[llvm] r272505 - [PM] Port ReversePostOrderFunctionAttrs to the new PM
Sean Silva via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 15 03:22:13 PDT 2016
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
> [ ] 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
>
quick update on the status of this list:
General Scalar:
[x] Simplify the CFG --> this one was already ported and should not have
been included in the original list
[x] Jump Threading
[x] MemCpy Optimization
[x] Promote Memory to Register
[x] MergedLoadStoreMotion
[x] Lazy Value Information Analysis
General IPO:
[x] Dead Argument Elimination
[x] Deduce function attributes in RPO
Loop stuff / vectorization stuff:
[x] Alignment from assumptions
[ ] Canonicalize natural loops --> Should be unblocked for porting.
[ ] Delete dead loops --> Blocked on having loop deletion API in new
loop PM (calls markAsRemoved on LoopInfo)
[ ] Loop Access Analysis --> David is working on this one. In progress at
http://reviews.llvm.org/D20560. "depends on preparation work to hide
strides from the LoopAccessInfo creator interface" which it sounds like
Adam Nemet will get to this week.
[ ] Loop Invariant Code Motion --> Should be unblocked for porting.
[ ] Loop Vectorization --> Blocked on "Loop Access Analysis"
[x] SLP Vectorizer
[ ] Unroll loops --> Blocked on having loop deletion API in new loop PM
(calls markAsRemoved on LoopInfo)
Devirtualization / CFI: --> to avoid merge pain, Peter asked us to hold
off on porting these until his reworking of bitsets is done
[ ] Cross-DSO CFI
[ ] Whole program devirtualization
[ ] Lower bitset metadata
CGSCC passes: --> Exact design of CGSCC is still in the air. Esp. w.r.t.
what happens when mutating the SCC.
[ ] Function Integration/Inlining
[ ] Remove unused exception handling info ---> This one does not mutate
the SCC.
[ ] Promote 'by reference' arguments to scalars
Updated list is as follows:
Loop stuff / vectorization stuff:
[ ] Canonicalize natural loops --> Should be unblocked for porting.
[ ] Loop Invariant Code Motion --> Should be unblocked for porting.
[ ] Loop Access Analysis --> David is working on this one. In
progress at http://reviews.llvm.org/D20560. "depends on preparation work to
hide strides from the LoopAccessInfo creator interface" which it sounds
like Adam Nemet is working on and "should get to it in the next couple of
days".
[ ] Loop Vectorization --> Blocked on "Loop Access Analysis"
Blocked on loop deletion API in new PM: --> Blocked on having loop deletion
API in new loop PM (call markAsRemoved on LoopInfo)
[ ] Delete dead loops
[ ] Unroll loops
Devirtualization / CFI: --> to avoid merge pain, Peter asked us to hold
off on porting these until his reworking of bitsets is done
[ ] Cross-DSO CFI
[ ] Whole program devirtualization
[ ] Lower bitset metadata
CGSCC passes: --> Exact design of CGSCC is still in the air. Esp. w.r.t.
what happens when mutating the SCC.
[ ] Function Integration/Inlining
[ ] Remove unused exception handling info --> This one does not mutate
the SCC.
[ ] Promote 'by reference' arguments to scalars
-- Sean Silva
> 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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