Re: negative latencies

2014-05-25 Thread shmeel gutl
On 23-May-14 01:59 PM, Bernd Schmidt wrote: On 05/23/2014 10:07 AM, shmeel gutl wrote: Exposed pipeline is not my problem. Negative latency is my problem. I don't see negative latency for c6x, not in unit reservations and not in adjust cost. Did I miss something? You just need to model it

Re: negative latencies

2014-05-25 Thread shmeel gutl
On 23-May-14 05:20 PM, Vladimir Makarov wrote: On 2014-05-23, 3:49 AM, shmeel gutl wrote: On 21-May-14 06:30 PM, Vladimir Makarov wrote: I am just curious what happens when you put insn2, insn1. and insn2 uses a result of insn1 in 6 cycles and insn1 producing the result in 3 cycles, but

Re: negative latencies

2014-05-23 Thread shmeel gutl
On 21-May-14 06:30 PM, Vladimir Makarov wrote: I am just curious what happens when you put insn2, insn1. and insn2 uses a result of insn1 in 6 cycles and insn1 producing the result in 3 cycles, but there are not ready functional units (e.g. arithmentic units) necessary for insn1 for 4 or

Re: negative latencies

2014-05-23 Thread shmeel gutl
On 22-May-14 07:21 PM, Bernd Schmidt wrote: On 05/21/2014 05:30 PM, Vladimir Makarov wrote: On 2014-05-20, 5:18 PM, shmeel gutl wrote: The problem that I see is that the haifa scheduler schedules one cycle at a time, in a forward order, by picking from a list of instructions that can be

Re: negative latencies

2014-05-23 Thread Bernd Schmidt
On 05/23/2014 10:07 AM, shmeel gutl wrote: Exposed pipeline is not my problem. Negative latency is my problem. I don't see negative latency for c6x, not in unit reservations and not in adjust cost. Did I miss something? You just need to model it differently. Rather than saying instruction A

Re: negative latencies

2014-05-23 Thread Vladimir Makarov
On 2014-05-23, 3:49 AM, shmeel gutl wrote: On 21-May-14 06:30 PM, Vladimir Makarov wrote: I am just curious what happens when you put insn2, insn1. and insn2 uses a result of insn1 in 6 cycles and insn1 producing the result in 3 cycles, but there are not ready functional units (e.g.

Re: negative latencies

2014-05-22 Thread Bernd Schmidt
On 05/21/2014 05:30 PM, Vladimir Makarov wrote: On 2014-05-20, 5:18 PM, shmeel gutl wrote: The problem that I see is that the haifa scheduler schedules one cycle at a time, in a forward order, by picking from a list of instructions that can be scheduled without delays. So, in the above example,

Re: negative latencies

2014-05-21 Thread Vladimir Makarov
On 2014-05-20, 5:18 PM, shmeel gutl wrote: On 20-May-14 06:13 PM, Vladimir Makarov wrote: On 05/19/2014 02:13 AM, shmeel gutl wrote: Are there hooks in gcc to deal with negative latencies? In other words, an architecture that permits an instruction to use a result from an instruction that will

Re: negative latencies

2014-05-20 Thread Vladimir Makarov
On 05/19/2014 02:13 AM, shmeel gutl wrote: Are there hooks in gcc to deal with negative latencies? In other words, an architecture that permits an instruction to use a result from an instruction that will be issued later. Could you explain more on *an example* what are you trying to achieve

Re: negative latencies

2014-05-20 Thread shmeel gutl
On 20-May-14 06:13 PM, Vladimir Makarov wrote: On 05/19/2014 02:13 AM, shmeel gutl wrote: Are there hooks in gcc to deal with negative latencies? In other words, an architecture that permits an instruction to use a result from an instruction that will be issued later. Could you explain more

Re: negative latencies

2014-05-19 Thread Andrew Pinski
On Sun, May 18, 2014 at 11:13 PM, shmeel gutl shmeelg...@shmuelhome.mine.nu wrote: Are there hooks in gcc to deal with negative latencies? In other words, an architecture that permits an instruction to use a result from an instruction that will be issued later. Do you mean bypasses? If so

Re: negative latencies

2014-05-19 Thread shmeel gutl
On 19-May-14 09:39 AM, Andrew Pinski wrote: On Sun, May 18, 2014 at 11:13 PM, shmeel gutl shmeelg...@shmuelhome.mine.nu wrote: Are there hooks in gcc to deal with negative latencies? In other words, an architecture that permits an instruction to use a result from an instruction that will be

RE: negative latencies

2014-05-19 Thread Ajit Kumar Agarwal
Makarov Subject: Re: negative latencies On 19-May-14 09:39 AM, Andrew Pinski wrote: On Sun, May 18, 2014 at 11:13 PM, shmeel gutl shmeelg...@shmuelhome.mine.nu wrote: Are there hooks in gcc to deal with negative latencies? In other words, an architecture that permits an instruction to use a result

Re: negative latencies

2014-05-19 Thread shmeel gutl
Of shmeel gutl Sent: Monday, May 19, 2014 12:23 PM To: Andrew Pinski Cc: gcc@gcc.gnu.org; Vladimir Makarov Subject: Re: negative latencies On 19-May-14 09:39 AM, Andrew Pinski wrote: On Sun, May 18, 2014 at 11:13 PM, shmeel gutl shmeelg...@shmuelhome.mine.nu wrote: Are there hooks in gcc to deal