Re: [PATCH 0/6] aarch64: Implement TImode comparisons

2020-03-19 Thread Wilco Dijkstra
Hi Richard, > Any compare can be done in at most 2 instructions: > > void doit(void); > void f(long long a) > { > if (a <= 1) > doit(); > } > > f: > cmp r0, #2 > sbcs    r3, r1, #0 > blt .L4 > Well, this one requires that you be able to add 1 to an in

Re: [PATCH 0/6] aarch64: Implement TImode comparisons

2020-03-19 Thread Richard Henderson via Gcc-patches
On 3/19/20 8:47 AM, Wilco Dijkstra wrote: > Hi Richard, > > Thanks for these patches - yes TI mode expansions can certainly be improved! > So looking at your expansions for signed compares, why not copy the optimal > sequence from 32-bit Arm? > > Any compare can be done in at most 2 instructions:

Re: [PATCH 0/6] aarch64: Implement TImode comparisons

2020-03-19 Thread Wilco Dijkstra
Hi Richard, Thanks for these patches - yes TI mode expansions can certainly be improved! So looking at your expansions for signed compares, why not copy the optimal sequence from 32-bit Arm? Any compare can be done in at most 2 instructions: void doit(void); void f(long long a) { if (a <= 1)