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llvm-project/llvm/unittests/Analysis/LoopNestTest.cpp

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//===- LoopNestTest.cpp - LoopNestAnalysis 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/AssumptionCache.h"
#include "llvm/Analysis/LoopNestAnalysis.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Dominators.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"
using namespace llvm;
/// Build the loop nest analysis for a loop nest and run the given test \p Test.
static void runTest(
Module &M, StringRef FuncName,
function_ref<void(Function &F, LoopInfo &LI, ScalarEvolution &SE)> Test) {
auto *F = M.getFunction(FuncName);
ASSERT_NE(F, nullptr) << "Could not find " << FuncName;
TargetLibraryInfoImpl TLII;
TargetLibraryInfo TLI(TLII);
AssumptionCache AC(*F);
DominatorTree DT(*F);
LoopInfo LI(DT);
ScalarEvolution SE(*F, TLI, AC, DT, LI);
Test(*F, LI, SE);
}
static std::unique_ptr<Module> makeLLVMModule(LLVMContext &Context,
const char *ModuleStr) {
SMDiagnostic Err;
return parseAssemblyString(ModuleStr, Err, Context);
}
static Instruction *getInstructionByName(Function &F, StringRef Name) {
for (BasicBlock &BB : F)
for (Instruction &I : BB)
if (I.getName() == Name)
return &I;
llvm_unreachable("Expected to find instruction!");
}
TEST(LoopNestTest, PerfectLoopNest) {
const char *ModuleStr =
"target datalayout = \"e-m:o-i64:64-f80:128-n8:16:32:64-S128\"\n"
"define void @foo(i64 signext %nx, i64 signext %ny) {\n"
"entry:\n"
" br label %for.outer\n"
"for.outer:\n"
" %i = phi i64 [ 0, %entry ], [ %inc13, %for.outer.latch ]\n"
" %cmp21 = icmp slt i64 0, %ny\n"
" br i1 %cmp21, label %for.inner.preheader, label %for.outer.latch\n"
"for.inner.preheader:\n"
" br label %for.inner\n"
"for.inner:\n"
" %j = phi i64 [ 0, %for.inner.preheader ], [ %inc, %for.inner.latch ]\n"
" br label %for.inner.latch\n"
"for.inner.latch:\n"
" %inc = add nsw i64 %j, 1\n"
" %cmp2 = icmp slt i64 %inc, %ny\n"
" br i1 %cmp2, label %for.inner, label %for.inner.exit\n"
"for.inner.exit:\n"
" br label %for.outer.latch\n"
"for.outer.latch:\n"
" %inc13 = add nsw i64 %i, 1\n"
" %cmp = icmp slt i64 %inc13, %nx\n"
" br i1 %cmp, label %for.outer, label %for.outer.exit\n"
"for.outer.exit:\n"
" br label %for.end\n"
"for.end:\n"
" ret void\n"
"}\n";
LLVMContext Context;
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleStr);
runTest(*M, "foo", [&](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
Function::iterator FI = F.begin();
// Skip the first basic block (entry), get to the outer loop header.
BasicBlock *Header = &*(++FI);
assert(Header->getName() == "for.outer");
Loop *L = LI.getLoopFor(Header);
EXPECT_NE(L, nullptr);
LoopNest LN(*L, SE);
EXPECT_TRUE(LN.areAllLoopsSimplifyForm());
// Ensure that we can identify the outermost loop in the nest.
const Loop &OL = LN.getOutermostLoop();
EXPECT_EQ(OL.getName(), "for.outer");
// Ensure that we can identify the innermost loop in the nest.
const Loop *IL = LN.getInnermostLoop();
EXPECT_NE(IL, nullptr);
EXPECT_EQ(IL->getName(), "for.inner");
// Ensure the loop nest is recognized as having 2 loops.
const ArrayRef<Loop*> Loops = LN.getLoops();
EXPECT_EQ(Loops.size(), 2ull);
// Ensure that we can obtain loops by depth.
LoopVectorTy LoopsAtDepth1 = LN.getLoopsAtDepth(1);
EXPECT_EQ(LoopsAtDepth1.size(), 1u);
EXPECT_EQ(LoopsAtDepth1[0], &OL);
LoopVectorTy LoopsAtDepth2 = LN.getLoopsAtDepth(2);
EXPECT_EQ(LoopsAtDepth2.size(), 1u);
EXPECT_EQ(LoopsAtDepth2[0], IL);
// Ensure that we can obtain the loop index of a given loop, and get back
// the loop with that index.
EXPECT_EQ(LN.getLoop(LN.getLoopIndex(OL)), &OL);
EXPECT_EQ(LN.getLoop(LN.getLoopIndex(*IL)), IL);
// Ensure the loop nest is recognized as perfect in its entirety.
const SmallVector<LoopVectorTy, 4> &PLV = LN.getPerfectLoops(SE);
EXPECT_EQ(PLV.size(), 1ull);
EXPECT_EQ(PLV.front().size(), 2ull);
// Ensure the nest depth and perfect nest depth are computed correctly.
EXPECT_EQ(LN.getNestDepth(), 2u);
EXPECT_EQ(LN.getMaxPerfectDepth(), 2u);
EXPECT_TRUE(LN.getInterveningInstructions(OL, *IL, SE).empty());
});
}
TEST(LoopNestTest, ImperfectLoopNest) {
const char *ModuleStr =
"target datalayout = \"e-m:o-i64:64-f80:128-n8:16:32:64-S128\"\n"
"define void @foo(i32 signext %nx, i32 signext %ny, i32 signext %nk) {\n"
"entry:\n"
" br label %loop.i\n"
"loop.i:\n"
" %i = phi i32 [ 0, %entry ], [ %inci, %for.inci ]\n"
" %cmp21 = icmp slt i32 0, %ny\n"
" br i1 %cmp21, label %loop.j.preheader, label %for.inci\n"
"loop.j.preheader:\n"
" br label %loop.j\n"
"loop.j:\n"
" %j = phi i32 [ %incj, %for.incj ], [ 0, %loop.j.preheader ]\n"
" %cmp22 = icmp slt i32 0, %nk\n"
" br i1 %cmp22, label %loop.k.preheader, label %for.incj\n"
"loop.k.preheader:\n"
" call void @bar()\n"
" br label %loop.k\n"
"loop.k:\n"
" %k = phi i32 [ %inck, %for.inck ], [ 0, %loop.k.preheader ]\n"
" br label %for.inck\n"
"for.inck:\n"
" %inck = add nsw i32 %k, 1\n"
" %cmp5 = icmp slt i32 %inck, %nk\n"
" br i1 %cmp5, label %loop.k, label %for.incj.loopexit\n"
"for.incj.loopexit:\n"
" br label %for.incj\n"
"for.incj:\n"
" %incj = add nsw i32 %j, 1\n"
" %cmp2 = icmp slt i32 %incj, %ny\n"
" br i1 %cmp2, label %loop.j, label %for.inci.loopexit\n"
"for.inci.loopexit:\n"
" br label %for.inci\n"
"for.inci:\n"
" %inci = add nsw i32 %i, 1\n"
" %cmp = icmp slt i32 %inci, %nx\n"
" br i1 %cmp, label %loop.i, label %loop.i.end\n"
"loop.i.end:\n"
" ret void\n"
"}\n"
"declare void @bar()\n";
LLVMContext Context;
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleStr);
runTest(*M, "foo", [&](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
Function::iterator FI = F.begin();
// Skip the first basic block (entry), get to the outermost loop header.
BasicBlock *Header = &*(++FI);
assert(Header->getName() == "loop.i");
Loop *L = LI.getLoopFor(Header);
EXPECT_NE(L, nullptr);
LoopNest LN(*L, SE);
EXPECT_TRUE(LN.areAllLoopsSimplifyForm());
dbgs() << "LN: " << LN << "\n";
// Ensure that we can identify the outermost loop in the nest.
const Loop &OL = LN.getOutermostLoop();
EXPECT_EQ(OL.getName(), "loop.i");
// Ensure that we can identify the innermost loop in the nest.
const Loop *IL = LN.getInnermostLoop();
EXPECT_NE(IL, nullptr);
EXPECT_EQ(IL->getName(), "loop.k");
// Ensure the loop nest is recognized as having 3 loops.
const ArrayRef<Loop*> Loops = LN.getLoops();
EXPECT_EQ(Loops.size(), 3ull);
// Ensure the loop nest is recognized as having 2 separate perfect loops groups.
const SmallVector<LoopVectorTy, 4> &PLV = LN.getPerfectLoops(SE);
EXPECT_EQ(PLV.size(), 2ull);
EXPECT_EQ(PLV.front().size(), 2ull);
EXPECT_EQ(PLV.back().size(), 1ull);
// Ensure the nest depth and perfect nest depth are computed correctly.
EXPECT_EQ(LN.getNestDepth(), 3u);
EXPECT_EQ(LN.getMaxPerfectDepth(), 2u);
EXPECT_TRUE(LN.getInterveningInstructions(OL, *IL, SE).empty());
});
}
TEST(LoopNestTest, InterveningInstrLoopNest) {
const char *ModuleStr =
"target datalayout = \"e-m:o-i64:64-f80:128-n8:16:32:64-S128\"\n"
"define void @foo(i64 signext %nx, i64 signext %ny, i32* noalias %A, i32 "
"%op0, i32 %op1){\n"
"entry:\n"
" br label %for.outer\n"
"for.outer:\n"
" %i = phi i64 [ 0, %entry ], [ %inc13, %for.outer.latch ]\n"
" %cmp21 = icmp slt i64 0, %ny\n"
" call void @outerheader()\n"
" br i1 %cmp21, label %for.inner.preheader, label %for.outer.latch\n"
"for.inner.preheader:\n"
" %varr = getelementptr inbounds i32, i32* %A, i64 5\n"
" store i32 5, i32* %varr, align 4\n"
" call void @innerpreheader()\n"
" br label %for.inner\n"
"for.inner:\n"
" %j = phi i64 [ 0, %for.inner.preheader ], [ %inc, %for.inner.latch ]\n"
" br label %for.inner.latch\n"
"for.inner.latch:\n"
" %inc = add nsw i64 %j, 1\n"
" %cmp2 = icmp slt i64 %inc, %ny\n"
" br i1 %cmp2, label %for.inner, label %for.inner.exit\n"
"for.inner.exit:\n"
" %varr1 = getelementptr inbounds i32, i32* %A, i64 5\n"
" call void @innerexit()\n"
" br label %for.outer.latch\n"
"for.outer.latch:\n"
" %inc13 = add nsw i64 %i, 1\n"
" call void @outerlatch()\n"
" %cmp = icmp slt i64 %inc13, %nx\n"
" br i1 %cmp, label %for.outer, label %for.outer.exit\n"
"for.outer.exit:\n"
" br label %for.end\n"
"for.end:\n"
" ret void\n"
"}\n"
"declare void @innerpreheader()\n"
"declare void @outerheader()\n"
"declare void @outerlatch()\n"
"declare void @innerexit()\n";
LLVMContext Context;
std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleStr);
runTest(*M, "foo", [&](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
Function::iterator FI = F.begin();
// Skip the first basic block (entry), get to the outer loop header.
BasicBlock *Header = &*(++FI);
assert(Header->getName() == "for.outer");
Loop *L = LI.getLoopFor(Header);
EXPECT_NE(L, nullptr);
LoopNest LN(*L, SE);
EXPECT_TRUE(LN.areAllLoopsSimplifyForm());
// Ensure that we can identify the outermost loop in the nest.
const Loop &OL = LN.getOutermostLoop();
EXPECT_EQ(OL.getName(), "for.outer");
// Ensure that we can identify the innermost loop in the nest.
const Loop *IL = LN.getInnermostLoop();
EXPECT_NE(IL, nullptr);
EXPECT_EQ(IL->getName(), "for.inner");
// Ensure the loop nest is recognized as having 2 loops.
const ArrayRef<Loop *> Loops = LN.getLoops();
EXPECT_EQ(Loops.size(), 2ull);
// Ensure the loop nest is not recognized as perfect in its entirety.
const SmallVector<LoopVectorTy, 4> &PLV = LN.getPerfectLoops(SE);
EXPECT_EQ(PLV.size(), 2ull);
EXPECT_EQ(PLV.front().size(), 1ull);
EXPECT_EQ(PLV.back().size(), 1ull);
// Ensure the nest depth and perfect nest depth are computed correctly.
EXPECT_EQ(LN.getNestDepth(), 2u);
EXPECT_EQ(LN.getMaxPerfectDepth(), 1u);
// Ensure enclosed instructions are recognized
const LoopNest::InstrVectorTy InstrV =
LN.getInterveningInstructions(OL, *IL, SE);
EXPECT_EQ(InstrV.size(), 5u);
Instruction *SI = getInstructionByName(F, "varr")->getNextNode();
Instruction *CI = SI->getNextNode();
Instruction *OLH =
getInstructionByName(F, "i")->getNextNode()->getNextNode();
Instruction *OLL = getInstructionByName(F, "inc13")->getNextNode();
Instruction *IE = getInstructionByName(F, "varr1")->getNextNode();
EXPECT_EQ(InstrV.front(), OLH);
EXPECT_EQ(InstrV[1], OLL);
EXPECT_EQ(InstrV[2], IE);
EXPECT_EQ(InstrV[3], SI);
EXPECT_EQ(InstrV.back(), CI);
});
}
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