[llvm-commits] [LLVM, loop-unswitch, bugfix for #11429] Wrong behaviour for switches.

[Stepan Dyatkovskiy]

ping.

-Stepan.

Stepan Dyatkovskiy wrote:
> ping.
>
> -Stepan.
>
> Stepan Dyatkovskiy wrote:
>> ping.
>>
>> -Stepan
>>
>> Stepan Dyatkovskiy wrote:
>>> Hi all. Please find the patch in attachment for review. Regression tests
>>> are attached in separated patch.
>>>
>>> Short tests description:
>>>
>>> 2011-11-18-SimpleSwitch.ll
>>> Check simple that simple switch will totally unswitched:
>>>
>>> for (...)
>>> switch(c) {
>>> case 0: inc(); break;
>>> case 1: dec(); break;
>>> default: goto loop_exit;
>>> }
>>>
>>> loop_exit:
>>> ...
>>>
>>> Result of processing should be 2 additional loops for c == 0 and for c
>>> == 1.
>>>
>>>
>>> 2011-11-18-TwoSwitches.ll
>>> Check that second switch will unswitched too. Check that switches will
>>> not unswitched again in new loop:
>>>
>>> Initially we have the next:
>>>
>>> for (...) {
>>> switch(c) {
>>> case 0: inc(); break;
>>> }
>>> switch(d) {
>>> case 0: inc(); break;
>>> }
>>> }
>>>
>>> After optimization we should got 3 additional loops: when (c == 0&&   d
>>> == 0), when (c == 0&&   d != 0) and when (c != 0&&   d == 0). Original
>>> loop will activated for (c != 0&&   d != 0):
>>>
>>> if (c == 0&&   d == 0) {
>>> for (...) ... // All is clear here. Two "switch(0)" instructions.
>>> } else if (c == 0&&   d != 0) {
>>> for (...) {
>>> switch (0) { // c == 0
>>> case 0: inc(); break;
>>> }
>>> switch (d) {
>>> case 0: goto unreachable; // CHECK: That it will not unswitched
>>> // again, since it looks "trivial",
>>> // see LoopUnswitch::IsTrivialUnswitchCondition
>>> }
>>> }
>>> } else if (c != 0&&   d == 0) {
>>> // the same...
>>> ...
>>> } else { // if (c != 0&&   d != 0)
>>> // Original totally unswitched loop:
>>> switch (c) {
>>> case 0: goto unreachable;
>>> }
>>> switch (d) {
>>> case 0: goto unreachable;
>>> }
>>> }
>>>
>>> Stepan.
>>>
>>>
>>> _______________________________________________
>>> llvm-commits mailing list
>>> llvm-commits at cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits