LICMTest.cpp
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//===- LICMTest.cpp - LICM unit tests -------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Module.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Testing/Support/Error.h"
#include "llvm/Transforms/Scalar/LICM.h"
#include "gtest/gtest.h"
namespace llvm {
TEST(LICMTest, TestSCEVInvalidationOnHoisting) {
LLVMContext Ctx;
ModulePassManager MPM;
PassBuilder PB;
LoopAnalysisManager LAM;
FunctionAnalysisManager FAM;
CGSCCAnalysisManager CGAM;
ModuleAnalysisManager MAM;
PB.registerModuleAnalyses(MAM);
PB.registerCGSCCAnalyses(CGAM);
PB.registerFunctionAnalyses(FAM);
PB.registerLoopAnalyses(LAM);
PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
StringRef PipelineStr = "require<opt-remark-emit>,loop(licm)";
ASSERT_THAT_ERROR(PB.parsePassPipeline(MPM, PipelineStr), Succeeded());
SMDiagnostic Error;
StringRef Text = R"(
define void @foo(i64* %ptr) {
entry:
br label %loop
loop:
%iv = phi i64 [ 0, %entry ], [ %iv.inc, %loop ]
%n = load i64, i64* %ptr, !invariant.load !0
%iv.inc = add i64 %iv, 1
%cmp = icmp ult i64 %iv.inc, %n
br i1 %cmp, label %loop, label %exit
exit:
ret void
}
!0 = !{}
)";
std::unique_ptr<Module> M = parseAssemblyString(Text, Error, Ctx);
ASSERT_TRUE(M);
Function *F = M->getFunction("foo");
ScalarEvolution &SE = FAM.getResult<ScalarEvolutionAnalysis>(*F);
BasicBlock &EntryBB = F->getEntryBlock();
BasicBlock *LoopBB = EntryBB.getUniqueSuccessor();
// Select `load i64, i64* %ptr`.
Instruction *IBefore = LoopBB->getFirstNonPHI();
// Make sure the right instruction was selected.
ASSERT_TRUE(isa<LoadInst>(IBefore));
// Upon this query SCEV caches disposition of <load i64, i64* %ptr> SCEV.
ASSERT_EQ(SE.getBlockDisposition(SE.getSCEV(IBefore), LoopBB),
ScalarEvolution::BlockDisposition::DominatesBlock);
MPM.run(*M, MAM);
// Select `load i64, i64* %ptr` after it was hoisted.
Instruction *IAfter = EntryBB.getFirstNonPHI();
// Make sure the right instruction was selected.
ASSERT_TRUE(isa<LoadInst>(IAfter));
ScalarEvolution::BlockDisposition DispositionBeforeInvalidation =
SE.getBlockDisposition(SE.getSCEV(IAfter), LoopBB);
SE.forgetValue(IAfter);
ScalarEvolution::BlockDisposition DispositionAfterInvalidation =
SE.getBlockDisposition(SE.getSCEV(IAfter), LoopBB);
// If LICM have properly invalidated SCEV,
// 1. SCEV of <load i64, i64* %ptr> should properly dominate the "loop" BB,
// 2. extra invalidation shouldn't change result of the query.
EXPECT_EQ(DispositionBeforeInvalidation,
ScalarEvolution::BlockDisposition::ProperlyDominatesBlock);
EXPECT_EQ(DispositionBeforeInvalidation, DispositionAfterInvalidation);
}
}