[llvm] r249431 - This patch builds on top of D13378 to handle constant condition.

[Sanjoy Das via llvm-commits]

I just checked in D13461 -- can you try un-reverting this change now and see if still crashes?

I really should have checked in D13461 early yesterday, sorry!

-- Sanjoy

Sanjoy Das wrote:
> I'm pretty sure that the crash is fixed by this: http://reviews.llvm.org/D13461 -- indvars RAUW'ed a LCSSA phi with a
> use outside the loop.
>
> Mehdi Amini via llvm-commits wrote:
>>
>>> On Oct 7, 2015, at 2:06 AM, James Molloy <james at jamesmolloy.co.uk <mailto:james at jamesmolloy.co.uk>> wrote:
>>>
>>> Hi Mehdi,
>>>
>>> I've reverted this in r249528 as it was causing failures in all our internal builders and here too:
>>> http://lab.llvm.org:8011/builders/clang-native-arm-lnt/builds/14453
>>>
>>> Apologies,
>>
>> No need to apologize, thanks for reverting, I’ll try to repro and figure out what went wrong.
>>
>> —
>> Mehdi
>>
>>
>>
>>>
>>> James
>>>
>>> On Tue, 6 Oct 2015 at 18:21 Mehdi Amini via llvm-commits <llvm-commits at lists.llvm.org
>>> <mailto:llvm-commits at lists.llvm.org>> wrote:
>>>
>>> Author: mehdi_amini
>>> Date: Tue Oct 6 12:19:20 2015
>>> New Revision: 249431
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=249431&view=rev <http://llvm.org/viewvc/llvm-project?rev=249431&view=rev>
>>> Log:
>>> This patch builds on top of D13378 to handle constant condition.
>>>
>>> With this patch, clang -O3 optimizes correctly providing > 1000x speedup on this artificial benchmark):
>>>
>>> for (a=0; a<n; a++)
>>> for (b=0; b<n; b++)
>>> for (c=0; c<n; c++)
>>> for (d=0; d<n; d++)
>>> for (e=0; e<n; e++)
>>> for (f=0; f<n; f++)
>>> x++;
>>> From test-suite/SingleSource/Benchmarks/Shootout/nestedloop.c
>>>
>>> Reviewers: sanjoyd
>>>
>>> Differential Revision: http://reviews.llvm.org/D13390
>>>
>>> From: Mehdi Amini <mehdi.amini at apple.com <mailto:mehdi.amini at apple.com>>
>>>
>>> Added:
>>> llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll
>>> Modified:
>>> llvm/trunk/lib/Analysis/ScalarEvolution.cpp
>>>
>>> Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=249431&r1=249430&r2=249431&view=diff
>>> <http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=249431&r1=249430&r2=249431&view=diff>
>>>
>>> ==============================================================================
>>> --- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
>>> +++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Tue Oct 6 12:19:20 2015
>>> @@ -3904,6 +3904,11 @@ const SCEV *ScalarEvolution::createNodeF
>>> Value *Cond,
>>> Value *TrueVal,
>>> Value *FalseVal) {
>>> + // Handle "constant" branch or select. This can occur for instance when a
>>> + // loop pass transforms an inner loop and moves on to process the outer loop.
>>> + if (auto *CI = dyn_cast<ConstantInt>(Cond))
>>> + return getSCEV(CI->isOne() ? TrueVal : FalseVal);
>>> +
>>> // Try to match some simple smax or umax patterns.
>>> auto *ICI = dyn_cast<ICmpInst>(Cond);
>>> if (!ICI)
>>>
>>> Added: llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll?rev=249431&view=auto
>>> <http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll?rev=249431&view=auto>
>>>
>>> ==============================================================================
>>> --- llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll (added)
>>> +++ llvm/trunk/test/Analysis/ScalarEvolution/constant_condition.ll Tue Oct 6 12:19:20 2015
>>> @@ -0,0 +1,51 @@
>>> +; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
>>> +
>>> +define i32 @branch_true(i32 %x, i32 %y) {
>>> +; CHECK-LABEL: Classifying expressions for: @branch_true
>>> + entry:
>>> + br i1 true, label %add, label %merge
>>> +
>>> + add:
>>> + %sum = add i32 %x, %y
>>> + br label %merge
>>> +
>>> + merge:
>>> + %v = phi i32 [ %sum, %add ], [ %x, %entry ]
>>> +; CHECK: %v = phi i32 [ %sum, %add ], [ %x, %entry ]
>>> +; CHECK-NEXT: --> (%x + %y) U: full-set S: full-set
>>> + ret i32 %v
>>> +}
>>> +
>>> +define i32 @branch_false(i32 %x, i32 %y) {
>>> +; CHECK-LABEL: Classifying expressions for: @branch_false
>>> + entry:
>>> + br i1 false, label %add, label %merge
>>> +
>>> + add:
>>> + %sum = add i32 %x, %y
>>> + br label %merge
>>> +
>>> + merge:
>>> + %v = phi i32 [ %sum, %add ], [ %x, %entry ]
>>> +; CHECK: %v = phi i32 [ %sum, %add ], [ %x, %entry ]
>>> +; CHECK-NEXT: --> %x U: full-set S: full-set
>>> + ret i32 %v
>>> +}
>>> +
>>> +define i32 @select_true(i32 %x, i32 %y) {
>>> +; CHECK-LABEL: Classifying expressions for: @select_true
>>> + entry:
>>> + %v = select i1 true, i32 %x, i32 %y
>>> +; CHECK: %v = select i1 true, i32 %x, i32 %y
>>> +; CHECK-NEXT: --> %x U: full-set S: full-set
>>> + ret i32 %v
>>> +}
>>> +
>>> +define i32 @select_false(i32 %x, i32 %y) {
>>> +; CHECK-LABEL: Classifying expressions for: @select_false
>>> + entry:
>>> + %v = select i1 false, i32 %x, i32 %y
>>> +; CHECK: %v = select i1 false, i32 %x, i32 %y
>>> +; CHECK-NEXT: --> %y U: full-set S: full-set
>>> + ret i32 %v
>>> +}
>>>
>>>
>>> _______________________________________________
>>> llvm-commits mailing list
>>> llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>>
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits