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[Kaleidoscope] Switch to the new PassManager, revisited. (llvm#72324)
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Rollforward of llvm#69032, which was reverted in
[63d19cf](llvm@63d19cf).

New: implemented changes in
llvm#69032 (comment).
Given the PassBuilder is how we expect users to register passes, the
tutorial should reflect that.
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@Logikable @zahiraam
Logikable authored and zahiraam committed Nov 20, 2023
1 parent d24d55e commit 9434824
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80 changes: 54 additions & 26 deletions llvm/docs/tutorial/MyFirstLanguageFrontend/LangImpl04.rst
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Expand Up @@ -94,14 +94,6 @@ use, in the form of "passes".
LLVM Optimization Passes
========================

.. warning::

Due to the transition to the new PassManager infrastructure this tutorial
is based on ``llvm::legacy::FunctionPassManager`` which can be found in
`LegacyPassManager.h <https://llvm.org/doxygen/classllvm_1_1legacy_1_1FunctionPassManager.html>`_.
For the purpose of the this tutorial the above should be used until
the pass manager transition is complete.

LLVM provides many optimization passes, which do many different sorts of
things and have different tradeoffs. Unlike other systems, LLVM doesn't
hold to the mistaken notion that one set of optimizations is right for
Expand All @@ -127,44 +119,80 @@ in. If we wanted to make a "static Kaleidoscope compiler", we would use
exactly the code we have now, except that we would defer running the
optimizer until the entire file has been parsed.

In addition to the distinction between function and module passes, passes can be
divided into transform and analysis passes. Transform passes mutate the IR, and
analysis passes compute information that other passes can use. In order to add
a transform pass, all analysis passes it depends upon must be registered in
advance.

In order to get per-function optimizations going, we need to set up a
`FunctionPassManager <../../WritingAnLLVMPass.html#what-passmanager-doesr>`_ to hold
and organize the LLVM optimizations that we want to run. Once we have
that, we can add a set of optimizations to run. We'll need a new
FunctionPassManager for each module that we want to optimize, so we'll
write a function to create and initialize both the module and pass manager
for us:
add to a function created in the previous chapter (``InitializeModule()``):

.. code-block:: c++

void InitializeModuleAndPassManager(void) {
void InitializeModuleAndManagers(void) {
// Open a new context and module.
TheModule = std::make_unique<Module>("my cool jit", *TheContext);
TheContext = std::make_unique<LLVMContext>();
TheModule = std::make_unique<Module>("KaleidoscopeJIT", *TheContext);
TheModule->setDataLayout(TheJIT->getDataLayout());
// Create a new pass manager attached to it.
TheFPM = std::make_unique<legacy::FunctionPassManager>(TheModule.get());
// Create a new builder for the module.
Builder = std::make_unique<IRBuilder<>>(*TheContext);
// Create new pass and analysis managers.
TheFPM = std::make_unique<FunctionPassManager>();
TheLAM = std::make_unique<LoopAnalysisManager>();
TheFAM = std::make_unique<FunctionAnalysisManager>();
TheCGAM = std::make_unique<CGSCCAnalysisManager>();
TheMAM = std::make_unique<ModuleAnalysisManager>();
ThePIC = std::make_unique<PassInstrumentationCallbacks>();
TheSI = std::make_unique<StandardInstrumentations>(*TheContext,
/*DebugLogging*/ true);
TheSI->registerCallbacks(*ThePIC, TheMAM.get());
...
After initializing the global module ``TheModule`` and the FunctionPassManager,
we need to initialize other parts of the framework. The four AnalysisManagers
allow us to add analysis passes that run across the four levels of the IR
hierarchy. PassInstrumentationCallbacks and StandardInstrumentations are
required for the pass instrumentation framework, which allows developers to
customize what happens between passes.

Once these managers are set up, we use a series of "addPass" calls to add a
bunch of LLVM transform passes:

.. code-block:: c++

// Add transform passes.
// Do simple "peephole" optimizations and bit-twiddling optzns.
TheFPM->add(createInstructionCombiningPass());
TheFPM->addPass(InstCombinePass());
// Reassociate expressions.
TheFPM->add(createReassociatePass());
TheFPM->addPass(ReassociatePass());
// Eliminate Common SubExpressions.
TheFPM->add(createGVNPass());
TheFPM->addPass(GVNPass());
// Simplify the control flow graph (deleting unreachable blocks, etc).
TheFPM->add(createCFGSimplificationPass());

TheFPM->doInitialization();
}

This code initializes the global module ``TheModule``, and the function pass
manager ``TheFPM``, which is attached to ``TheModule``. Once the pass manager is
set up, we use a series of "add" calls to add a bunch of LLVM passes.
TheFPM->addPass(SimplifyCFGPass());

In this case, we choose to add four optimization passes.
The passes we choose here are a pretty standard set
of "cleanup" optimizations that are useful for a wide variety of code. I won't
delve into what they do but, believe me, they are a good starting place :).

Next, we register the analysis passes used by the transform passes.

.. code-block:: c++

// Register analysis passes used in these transform passes.
PassBuilder PB;
PB.registerModuleAnalyses(*TheMAM);
PB.registerFunctionAnalyses(*TheFAM);
PB.crossRegisterProxies(*TheLAM, *TheFAM, *TheCGAM, *TheMAM);
}
Once the PassManager is set up, we need to make use of it. We do this by
running it after our newly created function is constructed (in
``FunctionAST::codegen()``), but before it is returned to the client:
Expand All @@ -179,7 +207,7 @@ running it after our newly created function is constructed (in
verifyFunction(*TheFunction);
// Optimize the function.
TheFPM->run(*TheFunction);
TheFPM->run(*TheFunction, *TheFAM);
return TheFunction;
}
Expand Down
55 changes: 39 additions & 16 deletions llvm/examples/Kaleidoscope/Chapter4/toy.cpp
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Expand Up @@ -7,15 +7,19 @@
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/Passes/StandardInstrumentations.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/InstCombine/InstCombine.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Scalar/GVN.h"
#include "llvm/Transforms/Scalar/Reassociate.h"
#include "llvm/Transforms/Scalar/SimplifyCFG.h"
#include <algorithm>
#include <cassert>
#include <cctype>
Expand Down Expand Up @@ -413,8 +417,14 @@ static std::unique_ptr<LLVMContext> TheContext;
static std::unique_ptr<Module> TheModule;
static std::unique_ptr<IRBuilder<>> Builder;
static std::map<std::string, Value *> NamedValues;
static std::unique_ptr<legacy::FunctionPassManager> TheFPM;
static std::unique_ptr<KaleidoscopeJIT> TheJIT;
static std::unique_ptr<FunctionPassManager> TheFPM;
static std::unique_ptr<LoopAnalysisManager> TheLAM;
static std::unique_ptr<FunctionAnalysisManager> TheFAM;
static std::unique_ptr<CGSCCAnalysisManager> TheCGAM;
static std::unique_ptr<ModuleAnalysisManager> TheMAM;
static std::unique_ptr<PassInstrumentationCallbacks> ThePIC;
static std::unique_ptr<StandardInstrumentations> TheSI;
static std::map<std::string, std::unique_ptr<PrototypeAST>> FunctionProtos;
static ExitOnError ExitOnErr;

Expand Down Expand Up @@ -535,7 +545,7 @@ Function *FunctionAST::codegen() {
verifyFunction(*TheFunction);

// Run the optimizer on the function.
TheFPM->run(*TheFunction);
TheFPM->run(*TheFunction, *TheFAM);

return TheFunction;
}
Expand All @@ -549,28 +559,41 @@ Function *FunctionAST::codegen() {
// Top-Level parsing and JIT Driver
//===----------------------------------------------------------------------===//

static void InitializeModuleAndPassManager() {
static void InitializeModuleAndManagers() {
// Open a new context and module.
TheContext = std::make_unique<LLVMContext>();
TheModule = std::make_unique<Module>("my cool jit", *TheContext);
TheModule = std::make_unique<Module>("KaleidoscopeJIT", *TheContext);
TheModule->setDataLayout(TheJIT->getDataLayout());

// Create a new builder for the module.
Builder = std::make_unique<IRBuilder<>>(*TheContext);

// Create a new pass manager attached to it.
TheFPM = std::make_unique<legacy::FunctionPassManager>(TheModule.get());

// Create new pass and analysis managers.
TheFPM = std::make_unique<FunctionPassManager>();
TheLAM = std::make_unique<LoopAnalysisManager>();
TheFAM = std::make_unique<FunctionAnalysisManager>();
TheCGAM = std::make_unique<CGSCCAnalysisManager>();
TheMAM = std::make_unique<ModuleAnalysisManager>();
ThePIC = std::make_unique<PassInstrumentationCallbacks>();
TheSI = std::make_unique<StandardInstrumentations>(*TheContext,
/*DebugLogging*/ true);
TheSI->registerCallbacks(*ThePIC, TheMAM.get());

// Add transform passes.
// Do simple "peephole" optimizations and bit-twiddling optzns.
TheFPM->add(createInstructionCombiningPass());
TheFPM->addPass(InstCombinePass());
// Reassociate expressions.
TheFPM->add(createReassociatePass());
TheFPM->addPass(ReassociatePass());
// Eliminate Common SubExpressions.
TheFPM->add(createGVNPass());
TheFPM->addPass(GVNPass());
// Simplify the control flow graph (deleting unreachable blocks, etc).
TheFPM->add(createCFGSimplificationPass());
TheFPM->addPass(SimplifyCFGPass());

TheFPM->doInitialization();
// Register analysis passes used in these transform passes.
PassBuilder PB;
PB.registerModuleAnalyses(*TheMAM);
PB.registerFunctionAnalyses(*TheFAM);
PB.crossRegisterProxies(*TheLAM, *TheFAM, *TheCGAM, *TheMAM);
}

static void HandleDefinition() {
Expand All @@ -581,7 +604,7 @@ static void HandleDefinition() {
fprintf(stderr, "\n");
ExitOnErr(TheJIT->addModule(
ThreadSafeModule(std::move(TheModule), std::move(TheContext))));
InitializeModuleAndPassManager();
InitializeModuleAndManagers();
}
} else {
// Skip token for error recovery.
Expand Down Expand Up @@ -613,7 +636,7 @@ static void HandleTopLevelExpression() {

auto TSM = ThreadSafeModule(std::move(TheModule), std::move(TheContext));
ExitOnErr(TheJIT->addModule(std::move(TSM), RT));
InitializeModuleAndPassManager();
InitializeModuleAndManagers();

// Search the JIT for the __anon_expr symbol.
auto ExprSymbol = ExitOnErr(TheJIT->lookup("__anon_expr"));
Expand Down Expand Up @@ -699,7 +722,7 @@ int main() {

TheJIT = ExitOnErr(KaleidoscopeJIT::Create());

InitializeModuleAndPassManager();
InitializeModuleAndManagers();

// Run the main "interpreter loop" now.
MainLoop();
Expand Down
57 changes: 40 additions & 17 deletions llvm/examples/Kaleidoscope/Chapter5/toy.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8,15 +8,19 @@
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PassManager.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/Passes/StandardInstrumentations.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/InstCombine/InstCombine.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Scalar/GVN.h"
#include "llvm/Transforms/Scalar/Reassociate.h"
#include "llvm/Transforms/Scalar/SimplifyCFG.h"
#include <algorithm>
#include <cassert>
#include <cctype>
Expand Down Expand Up @@ -540,8 +544,14 @@ static std::unique_ptr<LLVMContext> TheContext;
static std::unique_ptr<Module> TheModule;
static std::unique_ptr<IRBuilder<>> Builder;
static std::map<std::string, Value *> NamedValues;
static std::unique_ptr<legacy::FunctionPassManager> TheFPM;
static std::unique_ptr<KaleidoscopeJIT> TheJIT;
static std::unique_ptr<FunctionPassManager> TheFPM;
static std::unique_ptr<LoopAnalysisManager> TheLAM;
static std::unique_ptr<FunctionAnalysisManager> TheFAM;
static std::unique_ptr<CGSCCAnalysisManager> TheCGAM;
static std::unique_ptr<ModuleAnalysisManager> TheMAM;
static std::unique_ptr<PassInstrumentationCallbacks> ThePIC;
static std::unique_ptr<StandardInstrumentations> TheSI;
static std::map<std::string, std::unique_ptr<PrototypeAST>> FunctionProtos;
static ExitOnError ExitOnErr;

Expand Down Expand Up @@ -809,7 +819,7 @@ Function *FunctionAST::codegen() {
verifyFunction(*TheFunction);

// Run the optimizer on the function.
TheFPM->run(*TheFunction);
TheFPM->run(*TheFunction, *TheFAM);

return TheFunction;
}
Expand All @@ -823,28 +833,41 @@ Function *FunctionAST::codegen() {
// Top-Level parsing and JIT Driver
//===----------------------------------------------------------------------===//

static void InitializeModuleAndPassManager() {
// Open a new module.
static void InitializeModuleAndManagers() {
// Open a new context and module.
TheContext = std::make_unique<LLVMContext>();
TheModule = std::make_unique<Module>("my cool jit", *TheContext);
TheModule = std::make_unique<Module>("KaleidoscopeJIT", *TheContext);
TheModule->setDataLayout(TheJIT->getDataLayout());

// Create a new builder for the module.
Builder = std::make_unique<IRBuilder<>>(*TheContext);

// Create a new pass manager attached to it.
TheFPM = std::make_unique<legacy::FunctionPassManager>(TheModule.get());

// Create new pass and analysis managers.
TheFPM = std::make_unique<FunctionPassManager>();
TheLAM = std::make_unique<LoopAnalysisManager>();
TheFAM = std::make_unique<FunctionAnalysisManager>();
TheCGAM = std::make_unique<CGSCCAnalysisManager>();
TheMAM = std::make_unique<ModuleAnalysisManager>();
ThePIC = std::make_unique<PassInstrumentationCallbacks>();
TheSI = std::make_unique<StandardInstrumentations>(*TheContext,
/*DebugLogging*/ true);
TheSI->registerCallbacks(*ThePIC, TheMAM.get());

// Add transform passes.
// Do simple "peephole" optimizations and bit-twiddling optzns.
TheFPM->add(createInstructionCombiningPass());
TheFPM->addPass(InstCombinePass());
// Reassociate expressions.
TheFPM->add(createReassociatePass());
TheFPM->addPass(ReassociatePass());
// Eliminate Common SubExpressions.
TheFPM->add(createGVNPass());
TheFPM->addPass(GVNPass());
// Simplify the control flow graph (deleting unreachable blocks, etc).
TheFPM->add(createCFGSimplificationPass());
TheFPM->addPass(SimplifyCFGPass());

TheFPM->doInitialization();
// Register analysis passes used in these transform passes.
PassBuilder PB;
PB.registerModuleAnalyses(*TheMAM);
PB.registerFunctionAnalyses(*TheFAM);
PB.crossRegisterProxies(*TheLAM, *TheFAM, *TheCGAM, *TheMAM);
}

static void HandleDefinition() {
Expand All @@ -855,7 +878,7 @@ static void HandleDefinition() {
fprintf(stderr, "\n");
ExitOnErr(TheJIT->addModule(
ThreadSafeModule(std::move(TheModule), std::move(TheContext))));
InitializeModuleAndPassManager();
InitializeModuleAndManagers();
}
} else {
// Skip token for error recovery.
Expand Down Expand Up @@ -887,7 +910,7 @@ static void HandleTopLevelExpression() {

auto TSM = ThreadSafeModule(std::move(TheModule), std::move(TheContext));
ExitOnErr(TheJIT->addModule(std::move(TSM), RT));
InitializeModuleAndPassManager();
InitializeModuleAndManagers();

// Search the JIT for the __anon_expr symbol.
auto ExprSymbol = ExitOnErr(TheJIT->lookup("__anon_expr"));
Expand Down Expand Up @@ -973,7 +996,7 @@ int main() {

TheJIT = ExitOnErr(KaleidoscopeJIT::Create());

InitializeModuleAndPassManager();
InitializeModuleAndManagers();

// Run the main "interpreter loop" now.
MainLoop();
Expand Down
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