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[LegacyPM] Remove pipeline extension mechanism
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Part of gradually removing the legacy PM optimization pipeline.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D136622
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@aeubanks
aeubanks committed Nov 28, 2022
1 parent 0869a96 commit 7ae6838
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17 changes: 0 additions & 17 deletions llvm/docs/WritingAnLLVMPass.rst
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Expand Up @@ -185,18 +185,6 @@ without modifying it then the third argument is set to ``true``; if a pass is
an analysis pass, for example dominator tree pass, then ``true`` is supplied as
the fourth argument.

If we want to register the pass as a step of an existing pipeline, some extension
points are provided, e.g. ``PassManagerBuilder::EP_EarlyAsPossible`` to apply our
pass before any optimization, or ``PassManagerBuilder::EP_FullLinkTimeOptimizationLast``
to apply it after Link Time Optimizations.

.. code-block:: c++

static llvm::RegisterStandardPasses Y(
llvm::PassManagerBuilder::EP_EarlyAsPossible,
[](const llvm::PassManagerBuilder &Builder,
llvm::legacy::PassManagerBase &PM) { PM.add(new Hello()); });

As a whole, the ``.cpp`` file looks like:

.. code-block:: c++
Expand Down Expand Up @@ -228,11 +216,6 @@ As a whole, the ``.cpp`` file looks like:
false /* Only looks at CFG */,
false /* Analysis Pass */);
static RegisterStandardPasses Y(
PassManagerBuilder::EP_EarlyAsPossible,
[](const PassManagerBuilder &Builder,
legacy::PassManagerBase &PM) { PM.add(new Hello()); });

Now that it's all together, compile the file with a simple "``gmake``" command
from the top level of your build directory and you should get a new file
"``lib/LLVMHello.so``". Note that everything in this file is
Expand Down
104 changes: 0 additions & 104 deletions llvm/include/llvm/Transforms/IPO/PassManagerBuilder.h
View file
Expand Up @@ -63,68 +63,6 @@ class PassManagerBuilder {
ExtensionFn;
typedef int GlobalExtensionID;

enum ExtensionPointTy {
/// EP_EarlyAsPossible - This extension point allows adding passes before
/// any other transformations, allowing them to see the code as it is coming
/// out of the frontend.
EP_EarlyAsPossible,

/// EP_ModuleOptimizerEarly - This extension point allows adding passes
/// just before the main module-level optimization passes.
EP_ModuleOptimizerEarly,

/// EP_LoopOptimizerEnd - This extension point allows adding loop passes to
/// the end of the loop optimizer.
EP_LoopOptimizerEnd,

/// EP_ScalarOptimizerLate - This extension point allows adding optimization
/// passes after most of the main optimizations, but before the last
/// cleanup-ish optimizations.
EP_ScalarOptimizerLate,

/// EP_OptimizerLast -- This extension point allows adding passes that
/// run after everything else.
EP_OptimizerLast,

/// EP_VectorizerStart - This extension point allows adding optimization
/// passes before the vectorizer and other highly target specific
/// optimization passes are executed.
EP_VectorizerStart,

/// EP_EnabledOnOptLevel0 - This extension point allows adding passes that
/// should not be disabled by O0 optimization level. The passes will be
/// inserted after the inlining pass.
EP_EnabledOnOptLevel0,

/// EP_Peephole - This extension point allows adding passes that perform
/// peephole optimizations similar to the instruction combiner. These passes
/// will be inserted after each instance of the instruction combiner pass.
EP_Peephole,

/// EP_LateLoopOptimizations - This extension point allows adding late loop
/// canonicalization and simplification passes. This is the last point in
/// the loop optimization pipeline before loop deletion. Each pass added
/// here must be an instance of LoopPass.
/// This is the place to add passes that can remove loops, such as target-
/// specific loop idiom recognition.
EP_LateLoopOptimizations,

/// EP_CGSCCOptimizerLate - This extension point allows adding CallGraphSCC
/// passes at the end of the main CallGraphSCC passes and before any
/// function simplification passes run by CGPassManager.
EP_CGSCCOptimizerLate,

/// EP_FullLinkTimeOptimizationEarly - This extensions point allow adding
/// passes that
/// run at Link Time, before Full Link Time Optimization.
EP_FullLinkTimeOptimizationEarly,

/// EP_FullLinkTimeOptimizationLast - This extensions point allow adding
/// passes that
/// run at Link Time, after Full Link Time Optimization.
EP_FullLinkTimeOptimizationLast,
};

/// The Optimization Level - Specify the basic optimization level.
/// 0 = -O0, 1 = -O1, 2 = -O2, 3 = -O3
unsigned OptLevel;
Expand Down Expand Up @@ -166,32 +104,11 @@ class PassManagerBuilder {
unsigned LicmMssaOptCap;
unsigned LicmMssaNoAccForPromotionCap;

private:
/// ExtensionList - This is list of all of the extensions that are registered.
std::vector<std::pair<ExtensionPointTy, ExtensionFn>> Extensions;

public:
PassManagerBuilder();
~PassManagerBuilder();
/// Adds an extension that will be used by all PassManagerBuilder instances.
/// This is intended to be used by plugins, to register a set of
/// optimisations to run automatically.
///
/// \returns A global extension identifier that can be used to remove the
/// extension.
static GlobalExtensionID addGlobalExtension(ExtensionPointTy Ty,
ExtensionFn Fn);
/// Removes an extension that was previously added using addGlobalExtension.
/// This is also intended to be used by plugins, to remove any extension that
/// was previously registered before being unloaded.
///
/// \param ExtensionID Identifier of the extension to be removed.
static void removeGlobalExtension(GlobalExtensionID ExtensionID);
void addExtension(ExtensionPointTy Ty, ExtensionFn Fn);

private:
void addExtensionsToPM(ExtensionPointTy ETy,
legacy::PassManagerBase &PM) const;
void addInitialAliasAnalysisPasses(legacy::PassManagerBase &PM) const;
void addFunctionSimplificationPasses(legacy::PassManagerBase &MPM);
void addVectorPasses(legacy::PassManagerBase &PM, bool IsFullLTO);
Expand All @@ -206,27 +123,6 @@ class PassManagerBuilder {
void populateModulePassManager(legacy::PassManagerBase &MPM);
};

/// Registers a function for adding a standard set of passes. This should be
/// used by optimizer plugins to allow all front ends to transparently use
/// them. Create a static instance of this class in your plugin, providing a
/// private function that the PassManagerBuilder can use to add your passes.
class RegisterStandardPasses {
PassManagerBuilder::GlobalExtensionID ExtensionID;

public:
RegisterStandardPasses(PassManagerBuilder::ExtensionPointTy Ty,
PassManagerBuilder::ExtensionFn Fn) {
ExtensionID = PassManagerBuilder::addGlobalExtension(Ty, std::move(Fn));
}

~RegisterStandardPasses() {
// If the collection holding the global extensions is destroyed after the
// plugin is unloaded, the extension has to be removed here. Indeed, the
// destructor of the ExtensionFn may reference code in the plugin.
PassManagerBuilder::removeGlobalExtension(ExtensionID);
}
};

inline PassManagerBuilder *unwrap(LLVMPassManagerBuilderRef P) {
return reinterpret_cast<PassManagerBuilder*>(P);
}
Expand Down
80 changes: 0 additions & 80 deletions llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
View file
Expand Up @@ -68,64 +68,6 @@ PassManagerBuilder::~PassManagerBuilder() {
delete Inliner;
}

/// Set of global extensions, automatically added as part of the standard set.
static ManagedStatic<
SmallVector<std::tuple<PassManagerBuilder::ExtensionPointTy,
PassManagerBuilder::ExtensionFn,
PassManagerBuilder::GlobalExtensionID>,
8>>
GlobalExtensions;
static PassManagerBuilder::GlobalExtensionID GlobalExtensionsCounter;

/// Check if GlobalExtensions is constructed and not empty.
/// Since GlobalExtensions is a managed static, calling 'empty()' will trigger
/// the construction of the object.
static bool GlobalExtensionsNotEmpty() {
return GlobalExtensions.isConstructed() && !GlobalExtensions->empty();
}

PassManagerBuilder::GlobalExtensionID
PassManagerBuilder::addGlobalExtension(PassManagerBuilder::ExtensionPointTy Ty,
PassManagerBuilder::ExtensionFn Fn) {
auto ExtensionID = GlobalExtensionsCounter++;
GlobalExtensions->push_back(std::make_tuple(Ty, std::move(Fn), ExtensionID));
return ExtensionID;
}

void PassManagerBuilder::removeGlobalExtension(
PassManagerBuilder::GlobalExtensionID ExtensionID) {
// RegisterStandardPasses may try to call this function after GlobalExtensions
// has already been destroyed; doing so should not generate an error.
if (!GlobalExtensions.isConstructed())
return;

auto GlobalExtension =
llvm::find_if(*GlobalExtensions, [ExtensionID](const auto &elem) {
return std::get<2>(elem) == ExtensionID;
});
assert(GlobalExtension != GlobalExtensions->end() &&
"The extension ID to be removed should always be valid.");

GlobalExtensions->erase(GlobalExtension);
}

void PassManagerBuilder::addExtension(ExtensionPointTy Ty, ExtensionFn Fn) {
Extensions.push_back(std::make_pair(Ty, std::move(Fn)));
}

void PassManagerBuilder::addExtensionsToPM(ExtensionPointTy ETy,
legacy::PassManagerBase &PM) const {
if (GlobalExtensionsNotEmpty()) {
for (auto &Ext : *GlobalExtensions) {
if (std::get<0>(Ext) == ETy)
std::get<1>(Ext)(*this, PM);
}
}
for (const auto &[PT, Fn] : Extensions)
if (PT == ETy)
Fn(*this, PM);
}

void PassManagerBuilder::addInitialAliasAnalysisPasses(
legacy::PassManagerBase &PM) const {
// Add TypeBasedAliasAnalysis before BasicAliasAnalysis so that
Expand All @@ -137,8 +79,6 @@ void PassManagerBuilder::addInitialAliasAnalysisPasses(

void PassManagerBuilder::populateFunctionPassManager(
legacy::FunctionPassManager &FPM) {
addExtensionsToPM(EP_EarlyAsPossible, FPM);

// Add LibraryInfo if we have some.
if (LibraryInfo)
FPM.add(new TargetLibraryInfoWrapperPass(*LibraryInfo));
Expand Down Expand Up @@ -177,7 +117,6 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
MPM.add(createInstructionCombiningPass());
if (SizeLevel == 0)
MPM.add(createLibCallsShrinkWrapPass());
addExtensionsToPM(EP_Peephole, MPM);

// TODO: Investigate the cost/benefit of tail call elimination on debugging.
if (OptLevel > 1)
Expand Down Expand Up @@ -218,13 +157,11 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
// We resume loop passes creating a second loop pipeline here.
MPM.add(createLoopIdiomPass()); // Recognize idioms like memset.
MPM.add(createIndVarSimplifyPass()); // Canonicalize indvars
addExtensionsToPM(EP_LateLoopOptimizations, MPM);
MPM.add(createLoopDeletionPass()); // Delete dead loops

// Unroll small loops and perform peeling.
MPM.add(createSimpleLoopUnrollPass(OptLevel, DisableUnrollLoops,
ForgetAllSCEVInLoopUnroll));
addExtensionsToPM(EP_LoopOptimizerEnd, MPM);
// This ends the loop pass pipelines.

// Break up allocas that may now be splittable after loop unrolling.
Expand All @@ -244,7 +181,6 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
// Run instcombine after redundancy elimination to exploit opportunities
// opened up by them.
MPM.add(createInstructionCombiningPass());
addExtensionsToPM(EP_Peephole, MPM);
if (OptLevel > 1) {
MPM.add(createJumpThreadingPass()); // Thread jumps
MPM.add(createCorrelatedValuePropagationPass());
Expand All @@ -259,14 +195,11 @@ void PassManagerBuilder::addFunctionSimplificationPasses(
/*AllowSpeculation=*/true));
}

addExtensionsToPM(EP_ScalarOptimizerLate, MPM);

// Merge & remove BBs and sink & hoist common instructions.
MPM.add(createCFGSimplificationPass(
SimplifyCFGOptions().hoistCommonInsts(true).sinkCommonInsts(true)));
// Clean up after everything.
MPM.add(createInstructionCombiningPass());
addExtensionsToPM(EP_Peephole, MPM);
}

/// FIXME: Should LTO cause any differences to this set of passes?
Expand Down Expand Up @@ -327,7 +260,6 @@ void PassManagerBuilder::addVectorPasses(legacy::PassManagerBase &PM,
PM.add(createVectorCombinePass());

if (!IsFullLTO) {
addExtensionsToPM(EP_Peephole, PM);
PM.add(createInstructionCombiningPass());

// Unroll small loops
Expand Down Expand Up @@ -379,10 +311,6 @@ void PassManagerBuilder::populateModulePassManager(
// builds. The function merging pass is
if (MergeFunctions)
MPM.add(createMergeFunctionsPass());
else if (GlobalExtensionsNotEmpty() || !Extensions.empty())
MPM.add(createBarrierNoopPass());

addExtensionsToPM(EP_EnabledOnOptLevel0, MPM);

MPM.add(createAnnotationRemarksLegacyPass());
return;
Expand All @@ -397,8 +325,6 @@ void PassManagerBuilder::populateModulePassManager(
// Infer attributes about declarations if possible.
MPM.add(createInferFunctionAttrsLegacyPass());

addExtensionsToPM(EP_ModuleOptimizerEarly, MPM);

if (OptLevel > 2)
MPM.add(createCallSiteSplittingPass());

Expand All @@ -412,7 +338,6 @@ void PassManagerBuilder::populateModulePassManager(
MPM.add(createDeadArgEliminationPass()); // Dead argument elimination

MPM.add(createInstructionCombiningPass()); // Clean up after IPCP & DAE
addExtensionsToPM(EP_Peephole, MPM);
MPM.add(
createCFGSimplificationPass(SimplifyCFGOptions().convertSwitchRangeToICmp(
true))); // Clean up after IPCP & DAE
Expand All @@ -437,7 +362,6 @@ void PassManagerBuilder::populateModulePassManager(

MPM.add(createPostOrderFunctionAttrsLegacyPass());

addExtensionsToPM(EP_CGSCCOptimizerLate, MPM);
addFunctionSimplificationPasses(MPM);

// FIXME: This is a HACK! The inliner pass above implicitly creates a CGSCC
Expand Down Expand Up @@ -490,8 +414,6 @@ void PassManagerBuilder::populateModulePassManager(
MPM.add(createFloat2IntPass());
MPM.add(createLowerConstantIntrinsicsPass());

addExtensionsToPM(EP_VectorizerStart, MPM);

// Re-rotate loops in all our loop nests. These may have fallout out of
// rotated form due to GVN or other transformations, and the vectorizer relies
// on the rotated form. Disable header duplication at -Oz.
Expand Down Expand Up @@ -536,8 +458,6 @@ void PassManagerBuilder::populateModulePassManager(
MPM.add(createCFGSimplificationPass(
SimplifyCFGOptions().convertSwitchRangeToICmp(true)));

addExtensionsToPM(EP_OptimizerLast, MPM);

MPM.add(createAnnotationRemarksLegacyPass());
}

Expand Down

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