search for: _rotl16

...n't tried it on a recent clang version) and what I wondered was whether there was mileage in having an explicit intrinsic for rotation (like there is for bit counting, as in __builtin_clz and __builtin_ctz and so on). Microsoft's compiler has an explicit intrinsic in the form of _rotl8 and _rotl16 (IIRC -- this is from memory!). It would be nice to have a __builtin_rotl family in clang, in my opinion, but it would need back-end support from llvm. I would expect it to find use in code relating to hashing and cryptology. I know that the compiler *should* optimise uint32_t ror(uint32_t inpu...

*NOTE* IIRC compiling this with -O0 on x86-64 can yield the wrong result since clang will emit shifts and on intel shifts are mod the register size: ===== .section __TEXT,__text,regular,pure_instructions .globl _ror .align 4, 0x90 _ror: ## @ror .cfi_startproc ## BB#0: pushq %rbp Ltmp2: .cfi_def_cfa_offset 16 Ltmp3: .cfi_offset %rbp, -16 movq %rsp, %rbp

Nice! Clever compiler.. On 07/28/2012 08:55 PM, Michael Gottesman wrote: > I can get clang/llvm to emit a rotate instruction on x86-64 when compiling C by just using -Os and the rotate from Hacker's Delight i.e., > > ====== > #include<stdlib.h> > #include<stdint.h> > > uint32_t ror(uint32_t input, size_t rot_bits) > { > return (input>>