[PATCH] MemoryDependenceAnalysis always depends on DominatorTree

[Evan Cheng]

On Mar 29, 2013, at 3:54 PM, Daniel Berlin <dberlin at dberlin.org> wrote:

> On Fri, Mar 29, 2013 at 3:39 PM, Evan Cheng <evan.cheng at apple.com> wrote:
>> 
>> On Mar 27, 2013, at 5:44 PM, Matt Arsenault <Matthew.Arsenault at amd.com> wrote:
>> 
>>> Hi nlewycky,
>>> 
>>> The DominatorTree was optional, but the uses of the tree aren't checked, causing it to crash when not available.
>>> 
>>> I've made DominatorTree required, although I'm not sure if it would be better to put the checks before its uses instead.
>> 
>> Adding the checks before DT is used is probably the better fix. Can you try that? Also, please include a test case.
>> 
> If done, this seems like it would just cause the bug fixed in 166490
> to reoccur, unless that got fixed some other way.  (This is the reason
> the DT checks were added)

It could be fixed by having the DT check return conservatively safe answer when DT is not available. Bill, please comment.

Evan

> 
> The testcase that got added then was: test/Transforms/GVN/crash.ll
> 
>> Evan
>> 
>>> 
>>> http://llvm-reviews.chandlerc.com/D583
>>> 
>>> Files:
>>> lib/Analysis/MemoryDependenceAnalysis.cpp
>>> 
>>> Index: lib/Analysis/MemoryDependenceAnalysis.cpp
>>> ===================================================================
>>> --- lib/Analysis/MemoryDependenceAnalysis.cpp
>>> +++ lib/Analysis/MemoryDependenceAnalysis.cpp
>>> @@ -56,6 +56,7 @@
>>> // Register this pass...
>>> INITIALIZE_PASS_BEGIN(MemoryDependenceAnalysis, "memdep",
>>>                "Memory Dependence Analysis", false, true)
>>> +INITIALIZE_PASS_DEPENDENCY(DominatorTree)
>>> INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
>>> INITIALIZE_PASS_END(MemoryDependenceAnalysis, "memdep",
>>>                      "Memory Dependence Analysis", false, true)
>>> @@ -85,12 +86,13 @@
>>> void MemoryDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
>>>  AU.setPreservesAll();
>>>  AU.addRequiredTransitive<AliasAnalysis>();
>>> +  AU.addRequired<DominatorTree>();
>>> }
>>> 
>>> bool MemoryDependenceAnalysis::runOnFunction(Function &) {
>>>  AA = &getAnalysis<AliasAnalysis>();
>>>  TD = getAnalysisIfAvailable<DataLayout>();
>>> -  DT = getAnalysisIfAvailable<DominatorTree>();
>>> +  DT = &getAnalysis<DominatorTree>();
>>>  if (PredCache == 0)
>>>    PredCache.reset(new PredIteratorCache());
>>>  return false;
>>> <D583.1.patch>_______________________________________________
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>> 
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