[llvm] r270885 - Do not rename registers that do not start an independent live range

[Evgenii Stepanov via llvm-commits]

It should be enough to build llvm with -DLLVM_USE_SANITIZER=Address
and run check-llvm. The bot also links LLVM with ASan-instrumented
libc++, but that probably would not be necessary.


On Fri, May 27, 2016 at 11:48 AM, Krzysztof Parzyszek
<kparzysz at codeaurora.org> wrote:
> Hi,
> It doesn't show why it fails, there is only "Exit Code: 1".  Do you have
> steps to reproduce this problem?
>
> -Krzysztof
>
>
>
> On 5/27/2016 1:15 PM, Evgenii Stepanov wrote:
>>
>> Hi,
>>
>> this test is failing on ASan:
>>
>> http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap/builds/11794/steps/check-llvm%20asan/logs/stdio
>>
>> On Thu, May 26, 2016 at 11:22 AM, Krzysztof Parzyszek via llvm-commits
>> <llvm-commits at lists.llvm.org> wrote:
>>>
>>> Author: kparzysz
>>> Date: Thu May 26 13:22:53 2016
>>> New Revision: 270885
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=270885&view=rev
>>> Log:
>>> Do not rename registers that do not start an independent live range
>>>
>>> Added:
>>>     llvm/trunk/test/CodeGen/MIR/Hexagon/
>>>     llvm/trunk/test/CodeGen/MIR/Hexagon/anti-dep-partial.mir
>>> Modified:
>>>     llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.cpp
>>>
>>> Modified: llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.cpp?rev=270885&r1=270884&r2=270885&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.cpp (original)
>>> +++ llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.cpp Thu May 26
>>> 13:22:53 2016
>>> @@ -787,6 +787,8 @@ unsigned AggressiveAntiDepBreaker::Break
>>>    DEBUG(dbgs() << '\n');
>>>  #endif
>>>
>>> +  BitVector RegAliases(TRI->getNumRegs());
>>> +
>>>    // Attempt to break anti-dependence edges. Walk the instructions
>>>    // from the bottom up, tracking information about liveness as we go
>>>    // to help determine which registers are available.
>>> @@ -898,6 +900,29 @@ unsigned AggressiveAntiDepBreaker::Break
>>>            }
>>>
>>>            if (AntiDepReg == 0) continue;
>>> +
>>> +          // If the definition of the anti-dependency register does not
>>> start
>>> +          // a new live range, bail out. This can happen if the anti-dep
>>> +          // register is a sub-register of another register whose live
>>> range
>>> +          // spans over PathSU. In such case, PathSU defines only a part
>>> of
>>> +          // the larger register.
>>> +          RegAliases.reset();
>>> +          for (MCRegAliasIterator AI(AntiDepReg, TRI, true);
>>> AI.isValid(); ++AI)
>>> +            RegAliases.set(*AI);
>>> +          for (SDep S : PathSU->Succs) {
>>> +            SDep::Kind K = S.getKind();
>>> +            if (K != SDep::Data && K != SDep::Output && K != SDep::Anti)
>>> +              continue;
>>> +            unsigned R = S.getReg();
>>> +            if (!RegAliases[R])
>>> +              continue;
>>> +            if (R == AntiDepReg || TRI->isSubRegister(AntiDepReg, R))
>>> +              continue;
>>> +            AntiDepReg = 0;
>>> +            break;
>>> +          }
>>> +
>>> +          if (AntiDepReg == 0) continue;
>>>          }
>>>
>>>          assert(AntiDepReg != 0);
>>>
>>> Added: llvm/trunk/test/CodeGen/MIR/Hexagon/anti-dep-partial.mir
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/MIR/Hexagon/anti-dep-partial.mir?rev=270885&view=auto
>>>
>>> ==============================================================================
>>> --- llvm/trunk/test/CodeGen/MIR/Hexagon/anti-dep-partial.mir (added)
>>> +++ llvm/trunk/test/CodeGen/MIR/Hexagon/anti-dep-partial.mir Thu May 26
>>> 13:22:53 2016
>>> @@ -0,0 +1,35 @@
>>> +# RUN: llc -march=hexagon -post-RA-scheduler -run-pass post-RA-sched %s
>>> 2>&1 -o /dev/null | FileCheck %s
>>> +
>>> +--- |
>>> +  declare void @check(i64, i32, i32, i64)
>>> +  define void @foo() {
>>> +    ret void
>>> +  }
>>> +...
>>> +
>>> +---
>>> +name: foo
>>> +tracksRegLiveness: true
>>> +allVRegsAllocated: true
>>> +body: |
>>> +  bb.0:
>>> +    successors:
>>> +    liveins: %r0, %r1, %d1, %d2, %r16, %r17, %r19, %r22, %r23
>>> +        %r2 = A2_add %r23, killed %r17
>>> +        %r6 = M2_mpyi %r16, %r16
>>> +        %r22 = M2_accii %r22, killed %r2, 2
>>> +        %r7 = A2_tfrsi 12345678
>>> +        %r3 = A2_tfr killed %r16
>>> +        %d2 = A2_tfrp killed %d0
>>> +        %r2 = L2_loadri_io %r29, 28
>>> +        %r2 = M2_mpyi killed %r6, killed %r2
>>> +        %r23 = S2_asr_i_r %r22, 31
>>> +        S2_storeri_io killed %r29, 0, killed %r7
>>> +        ; The anti-dependency on r23 between the first A2_add and the
>>> +        ; S2_asr_i_r was causing d11 to be renamed, while r22 remained
>>> +        ; unchanged. Check that the renaming of d11 does not happen.
>>> +        ; CHECK: d11
>>> +        %d0 = A2_tfrp killed %d11
>>> +        J2_call @check, implicit-def %d0, implicit-def %d1, implicit-def
>>> %d2, implicit %d0, implicit %d1, implicit %d2
>>> +...
>>> +
>>>
>>>
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