the gcc manual:
-fno-builtin
Don't recognize built-in functions that do not begin with `_builtin' as prefix.
More details: http://gcc.gnu.org/onlinedocs/gcc-3.0/gcc_3.html#SEC7
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