7c3c981442
DFAJumpThreading JumpThreading LibCallsShrink LoopVectorize SLPVectorizer DeadStoreElimination AggressiveDCE CorrelatedValuePropagation IndVarSimplify These are part of the optimization pipeline, of which the legacy version is deprecated and being removed.
122 lines
3.5 KiB
C++
122 lines
3.5 KiB
C++
//===-- LLJITWithOptimizingIRTransform.cpp -- LLJIT with IR optimization --===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// In this example we will use an IR transform to optimize a module as it
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// passes through LLJIT's IRTransformLayer.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ExecutionEngine/Orc/LLJIT.h"
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#include "llvm/IR/LegacyPassManager.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/InitLLVM.h"
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#include "llvm/Support/TargetSelect.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Transforms/Scalar.h"
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#include "../ExampleModules.h"
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using namespace llvm;
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using namespace llvm::orc;
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ExitOnError ExitOnErr;
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// Example IR module.
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//
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// This IR contains a recursive definition of the factorial function:
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//
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// fac(n) | n == 0 = 1
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// | otherwise = n * fac(n - 1)
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//
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// It also contains an entry function which calls the factorial function with
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// an input value of 5.
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//
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// We expect the IR optimization transform that we build below to transform
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// this into a non-recursive factorial function and an entry function that
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// returns a constant value of 5!, or 120.
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const llvm::StringRef MainMod =
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R"(
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define i32 @fac(i32 %n) {
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entry:
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%tobool = icmp eq i32 %n, 0
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br i1 %tobool, label %return, label %if.then
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if.then: ; preds = %entry
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%arg = add nsw i32 %n, -1
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%call_result = call i32 @fac(i32 %arg)
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%result = mul nsw i32 %n, %call_result
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br label %return
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return: ; preds = %entry, %if.then
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%final_result = phi i32 [ %result, %if.then ], [ 1, %entry ]
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ret i32 %final_result
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}
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define i32 @entry() {
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entry:
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%result = call i32 @fac(i32 5)
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ret i32 %result
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}
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)";
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// A function object that creates a simple pass pipeline to apply to each
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// module as it passes through the IRTransformLayer.
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class MyOptimizationTransform {
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public:
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MyOptimizationTransform() : PM(std::make_unique<legacy::PassManager>()) {
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PM->add(createTailCallEliminationPass());
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PM->add(createCFGSimplificationPass());
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}
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Expected<ThreadSafeModule> operator()(ThreadSafeModule TSM,
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MaterializationResponsibility &R) {
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TSM.withModuleDo([this](Module &M) {
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dbgs() << "--- BEFORE OPTIMIZATION ---\n" << M << "\n";
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PM->run(M);
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dbgs() << "--- AFTER OPTIMIZATION ---\n" << M << "\n";
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});
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return std::move(TSM);
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}
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private:
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std::unique_ptr<legacy::PassManager> PM;
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};
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int main(int argc, char *argv[]) {
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// Initialize LLVM.
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InitLLVM X(argc, argv);
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InitializeNativeTarget();
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InitializeNativeTargetAsmPrinter();
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ExitOnErr.setBanner(std::string(argv[0]) + ": ");
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// (1) Create LLJIT instance.
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auto J = ExitOnErr(LLJITBuilder().create());
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// (2) Install transform to optimize modules when they're materialized.
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J->getIRTransformLayer().setTransform(MyOptimizationTransform());
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// (3) Add modules.
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ExitOnErr(J->addIRModule(ExitOnErr(parseExampleModule(MainMod, "MainMod"))));
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// (4) Look up the JIT'd function and call it.
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auto EntryAddr = ExitOnErr(J->lookup("entry"));
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auto *Entry = EntryAddr.toPtr<int()>();
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int Result = Entry();
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outs() << "--- Result ---\n"
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<< "entry() = " << Result << "\n";
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return 0;
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}
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