llvm/unittests/Analysis/LazyCallGraphTest.cpp
Chandler Carruth b9619110af [LCG] Implement Tarjan's algorithm correctly this time. We have to walk
up the stack finishing the exploration of each entries children before
we're finished in addition to accounting for their low-links. Added
a unittest that really hammers home the need for this with interlocking
cycles that would each appear distinct otherwise and crash or compute
the wrong result. As part of this, nuke a stale fixme and bring the rest
of the implementation still more closely in line with the original
algorithm.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206966 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-23 10:31:17 +00:00

309 lines
8.8 KiB
C++

//===- LazyCallGraphTest.cpp - Unit tests for the lazy CG analysis --------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LazyCallGraph.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"
#include <memory>
using namespace llvm;
namespace {
std::unique_ptr<Module> parseAssembly(const char *Assembly) {
auto M = make_unique<Module>("Module", getGlobalContext());
SMDiagnostic Error;
bool Parsed =
ParseAssemblyString(Assembly, M.get(), Error, M->getContext()) == M.get();
std::string ErrMsg;
raw_string_ostream OS(ErrMsg);
Error.print("", OS);
// A failure here means that the test itself is buggy.
if (!Parsed)
report_fatal_error(OS.str().c_str());
return M;
}
// IR forming a call graph with a diamond of triangle-shaped SCCs:
//
// d1
// / \
// d3--d2
// / \
// b1 c1
// / \ / \
// b3--b2 c3--c2
// \ /
// a1
// / \
// a3--a2
//
// All call edges go up between SCCs, and clockwise around the SCC.
static const char DiamondOfTriangles[] =
"define void @a1() {\n"
"entry:\n"
" call void @a2()\n"
" call void @b2()\n"
" call void @c3()\n"
" ret void\n"
"}\n"
"define void @a2() {\n"
"entry:\n"
" call void @a3()\n"
" ret void\n"
"}\n"
"define void @a3() {\n"
"entry:\n"
" call void @a1()\n"
" ret void\n"
"}\n"
"define void @b1() {\n"
"entry:\n"
" call void @b2()\n"
" call void @d3()\n"
" ret void\n"
"}\n"
"define void @b2() {\n"
"entry:\n"
" call void @b3()\n"
" ret void\n"
"}\n"
"define void @b3() {\n"
"entry:\n"
" call void @b1()\n"
" ret void\n"
"}\n"
"define void @c1() {\n"
"entry:\n"
" call void @c2()\n"
" call void @d2()\n"
" ret void\n"
"}\n"
"define void @c2() {\n"
"entry:\n"
" call void @c3()\n"
" ret void\n"
"}\n"
"define void @c3() {\n"
"entry:\n"
" call void @c1()\n"
" ret void\n"
"}\n"
"define void @d1() {\n"
"entry:\n"
" call void @d2()\n"
" ret void\n"
"}\n"
"define void @d2() {\n"
"entry:\n"
" call void @d3()\n"
" ret void\n"
"}\n"
"define void @d3() {\n"
"entry:\n"
" call void @d1()\n"
" ret void\n"
"}\n";
TEST(LazyCallGraphTest, BasicGraphFormation) {
std::unique_ptr<Module> M = parseAssembly(DiamondOfTriangles);
LazyCallGraph CG(*M);
// The order of the entry nodes should be stable w.r.t. the source order of
// the IR, and everything in our module is an entry node, so just directly
// build variables for each node.
auto I = CG.begin();
LazyCallGraph::Node *A1 = *I++;
EXPECT_EQ("a1", A1->getFunction().getName());
LazyCallGraph::Node *A2 = *I++;
EXPECT_EQ("a2", A2->getFunction().getName());
LazyCallGraph::Node *A3 = *I++;
EXPECT_EQ("a3", A3->getFunction().getName());
LazyCallGraph::Node *B1 = *I++;
EXPECT_EQ("b1", B1->getFunction().getName());
LazyCallGraph::Node *B2 = *I++;
EXPECT_EQ("b2", B2->getFunction().getName());
LazyCallGraph::Node *B3 = *I++;
EXPECT_EQ("b3", B3->getFunction().getName());
LazyCallGraph::Node *C1 = *I++;
EXPECT_EQ("c1", C1->getFunction().getName());
LazyCallGraph::Node *C2 = *I++;
EXPECT_EQ("c2", C2->getFunction().getName());
LazyCallGraph::Node *C3 = *I++;
EXPECT_EQ("c3", C3->getFunction().getName());
LazyCallGraph::Node *D1 = *I++;
EXPECT_EQ("d1", D1->getFunction().getName());
LazyCallGraph::Node *D2 = *I++;
EXPECT_EQ("d2", D2->getFunction().getName());
LazyCallGraph::Node *D3 = *I++;
EXPECT_EQ("d3", D3->getFunction().getName());
EXPECT_EQ(CG.end(), I);
// Build vectors and sort them for the rest of the assertions to make them
// independent of order.
std::vector<std::string> Nodes;
for (LazyCallGraph::Node *N : *A1)
Nodes.push_back(N->getFunction().getName());
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ("a2", Nodes[0]);
EXPECT_EQ("b2", Nodes[1]);
EXPECT_EQ("c3", Nodes[2]);
Nodes.clear();
EXPECT_EQ(A2->end(), std::next(A2->begin()));
EXPECT_EQ("a3", A2->begin()->getFunction().getName());
EXPECT_EQ(A3->end(), std::next(A3->begin()));
EXPECT_EQ("a1", A3->begin()->getFunction().getName());
for (LazyCallGraph::Node *N : *B1)
Nodes.push_back(N->getFunction().getName());
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ("b2", Nodes[0]);
EXPECT_EQ("d3", Nodes[1]);
Nodes.clear();
EXPECT_EQ(B2->end(), std::next(B2->begin()));
EXPECT_EQ("b3", B2->begin()->getFunction().getName());
EXPECT_EQ(B3->end(), std::next(B3->begin()));
EXPECT_EQ("b1", B3->begin()->getFunction().getName());
for (LazyCallGraph::Node *N : *C1)
Nodes.push_back(N->getFunction().getName());
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ("c2", Nodes[0]);
EXPECT_EQ("d2", Nodes[1]);
Nodes.clear();
EXPECT_EQ(C2->end(), std::next(C2->begin()));
EXPECT_EQ("c3", C2->begin()->getFunction().getName());
EXPECT_EQ(C3->end(), std::next(C3->begin()));
EXPECT_EQ("c1", C3->begin()->getFunction().getName());
EXPECT_EQ(D1->end(), std::next(D1->begin()));
EXPECT_EQ("d2", D1->begin()->getFunction().getName());
EXPECT_EQ(D2->end(), std::next(D2->begin()));
EXPECT_EQ("d3", D2->begin()->getFunction().getName());
EXPECT_EQ(D3->end(), std::next(D3->begin()));
EXPECT_EQ("d1", D3->begin()->getFunction().getName());
// Now lets look at the SCCs.
auto SCCI = CG.postorder_scc_begin();
LazyCallGraph::SCC *D = *SCCI++;
for (LazyCallGraph::Node *N : *D)
Nodes.push_back(N->getFunction().getName());
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ("d1", Nodes[0]);
EXPECT_EQ("d2", Nodes[1]);
EXPECT_EQ("d3", Nodes[2]);
EXPECT_EQ(3u, Nodes.size());
Nodes.clear();
LazyCallGraph::SCC *C = *SCCI++;
for (LazyCallGraph::Node *N : *C)
Nodes.push_back(N->getFunction().getName());
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ("c1", Nodes[0]);
EXPECT_EQ("c2", Nodes[1]);
EXPECT_EQ("c3", Nodes[2]);
EXPECT_EQ(3u, Nodes.size());
Nodes.clear();
LazyCallGraph::SCC *B = *SCCI++;
for (LazyCallGraph::Node *N : *B)
Nodes.push_back(N->getFunction().getName());
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ("b1", Nodes[0]);
EXPECT_EQ("b2", Nodes[1]);
EXPECT_EQ("b3", Nodes[2]);
EXPECT_EQ(3u, Nodes.size());
Nodes.clear();
LazyCallGraph::SCC *A = *SCCI++;
for (LazyCallGraph::Node *N : *A)
Nodes.push_back(N->getFunction().getName());
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ("a1", Nodes[0]);
EXPECT_EQ("a2", Nodes[1]);
EXPECT_EQ("a3", Nodes[2]);
EXPECT_EQ(3u, Nodes.size());
Nodes.clear();
EXPECT_EQ(CG.postorder_scc_end(), SCCI);
}
static Function &lookupFunction(Module &M, StringRef Name) {
for (Function &F : M)
if (F.getName() == Name)
return F;
report_fatal_error("Couldn't find function!");
}
TEST(LazyCallGraphTest, MultiArmSCC) {
// Two interlocking cycles. The really useful thing about this SCC is that it
// will require Tarjan's DFS to backtrack and finish processing all of the
// children of each node in the SCC.
std::unique_ptr<Module> M = parseAssembly(
"define void @a() {\n"
"entry:\n"
" call void @b()\n"
" call void @d()\n"
" ret void\n"
"}\n"
"define void @b() {\n"
"entry:\n"
" call void @c()\n"
" ret void\n"
"}\n"
"define void @c() {\n"
"entry:\n"
" call void @a()\n"
" ret void\n"
"}\n"
"define void @d() {\n"
"entry:\n"
" call void @e()\n"
" ret void\n"
"}\n"
"define void @e() {\n"
"entry:\n"
" call void @a()\n"
" ret void\n"
"}\n");
LazyCallGraph CG(*M);
// Force the graph to be fully expanded.
auto SCCI = CG.postorder_scc_begin();
LazyCallGraph::SCC *SCC = *SCCI++;
EXPECT_EQ(CG.postorder_scc_end(), SCCI);
LazyCallGraph::Node *A = CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node *B = CG.lookup(lookupFunction(*M, "b"));
LazyCallGraph::Node *C = CG.lookup(lookupFunction(*M, "c"));
LazyCallGraph::Node *D = CG.lookup(lookupFunction(*M, "d"));
LazyCallGraph::Node *E = CG.lookup(lookupFunction(*M, "e"));
EXPECT_EQ(SCC, CG.lookupSCC(A->getFunction()));
EXPECT_EQ(SCC, CG.lookupSCC(B->getFunction()));
EXPECT_EQ(SCC, CG.lookupSCC(C->getFunction()));
EXPECT_EQ(SCC, CG.lookupSCC(D->getFunction()));
EXPECT_EQ(SCC, CG.lookupSCC(E->getFunction()));
}
}