Dear LLVM developers,
I am Shen, a PhD student at Lehigh Univ. PA. Now I am implementing a
Program Dependence Graph(PDG) on LLVM. I have 4 passes here:
1. ProgramDependenceGraph (a *ModulePass *on the highest level)
2. DataDependenceGraph (a Intermediate *FunctionPass*).
3. FlowDependenceAnalysis Pass (a intermediate *FunctionPass*) which uses
llvm built-in AliasAnalysis (-basicaa)
4. AliasAnalysis Pass (LLVM built-in Pass)
When my call chain is
DatadependenceGraph <-- FlowDependenceAnalysis <-- AliasAnalysis
everything is fine and basicaa is executed successfully.
My problem is, *when I use a Module Pass to call a Function Pass, the low
level AliasAnalysis does not work anymore*, all return values for location
comparisons are "May Alias". In other words, the call chain
ProgramDependenceGraph(Module Pass) <-- DatadependenceGraph(*Function Pass*)
<-- FlowDependenceAnalysis <-- AliasAnalysis if failed.
However, if *I change ProgramDependenceGraph into a Function Pass, this
call chain works and AliasAnalysis can be executed successfully.*
So, i guess there may be an error in my interaction between Module Pass and
Function Pass. Could you give me some hints to help me solve it? Thank you
very much!
Here are some key code for Pass interaction in my implementation:
bool ProgramDependencyGraph::*runOnModule*(Module &M)
{
...
for(Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
{
DataDependencyGraph &ddgGraph =
getAnalysis<DataDependencyGraph>(*F);
....
}
}
...
void ProgramDependencyGraph::getAnalysisUsage(AnalysisUsage &AU) const
{
...
AU.addRequired<DataDependencyGraph>();
AU.setPreservesAll();
}
Best Regards,
Shen
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Daniel Berlin
2015-Apr-29 20:45 UTC
[LLVMdev] AliasAnalysis calling failed in Pass interaction
On Wed, Apr 29, 2015 at 1:27 PM, Shen Liu <shl413 at lehigh.edu> wrote:> Dear LLVM developers, > > I am Shen, a PhD student at Lehigh Univ. PA. Now I am implementing a > Program Dependence Graph(PDG) on LLVM. I have 4 passes here: > > 1. ProgramDependenceGraph (a ModulePass on the highest level) > 2. DataDependenceGraph (a Intermediate FunctionPass). > 3. FlowDependenceAnalysis Pass (a intermediate FunctionPass) which uses llvm > built-in AliasAnalysis (-basicaa)Does this implement AliasAnalysis?> 4. AliasAnalysis Pass (LLVM built-in Pass) > > When my call chain is > > DatadependenceGraph <-- FlowDependenceAnalysis <-- AliasAnalysis > > everything is fine and basicaa is executed successfully.BasicAA is not AliasAnalysis. BasicAA is *an* AliasAnalysis. If you have not added BasicAliasAnalysis to the pass list, it will not be called when you call AliasAnalysis API.> > My problem is, when I use a Module Pass to call a Function Pass, the low > level AliasAnalysis does not work anymore, all return values for location > comparisons are "May Alias". In other words, the call chain > > ProgramDependenceGraph(Module Pass) <-- DatadependenceGraph(Function Pass) > <-- FlowDependenceAnalysis <-- AliasAnalysis if failed. > > However, if I change ProgramDependenceGraph into a Function Pass, this call > chain works and AliasAnalysis can be executed successfully. > > So, i guess there may be an error in my interaction between Module Pass and > Function Pass. Could you give me some hints to help me solve it? Thank you > very much! > > > Here are some key code for Pass interaction in my implementation: > > bool ProgramDependencyGraph::runOnModule(Module &M) > { > ... > for(Module::iterator F = M.begin(), E = M.end(); F != E; ++F) > { > DataDependencyGraph &ddgGraph = getAnalysis<DataDependencyGraph>(*F); > .... > } > } > > ... > void ProgramDependencyGraph::getAnalysisUsage(AnalysisUsage &AU) const > { > ... > AU.addRequired<DataDependencyGraph>(); > AU.setPreservesAll(); > } >This does not require alias analysis or it's analysis group, which is wrong if you want those to work?> > Best Regards, > > Shen > > > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >
Hi Daniel, thanks for your reply! Yes I didn't implement AA by myself but called builtin -basicaa interface for temporary use. Just add the -basicaa option in my opt command. I hope -basicaa can be called to process to check some simple aliases. And when I do DataDependencyGraph &ddgGraph = getAnalysis<DataDependencyGraph>(*F); inside a Function Pass, it works.What make me confused is when my Pass is a Module Pass, --basicaa cannot be called anymore. It seems the -basicaa option cannot be seen by getAnalysis() if I call it in a Module Pass. Do you have any suggestions? Best Regards, Shen On Wed, Apr 29, 2015 at 4:45 PM, Daniel Berlin <dberlin at dberlin.org> wrote:> On Wed, Apr 29, 2015 at 1:27 PM, Shen Liu <shl413 at lehigh.edu> wrote: > > Dear LLVM developers, > > > > I am Shen, a PhD student at Lehigh Univ. PA. Now I am implementing a > > Program Dependence Graph(PDG) on LLVM. I have 4 passes here: > > > > 1. ProgramDependenceGraph (a ModulePass on the highest level) > > 2. DataDependenceGraph (a Intermediate FunctionPass). > > 3. FlowDependenceAnalysis Pass (a intermediate FunctionPass) which uses > llvm > > built-in AliasAnalysis (-basicaa) > > Does this implement AliasAnalysis? >> > > 4. AliasAnalysis Pass (LLVM built-in Pass) > > > > When my call chain is > > > > DatadependenceGraph <-- FlowDependenceAnalysis <-- AliasAnalysis > > > > everything is fine and basicaa is executed successfully. > > BasicAA is not AliasAnalysis. BasicAA is *an* AliasAnalysis. > > If you have not added BasicAliasAnalysis to the pass list, it will not > be called when you call AliasAnalysis API. > > > > > My problem is, when I use a Module Pass to call a Function Pass, the low > > level AliasAnalysis does not work anymore, all return values for location > > comparisons are "May Alias". In other words, the call chain > > > > ProgramDependenceGraph(Module Pass) <-- DatadependenceGraph(Function > Pass) > > <-- FlowDependenceAnalysis <-- AliasAnalysis if failed. > > > > However, if I change ProgramDependenceGraph into a Function Pass, this > call > > chain works and AliasAnalysis can be executed successfully. > > > > So, i guess there may be an error in my interaction between Module Pass > and > > Function Pass. Could you give me some hints to help me solve it? Thank > you > > very much! > > > > > > Here are some key code for Pass interaction in my implementation: > > > > bool ProgramDependencyGraph::runOnModule(Module &M) > > { > > ... > > for(Module::iterator F = M.begin(), E = M.end(); F != E; ++F) > > { > > DataDependencyGraph &ddgGraph > getAnalysis<DataDependencyGraph>(*F); > > .... > > } > > } > > > > ... > > void ProgramDependencyGraph::getAnalysisUsage(AnalysisUsage &AU) const > > { > > ... > > AU.addRequired<DataDependencyGraph>(); > > AU.setPreservesAll(); > > } > > > > This does not require alias analysis or it's analysis group, which is > wrong if you want those to work? > > > > > Best Regards, > > > > Shen > > > > > > > > _______________________________________________ > > LLVM Developers mailing list > > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev > > >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20150429/51a20527/attachment.html>