https://bugs.llvm.org/show_bug.cgi?id=45715
Bug ID: 45715
Summary: Failure to recognize bswap.i64 pattern
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: gabrav...@gmail.com
CC: llvm-bugs@lists.llvm.org
uint64_t swap64(uint64_t x)
{
return __builtin_bswap32(x >> 32) | ((uint64_t)__builtin_bswap32(x) << 32);
}
This is equivalent to `__builtin_bswap64(x)`. GCC does this transformation, but
only if `__builtin_bswap32` is replaced by a function equivalent to it (i.e.
that is recognized by GCC as equivalent to `__builtin_bswap32`). It would be
nice if LLVM could recognize this as equivalent to `__builtin_bswap64`
Comparison here : https://godbolt.org/z/gtJQdM
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