https://bugs.llvm.org/show_bug.cgi?id=48769
Bug ID: 48769
Summary: Failure to optimize __builtin_mul_overflow pattern
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Scalar Optimizations
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
int f1(unsigned x, unsigned y)
{
unsigned int r = x * y;
return x && ((int)r / (int)x) != (int)y;
}
This can be optimized to :
int f2(unsigned x, unsigned y)
{
int res;
return __builtin_mul_overflow((int)x, (int)y, &res);
}
This optimization is done by GCC, but not by LLVM.
See also comparison here : https://godbolt.org/z/f9Yv9c
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