[llvm] r272505 - [PM] Port ReversePostOrderFunctionAttrs to the new PM

Sean Silva via llvm-commits llvm-commits at lists.llvm.org
Sun Jun 12 07:21:51 PDT 2016


To avoid collisions, I have LVI and JumpThreading ported. Will commit them
when I have a moment to watch the bots.

On Sun, Jun 12, 2016 at 2:28 AM, Sean Silva <chisophugis at gmail.com> wrote:

>
>
> On Sun, Jun 12, 2016 at 12:48 AM, Sean Silva via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: silvas
>> Date: Sun Jun 12 02:48:51 2016
>> New Revision: 272505
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=272505&view=rev
>> Log:
>> [PM] Port ReversePostOrderFunctionAttrs to the new PM
>>
>> Below are my super rough notes when porting. They can probably serve as
>> a basic guide for porting other passes to the new PM. As I port more
>> passes I'll expand and generalize this and make a proper
>> docs/HowToPortToNewPassManager.rst document. There is also missing
>> documentation for general concepts and API's in the new PM which will
>> require some documentation.
>> Once there is proper documentation in place we can put up a list of
>> passes that have to be ported and game-ify/crowdsource the rest of the
>> porting (at least of the middle end; the backend is still unclear).
>>
>> I will however be taking personal responsibility for ensuring that the
>> LLD/ELF LTO pipeline is ported in a timely fashion. The remaining passes
>> to be ported are (do something like
>> `git grep "<the string in the bullet point below>"` to find the pass):
>>
>> General Scalar:
>> [ ] Simplify the CFG
>>
>
> Just noticed the simplifycfg is already ported. So scratch that one off
> the list.
>
> -- Sean Silva
>
>
>> [ ] Jump Threading
>> [ ] MemCpy Optimization
>> [ ] Promote Memory to Register
>> [ ] MergedLoadStoreMotion
>> [ ] Lazy Value Information Analysis
>>
>> General IPO:
>> [ ] Dead Argument Elimination
>> [ ] Deduce function attributes in RPO
>>
>> Loop stuff / vectorization stuff:
>> [ ] Alignment from assumptions
>> [ ] Canonicalize natural loops
>> [ ] Delete dead loops
>> [ ] Loop Access Analysis
>> [ ] Loop Invariant Code Motion
>> [ ] Loop Vectorization
>> [ ] SLP Vectorizer
>> [ ] Unroll loops
>>
>> Devirtualization / CFI:
>> [ ] Cross-DSO CFI
>> [ ] Whole program devirtualization
>> [ ] Lower bitset metadata
>>
>> CGSCC passes:
>> [ ] Function Integration/Inlining
>> [ ] Remove unused exception handling info
>> [ ] Promote 'by reference' arguments to scalars
>>
>> Please let me know if you are interested in working on any of the passes
>> in the above list (e.g. reply to the post-commit thread for this patch).
>> I'll probably be tackling "General Scalar" and "General IPO" first FWIW.
>>
>> Steps as I port "Deduce function attributes in RPO"
>> ---------------------------------------------------
>>
>> (note: if you are doing any work based on these notes, please leave a
>> note in the post-commit review thread for this commit with any
>> improvements / suggestions / incompleteness you ran into!)
>>
>> Note: "Deduce function attributes in RPO" is a module pass.
>>
>> 1. Do preparatory refactoring.
>>
>> Do preparatory factoring. In this case all I had to do was to pull out a
>> static helper (r272503).
>> (TODO: give more advice here e.g. if pass holds state or something)
>>
>> 2. Rename the old pass class.
>>
>> llvm/lib/Transforms/IPO/FunctionAttrs.cpp
>> Rename class ReversePostOrderFunctionAttrs ->
>> ReversePostOrderFunctionAttrsLegacyPass
>> in preparation for adding a class ReversePostOrderFunctionAttrs as the
>> pass in the new PM.
>> (edit: actually wait what? The new class name will be
>> ReversePostOrderFunctionAttrsPass, so it doesn't conflict. So this step is
>> sort of useless churn).
>>
>> llvm/include/llvm/InitializePasses.h
>> llvm/lib/LTO/LTOCodeGenerator.cpp
>> llvm/lib/Transforms/IPO/IPO.cpp
>> llvm/lib/Transforms/IPO/FunctionAttrs.cpp
>> Rename initializeReversePostOrderFunctionAttrsPass ->
>> initializeReversePostOrderFunctionAttrsLegacyPassPass
>> (note that the "PassPass" thing falls out of
>> `s/ReversePostOrderFunctionAttrs/ReversePostOrderFunctionAttrsLegacyPass/`)
>> Note that the INITIALIZE_PASS macro is what creates this identifier name,
>> so renaming the class requires this renaming too.
>>
>> Note that createReversePostOrderFunctionAttrsPass does not need to be
>> renamed since its name is not generated from the class name.
>>
>> 3. Add the new PM pass class.
>>
>> In the new PM all passes need to have their
>> declaration in a header somewhere, so you will often need to add a header.
>> In this case
>> llvm/include/llvm/Transforms/IPO/FunctionAttrs.h is already there because
>> PostOrderFunctionAttrsPass was already ported.
>> The file-level comment from the .cpp file can be used as the file-level
>> comment for the new header. You may want to tweak the wording slightly
>> from "this file implements" to "this file provides" or similar.
>>
>> Add declaration for the new PM pass in this header:
>>
>>     class ReversePostOrderFunctionAttrsPass
>>         : public PassInfoMixin<ReversePostOrderFunctionAttrsPass> {
>>     public:
>>       PreservedAnalyses run(Module &M, AnalysisManager<Module> &AM);
>>     };
>>
>> Its name should end with `Pass` for consistency (note that this doesn't
>> collide with the names of most old PM passes). E.g. call it
>> `<name of the old PM pass>Pass`.
>>
>> Also, move the doxygen comment from the old PM pass to the declaration of
>> this class in the header.
>> Also, include the declaration for the new PM class
>> `llvm/Transforms/IPO/FunctionAttrs.h` at the top of the file (in this
>> case,
>> it was already done when the other pass in this file was ported).
>>
>> Now define the `run` method for the new class.
>> The main things here are:
>> a) Use AM.getResult<...>(M) to get results instead of `getAnalysis<...>()`
>>
>> b) If the old PM pass would have returned "false" (i.e. `Changed ==
>> false`), then you should return PreservedAnalyses::all();
>>
>> c) In the old PM getAnalysisUsage method, observe the calls
>>    `AU.addPreserved<...>();`.
>>
>>    In the case `Changed == true`, for each preserved analysis you should
>> do
>>    call `PA.preserve<...>()` on a PreservedAnalyses object and return it.
>>    E.g.:
>>
>>        PreservedAnalyses PA;
>>        PA.preserve<CallGraphAnalysis>();
>>        return PA;
>>
>> Note that calls to skipModule/skipFunction are not supported in the new PM
>> currently, so optnone and optimization bisect support do not work. You can
>> just drop those calls for now.
>>
>> 4. Add the pass to the new PM pass registry to make it available in opt.
>>
>> In llvm/lib/Passes/PassBuilder.cpp add a #include for your header.
>> `#include "llvm/Transforms/IPO/FunctionAttrs.h"`
>> In this case there is already an include (from when
>> PostOrderFunctionAttrsPass was ported).
>>
>> Add your pass to llvm/lib/Passes/PassRegistry.def
>> In this case, I added
>> `MODULE_PASS("rpo-functionattrs", ReversePostOrderFunctionAttrsPass())`
>> The string is from the `INITIALIZE_PASS*` macros used in the old pass
>> manager.
>>
>> Then choose a test that uses the pass and use the new PM `-passes=...` to
>> run it.
>> E.g. in this case there is a test that does:
>> ; RUN: opt < %s -basicaa -functionattrs -rpo-functionattrs -S | FileCheck
>> %s
>> I have added the line:
>> ; RUN: opt < %s -aa-pipeline=basic-aa
>> -passes='require<targetlibinfo>,cgscc(function-attrs),rpo-functionattrs' -S
>> | FileCheck %s
>> The `-aa-pipeline=basic-aa` and
>> `require<targetlibinfo>,cgscc(function-attrs)` are what is needed to run
>> functionattrs in the new PM (note that in the new PM "functionattrs"
>> becomes "function-attrs" for some reason). This is just pulled from
>> `readattrs.ll` which contains the change from when functionattrs was
>> ported
>> to the new PM.
>> Adding rpo-functionattrs causes the pass that was just ported to run.
>>
>> Modified:
>>     llvm/trunk/include/llvm/InitializePasses.h
>>     llvm/trunk/include/llvm/Transforms/IPO/FunctionAttrs.h
>>     llvm/trunk/lib/LTO/LTOCodeGenerator.cpp
>>     llvm/trunk/lib/Passes/PassRegistry.def
>>     llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp
>>     llvm/trunk/lib/Transforms/IPO/IPO.cpp
>>     llvm/trunk/test/Transforms/FunctionAttrs/norecurse.ll
>>
>> Modified: llvm/trunk/include/llvm/InitializePasses.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/InitializePasses.h?rev=272505&r1=272504&r2=272505&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/include/llvm/InitializePasses.h (original)
>> +++ llvm/trunk/include/llvm/InitializePasses.h Sun Jun 12 02:48:51 2016
>> @@ -279,7 +279,7 @@ void initializeRegionPrinterPass(PassReg
>>  void initializeRegionViewerPass(PassRegistry&);
>>  void initializeRegisterCoalescerPass(PassRegistry&);
>>  void initializeRenameIndependentSubregsPass(PassRegistry&);
>> -void initializeReversePostOrderFunctionAttrsPass(PassRegistry&);
>> +void
>> initializeReversePostOrderFunctionAttrsLegacyPassPass(PassRegistry&);
>>  void initializeRewriteStatepointsForGCPass(PassRegistry&);
>>  void initializeRewriteSymbolsPass(PassRegistry&);
>>  void initializeSCCPLegacyPassPass(PassRegistry &);
>>
>> Modified: llvm/trunk/include/llvm/Transforms/IPO/FunctionAttrs.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/IPO/FunctionAttrs.h?rev=272505&r1=272504&r2=272505&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/include/llvm/Transforms/IPO/FunctionAttrs.h (original)
>> +++ llvm/trunk/include/llvm/Transforms/IPO/FunctionAttrs.h Sun Jun 12
>> 02:48:51 2016
>> @@ -37,6 +37,21 @@ struct PostOrderFunctionAttrsPass : Pass
>>  /// in post-order.
>>  Pass *createPostOrderFunctionAttrsLegacyPass();
>>
>> +/// A pass to do RPO deduction and propagation of function attributes.
>> +///
>> +/// This pass provides a general RPO or "top down" propagation of
>> +/// function attributes. For a few (rare) cases, we can deduce
>> significantly
>> +/// more about function attributes by working in RPO, so this pass
>> +/// provides the compliment to the post-order pass above where the
>> majority of
>> +/// deduction is performed.
>> +// FIXME: Currently there is no RPO CGSCC pass structure to slide into
>> and so
>> +// this is a boring module pass, but eventually it should be an RPO
>> CGSCC pass
>> +// when such infrastructure is available.
>> +class ReversePostOrderFunctionAttrsPass
>> +    : public PassInfoMixin<ReversePostOrderFunctionAttrsPass> {
>> +public:
>> +  PreservedAnalyses run(Module &M, AnalysisManager<Module> &AM);
>> +};
>>  }
>>
>>  #endif // LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
>>
>> Modified: llvm/trunk/lib/LTO/LTOCodeGenerator.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/LTO/LTOCodeGenerator.cpp?rev=272505&r1=272504&r2=272505&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/LTO/LTOCodeGenerator.cpp (original)
>> +++ llvm/trunk/lib/LTO/LTOCodeGenerator.cpp Sun Jun 12 02:48:51 2016
>> @@ -122,7 +122,7 @@ void LTOCodeGenerator::initializeLTOPass
>>    initializeSROA_DTPass(R);
>>    initializeSROA_SSAUpPass(R);
>>    initializePostOrderFunctionAttrsLegacyPassPass(R);
>> -  initializeReversePostOrderFunctionAttrsPass(R);
>> +  initializeReversePostOrderFunctionAttrsLegacyPassPass(R);
>>    initializeGlobalsAAWrapperPassPass(R);
>>    initializeLICMPass(R);
>>    initializeMergedLoadStoreMotionPass(R);
>>
>> Modified: llvm/trunk/lib/Passes/PassRegistry.def
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Passes/PassRegistry.def?rev=272505&r1=272504&r2=272505&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Passes/PassRegistry.def (original)
>> +++ llvm/trunk/lib/Passes/PassRegistry.def Sun Jun 12 02:48:51 2016
>> @@ -56,6 +56,7 @@ MODULE_PASS("print-profile-summary", Pro
>>  MODULE_PASS("print-callgraph", CallGraphPrinterPass(dbgs()))
>>  MODULE_PASS("print", PrintModulePass(dbgs()))
>>  MODULE_PASS("print-lcg", LazyCallGraphPrinterPass(dbgs()))
>> +MODULE_PASS("rpo-functionattrs", ReversePostOrderFunctionAttrsPass())
>>  MODULE_PASS("sample-profile", SampleProfileLoaderPass())
>>  MODULE_PASS("strip-dead-prototypes", StripDeadPrototypesPass())
>>  MODULE_PASS("verify", VerifierPass())
>>
>> Modified: llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp?rev=272505&r1=272504&r2=272505&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp (original)
>> +++ llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp Sun Jun 12 02:48:51
>> 2016
>> @@ -1137,20 +1137,10 @@ bool PostOrderFunctionAttrsLegacyPass::r
>>  }
>>
>>  namespace {
>> -/// A pass to do RPO deduction and propagation of function attributes.
>> -///
>> -/// This pass provides a general RPO or "top down" propagation of
>> -/// function attributes. For a few (rare) cases, we can deduce
>> significantly
>> -/// more about function attributes by working in RPO, so this pass
>> -/// provides the compliment to the post-order pass above where the
>> majority of
>> -/// deduction is performed.
>> -// FIXME: Currently there is no RPO CGSCC pass structure to slide into
>> and so
>> -// this is a boring module pass, but eventually it should be an RPO
>> CGSCC pass
>> -// when such infrastructure is available.
>> -struct ReversePostOrderFunctionAttrs : public ModulePass {
>> +struct ReversePostOrderFunctionAttrsLegacyPass : public ModulePass {
>>    static char ID; // Pass identification, replacement for typeid
>> -  ReversePostOrderFunctionAttrs() : ModulePass(ID) {
>> -
>> initializeReversePostOrderFunctionAttrsPass(*PassRegistry::getPassRegistry());
>> +  ReversePostOrderFunctionAttrsLegacyPass() : ModulePass(ID) {
>> +
>> initializeReversePostOrderFunctionAttrsLegacyPassPass(*PassRegistry::getPassRegistry());
>>    }
>>
>>    bool runOnModule(Module &M) override;
>> @@ -1163,15 +1153,15 @@ struct ReversePostOrderFunctionAttrs : p
>>  };
>>  }
>>
>> -char ReversePostOrderFunctionAttrs::ID = 0;
>> -INITIALIZE_PASS_BEGIN(ReversePostOrderFunctionAttrs, "rpo-functionattrs",
>> +char ReversePostOrderFunctionAttrsLegacyPass::ID = 0;
>> +INITIALIZE_PASS_BEGIN(ReversePostOrderFunctionAttrsLegacyPass,
>> "rpo-functionattrs",
>>                        "Deduce function attributes in RPO", false, false)
>>  INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
>> -INITIALIZE_PASS_END(ReversePostOrderFunctionAttrs, "rpo-functionattrs",
>> +INITIALIZE_PASS_END(ReversePostOrderFunctionAttrsLegacyPass,
>> "rpo-functionattrs",
>>                      "Deduce function attributes in RPO", false, false)
>>
>>  Pass *llvm::createReversePostOrderFunctionAttrsPass() {
>> -  return new ReversePostOrderFunctionAttrs();
>> +  return new ReversePostOrderFunctionAttrsLegacyPass();
>>  }
>>
>>  static bool addNoRecurseAttrsTopDown(Function &F) {
>> @@ -1229,7 +1219,7 @@ static bool deduceFunctionAttributeInRPO
>>    return Changed;
>>  }
>>
>> -bool ReversePostOrderFunctionAttrs::runOnModule(Module &M) {
>> +bool ReversePostOrderFunctionAttrsLegacyPass::runOnModule(Module &M) {
>>    if (skipModule(M))
>>      return false;
>>
>> @@ -1237,3 +1227,15 @@ bool ReversePostOrderFunctionAttrs::runO
>>
>>    return deduceFunctionAttributeInRPO(M, CG);
>>  }
>> +
>> +PreservedAnalyses
>> +ReversePostOrderFunctionAttrsPass::run(Module &M,
>> AnalysisManager<Module> &AM) {
>> +  auto &CG = AM.getResult<CallGraphAnalysis>(M);
>> +
>> +  bool Changed = deduceFunctionAttributeInRPO(M, CG);
>> +  if (!Changed)
>> +    return PreservedAnalyses::all();
>> +  PreservedAnalyses PA;
>> +  PA.preserve<CallGraphAnalysis>();
>> +  return PA;
>> +}
>>
>> Modified: llvm/trunk/lib/Transforms/IPO/IPO.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/IPO.cpp?rev=272505&r1=272504&r2=272505&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/IPO/IPO.cpp (original)
>> +++ llvm/trunk/lib/Transforms/IPO/IPO.cpp Sun Jun 12 02:48:51 2016
>> @@ -43,7 +43,7 @@ void llvm::initializeIPO(PassRegistry &R
>>    initializeMergeFunctionsPass(Registry);
>>    initializePartialInlinerPass(Registry);
>>    initializePostOrderFunctionAttrsLegacyPassPass(Registry);
>> -  initializeReversePostOrderFunctionAttrsPass(Registry);
>> +  initializeReversePostOrderFunctionAttrsLegacyPassPass(Registry);
>>    initializePruneEHPass(Registry);
>>    initializeStripDeadPrototypesLegacyPassPass(Registry);
>>    initializeStripSymbolsPass(Registry);
>>
>> Modified: llvm/trunk/test/Transforms/FunctionAttrs/norecurse.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/norecurse.ll?rev=272505&r1=272504&r2=272505&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/FunctionAttrs/norecurse.ll (original)
>> +++ llvm/trunk/test/Transforms/FunctionAttrs/norecurse.ll Sun Jun 12
>> 02:48:51 2016
>> @@ -1,4 +1,5 @@
>>  ; RUN: opt < %s -basicaa -functionattrs -rpo-functionattrs -S |
>> FileCheck %s
>> +; RUN: opt < %s -aa-pipeline=basic-aa
>> -passes='require<targetlibinfo>,cgscc(function-attrs),rpo-functionattrs' -S
>> | FileCheck %s
>>
>>  ; CHECK: define i32 @leaf() #0
>>  define i32 @leaf() {
>>
>>
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>
>
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