[LLVMdev] about MemoryDependenceAnalysis usage

Daniel Berlin dberlin at dberlin.org
Mon May 11 08:11:03 PDT 2015 

intriguiging.
Is your pass a modulepass, or what?


On Mon, May 11, 2015 at 8:04 AM, Willy WOLFF <willy.mh.wolff at gmail.com> wrote:
> Thanks for your quick answer.
> But it's still the same:
> opt -o /dev/null test.ll -S -load ./libPlaydep.so -O3 -basicaa -playdep
> --debug-pass=Structure
> Pass Arguments:  -targetlibinfo -datalayout -notti -basictti -x86tti -no-aa
> -tbaa -scoped-noalias -assumption-cache-tracker -basicaa -verify-di -ipsccp
> -globalopt -deadargelim -domtree -instcombine -simplifycfg -basiccg
> -prune-eh -inline-cost -inline -functionattrs -argpromotion -sroa -domtree
> -early-cse -lazy-value-info -jump-threading -correlated-propagation
> -simplifycfg -domtree -instcombine -tailcallelim -simplifycfg -reassociate
> -domtree -loops -loop-simplify -lcssa -loop-rotate -licm -loop-unswitch
> -instcombine -scalar-evolution -loop-simplify -lcssa -indvars -loop-idiom
> -loop-deletion -function_tti -loop-unroll -memdep -mldst-motion -domtree
> -memdep -gvn -memdep -memcpyopt -sccp -domtree -instcombine -lazy-value-info
> -jump-threading -correlated-propagation -domtree -memdep -dse -adce
> -simplifycfg -domtree -instcombine -barrier -domtree -loops -loop-simplify
> -lcssa -branch-prob -block-freq -scalar-evolution -loop-vectorize
> -instcombine -scalar-evolution -slp-vectorizer -simplifycfg -domtree
> -instcombine -loops -loop-simplify -lcssa -scalar-evolution -function_tti
> -loop-unroll -alignment-from-assumptions -strip-dead-prototypes -globaldce
> -constmerge -playdep -verify -verify-di -print-module
> Target Library Information
> Data Layout
> No target information
> Target independent code generator's TTI
> X86 Target Transform Info
> No Alias Analysis (always returns 'may' alias)
> Type-Based Alias Analysis
> Scoped NoAlias Alias Analysis
> Assumption Cache Tracker
> Basic Alias Analysis (stateless AA impl)
>   ModulePass Manager
>     Debug Info Verifier
>     Interprocedural Sparse Conditional Constant Propagation
> ....
>      Module Verifier
>     Debug Info Verifier
>     Print module to stderr
> Pass Arguments:  -no-aa -assumption-cache-tracker -targetlibinfo -basicaa
> No Alias Analysis (always returns 'may' alias)
> Assumption Cache Tracker
> Target Library Information
> Basic Alias Analysis (stateless AA impl)
>   ModulePass Manager
>     Unnamed pass: implement Pass::getPassName()
>       Unnamed pass: implement Pass::getPassName()
> Pass Arguments:  -assumption-cache-tracker -no-aa -memdep
> Assumption Cache Tracker
> No Alias Analysis (always returns 'may' alias)
>   FunctionPass Manager
>     Memory Dependence Analysis
> function fct
> for this instruction:   store i32 2, i32* %6, align 4, !tbaa !5
> deps are:
>   %5 = load i32** %4, align 8, !tbaa !1
>   store i32 1, i32* %3, align 4, !tbaa !5
>   %2 = load i32** %1, align 8, !tbaa !1
>
>
> On 11/05/2015 16:50, Daniel Berlin wrote:
>>
>> add -basicaa to your command line :)
>>
>> On Mon, May 11, 2015 at 7:15 AM, Willy WOLFF <willy.mh.wolff at gmail.com>
>> wrote:
>>>
>>> I play a bit more with MemoryDependenceAnalysis by wrapping my pass, and
>>> call explicitely BasicAliasAnalysis. Its still using No Alias Analysis.
>>>
>>> How can I let MemoryDependenceAnalysis use BasicAliasAnalysis?
>>>
>>> Please, find attached my pass.
>>>
>>> I call my pass like this: "opt -o /dev/null -S test.ll -load
>>> libPlaydep.so
>>> -O3 -playdep --debug-pass=Structure"
>>> And the output:
>>>
>>> opt -o /dev/null test.ll -S -load ./libPlaydep.so -O3 -playdep
>>> --debug-pass=Structure
>>> Pass Arguments:  -targetlibinfo -datalayout -notti -basictti -x86tti
>>> -no-aa
>>> -tbaa -scoped-noalias -assumption-cache-tracker -basicaa -verify-di
>>> -ipsccp
>>> -globalopt -deadargelim -domtree -instcombine -simplifycfg -basiccg
>>> -prune-eh -inline-cost -inline -functionattrs -argpromotion -sroa
>>> -domtree
>>> -early-cse -lazy-value-info -jump-threading -correlated-propagation
>>> -simplifycfg -domtree -instcombine -tailcallelim -simplifycfg
>>> -reassociate
>>> -domtree -loops -loop-simplify -lcssa -loop-rotate -licm -loop-unswitch
>>> -instcombine -scalar-evolution -loop-simplify -lcssa -indvars -loop-idiom
>>> -loop-deletion -function_tti -loop-unroll -memdep -mldst-motion -domtree
>>> -memdep -gvn -memdep -memcpyopt -sccp -domtree -instcombine
>>> -lazy-value-info
>>> -jump-threading -correlated-propagation -domtree -memdep -dse -adce
>>> -simplifycfg -domtree -instcombine -barrier -domtree -loops
>>> -loop-simplify
>>> -lcssa -branch-prob -block-freq -scalar-evolution -loop-vectorize
>>> -instcombine -scalar-evolution -slp-vectorizer -simplifycfg -domtree
>>> -instcombine -loops -loop-simplify -lcssa -scalar-evolution -function_tti
>>> -loop-unroll -alignment-from-assumptions -strip-dead-prototypes
>>> -globaldce
>>> -constmerge -playdep -verify -verify-di -print-module
>>> Target Library Information
>>> Data Layout
>>> No target information
>>> Target independent code generator's TTI
>>> X86 Target Transform Info
>>> No Alias Analysis (always returns 'may' alias)
>>> Type-Based Alias Analysis
>>> Scoped NoAlias Alias Analysis
>>> Assumption Cache Tracker
>>> Basic Alias Analysis (stateless AA impl)
>>>    ModulePass Manager
>>>      Debug Info Verifier
>>>      Interprocedural Sparse Conditional Constant Propagation
>>>      Global Variable Optimizer
>>> .....
>>>      FunctionPass Manager
>>>        Module Verifier
>>>      Debug Info Verifier
>>>      Print module to stderr
>>> Pass Arguments:  -no-aa -assumption-cache-tracker -targetlibinfo -basicaa
>>> No Alias Analysis (always returns 'may' alias)
>>> Assumption Cache Tracker
>>> Target Library Information
>>> Basic Alias Analysis (stateless AA impl)
>>>    ModulePass Manager
>>>      Unnamed pass: implement Pass::getPassName()
>>>        Unnamed pass: implement Pass::getPassName()
>>> Pass Arguments:  -assumption-cache-tracker -no-aa -memdep
>>> Assumption Cache Tracker
>>> No Alias Analysis (always returns 'may' alias)
>>>    FunctionPass Manager
>>>      Memory Dependence Analysis
>>> function fct
>>> for this instruction:   store i32 2, i32* %6, align 4, !tbaa !5
>>> deps are:
>>>    %5 = load i32** %4, align 8, !tbaa !1
>>>    store i32 1, i32* %3, align 4, !tbaa !5
>>>    %2 = load i32** %1, align 8, !tbaa !1
>>>
>>>
>>> Cheers,
>>> Willy
>>>
>>>
>>> On 09/05/2015 16:06, Willy WOLFF wrote:
>>>>
>>>>
>>>> Hi,
>>>>
>>>> I try to use MemoryDependenceAnalysis in a pass to analyse a simple
>>>> function:
>>>>
>>>> void fct (int *restrict*restrict M, int *restrict*restrict L) {
>>>> S1:    M[1][1] = 1;
>>>> S2:    L[2][2] = 2;
>>>> }
>>>>
>>>> When I iterate over MemoryDependenceAnalysis on the S2 statement, I get
>>>> the load instruction for the first depth of the array, that’s ok. But I
>>>> get
>>>> also the load and store for the S1 statement.
>>>> I assume the restrict keywoard help the alias analysis to found that
>>>> pointers don’t alias.
>>>> The prototype of this function in llvm-ir is:
>>>> define void @fct(i32** noalias %M, i32** noalias %L) #0 { ….
>>>>
>>>> Did this noalias attribute say that both pointer of i32** didn’t alias?
>>>>
>>>> Also, when I check wich AliasAnalysis pass is called with
>>>> —debug-pass=Structure, I see that Memory Dependence Analysis use No
>>>> Alias
>>>> Analysis, even if I use -O3 before calling my pass. Can we specify which
>>>> AlisAnalysis we want to use inside the pass (in getAnalysisUsage method,
>>>> or
>>>> somewhere else)?
>>>>
>>>> Regards,
>>>> Willy
>>>>
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>
>
> --
> Willy WOLFF
> Etudiant en Master d'informatique à l'Université de Strasbourg
> Ingénierie du Logiciel et des Connaissances, 2em année.
> 06.09.72.81.51 | willy.wolff at etu.unistra.fr

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