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v8/test/unittests/compiler/loop-peeling-unittest.cc
titzer 0b4dfc2312 [turbofan] Rework handling of loop exits in loop peeling. 
This CL primarily makes the loop peeling algorithm more robust; it no longer damages the graph if the loops are improperly closed.

R=bmeurer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1052753004

Cr-Commit-Position: refs/heads/master@{#27620}
2015-04-07 11:00:47 +00:00

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// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/compiler/access-builder.h"
#include "src/compiler/graph.h"
#include "src/compiler/graph-visualizer.h"
#include "src/compiler/js-graph.h"
#include "src/compiler/loop-peeling.h"
#include "src/compiler/machine-operator.h"
#include "src/compiler/node.h"
#include "src/compiler/node-properties.h"
#include "test/unittests/compiler/compiler-test-utils.h"
#include "test/unittests/compiler/graph-unittest.h"
#include "test/unittests/compiler/node-test-utils.h"
#include "testing/gmock-support.h"
using testing::AllOf;
using testing::BitEq;
using testing::Capture;
using testing::CaptureEq;
namespace v8 {
namespace internal {
namespace compiler {
struct While {
Node* loop;
Node* branch;
Node* if_true;
Node* exit;
};
// A helper for building branches.
struct Branch {
Node* branch;
Node* if_true;
Node* if_false;
};
// A helper for building counters attached to loops.
struct Counter {
Node* base;
Node* inc;
Node* phi;
Node* add;
};
class LoopPeelingTest : public GraphTest {
public:
LoopPeelingTest() : GraphTest(1), machine_(zone()) {}
~LoopPeelingTest() OVERRIDE {}
protected:
MachineOperatorBuilder machine_;
MachineOperatorBuilder* machine() { return &machine_; }
LoopTree* GetLoopTree() {
if (FLAG_trace_turbo_graph) {
OFStream os(stdout);
os << AsRPO(*graph());
}
Zone zone;
return LoopFinder::BuildLoopTree(graph(), &zone);
}
PeeledIteration* PeelOne() {
LoopTree* loop_tree = GetLoopTree();
LoopTree::Loop* loop = loop_tree->outer_loops()[0];
EXPECT_TRUE(LoopPeeler::CanPeel(loop_tree, loop));
return Peel(loop_tree, loop);
}
PeeledIteration* Peel(LoopTree* loop_tree, LoopTree::Loop* loop) {
EXPECT_TRUE(LoopPeeler::CanPeel(loop_tree, loop));
PeeledIteration* peeled =
LoopPeeler::Peel(graph(), common(), loop_tree, loop, zone());
if (FLAG_trace_turbo_graph) {
OFStream os(stdout);
os << AsRPO(*graph());
}
return peeled;
}
Node* InsertReturn(Node* val, Node* effect, Node* control) {
Node* r = graph()->NewNode(common()->Return(), val, effect, control);
graph()->SetEnd(r);
return r;
}
Node* ExpectPeeled(Node* node, PeeledIteration* iter) {
Node* p = iter->map(node);
EXPECT_NE(node, p);
return p;
}
void ExpectNotPeeled(Node* node, PeeledIteration* iter) {
EXPECT_EQ(node, iter->map(node));
}
While NewWhile(Node* cond, Node* control = nullptr) {
if (control == nullptr) control = start();
Node* loop = graph()->NewNode(common()->Loop(2), control, control);
Node* branch = graph()->NewNode(common()->Branch(), cond, loop);
Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
Node* exit = graph()->NewNode(common()->IfFalse(), branch);
loop->ReplaceInput(1, if_true);
return {loop, branch, if_true, exit};
}
void Chain(While* a, Node* control) { a->loop->ReplaceInput(0, control); }
void Nest(While* a, While* b) {
b->loop->ReplaceInput(1, a->exit);
a->loop->ReplaceInput(0, b->if_true);
}
Node* NewPhi(While* w, Node* a, Node* b) {
return graph()->NewNode(common()->Phi(kMachAnyTagged, 2), a, b, w->loop);
}
Branch NewBranch(Node* cond, Node* control = nullptr) {
if (control == nullptr) control = start();
Node* branch = graph()->NewNode(common()->Branch(), cond, control);
Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
return {branch, if_true, if_false};
}
Counter NewCounter(While* w, int32_t b, int32_t k) {
Node* base = Int32Constant(b);
Node* inc = Int32Constant(k);
Node* phi =
graph()->NewNode(common()->Phi(kMachAnyTagged, 2), base, base, w->loop);
Node* add = graph()->NewNode(machine()->Int32Add(), phi, inc);
phi->ReplaceInput(1, add);
return {base, inc, phi, add};
}
};
TEST_F(LoopPeelingTest, SimpleLoop) {
Node* p0 = Parameter(0);
While w = NewWhile(p0);
Node* r = InsertReturn(p0, start(), w.exit);
PeeledIteration* peeled = PeelOne();
Node* br1 = ExpectPeeled(w.branch, peeled);
Node* if_true1 = ExpectPeeled(w.if_true, peeled);
Node* if_false1 = ExpectPeeled(w.exit, peeled);
EXPECT_THAT(br1, IsBranch(p0, start()));
EXPECT_THAT(if_true1, IsIfTrue(br1));
EXPECT_THAT(if_false1, IsIfFalse(br1));
EXPECT_THAT(w.loop, IsLoop(if_true1, w.if_true));
EXPECT_THAT(r, IsReturn(p0, start(), IsMerge(w.exit, if_false1)));
}
TEST_F(LoopPeelingTest, SimpleLoopWithCounter) {
Node* p0 = Parameter(0);
While w = NewWhile(p0);
Counter c = NewCounter(&w, 0, 1);
Node* r = InsertReturn(c.phi, start(), w.exit);
PeeledIteration* peeled = PeelOne();
Node* br1 = ExpectPeeled(w.branch, peeled);
Node* if_true1 = ExpectPeeled(w.if_true, peeled);
Node* if_false1 = ExpectPeeled(w.exit, peeled);
EXPECT_THAT(br1, IsBranch(p0, start()));
EXPECT_THAT(if_true1, IsIfTrue(br1));
EXPECT_THAT(if_false1, IsIfFalse(br1));
EXPECT_THAT(w.loop, IsLoop(if_true1, w.if_true));
EXPECT_THAT(peeled->map(c.add), IsInt32Add(c.base, c.inc));
Capture<Node*> merge;
EXPECT_THAT(
r, IsReturn(IsPhi(kMachAnyTagged, c.phi, c.base,
AllOf(CaptureEq(&merge), IsMerge(w.exit, if_false1))),
start(), CaptureEq(&merge)));
}
TEST_F(LoopPeelingTest, SimpleNestedLoopWithCounter_peel_outer) {
Node* p0 = Parameter(0);
While outer = NewWhile(p0);
While inner = NewWhile(p0);
Nest(&inner, &outer);
Counter c = NewCounter(&outer, 0, 1);
Node* r = InsertReturn(c.phi, start(), outer.exit);
PeeledIteration* peeled = PeelOne();
Node* bro = ExpectPeeled(outer.branch, peeled);
Node* if_trueo = ExpectPeeled(outer.if_true, peeled);
Node* if_falseo = ExpectPeeled(outer.exit, peeled);
EXPECT_THAT(bro, IsBranch(p0, start()));
EXPECT_THAT(if_trueo, IsIfTrue(bro));
EXPECT_THAT(if_falseo, IsIfFalse(bro));
Node* bri = ExpectPeeled(inner.branch, peeled);
Node* if_truei = ExpectPeeled(inner.if_true, peeled);
Node* if_falsei = ExpectPeeled(inner.exit, peeled);
EXPECT_THAT(bri, IsBranch(p0, ExpectPeeled(inner.loop, peeled)));
EXPECT_THAT(if_truei, IsIfTrue(bri));
EXPECT_THAT(if_falsei, IsIfFalse(bri));
EXPECT_THAT(outer.loop, IsLoop(if_falsei, inner.exit));
EXPECT_THAT(peeled->map(c.add), IsInt32Add(c.base, c.inc));
Capture<Node*> merge;
EXPECT_THAT(
r,
IsReturn(IsPhi(kMachAnyTagged, c.phi, c.base,
AllOf(CaptureEq(&merge), IsMerge(outer.exit, if_falseo))),
start(), CaptureEq(&merge)));
}
TEST_F(LoopPeelingTest, SimpleNestedLoopWithCounter_peel_inner) {
Node* p0 = Parameter(0);
While outer = NewWhile(p0);
While inner = NewWhile(p0);
Nest(&inner, &outer);
Counter c = NewCounter(&outer, 0, 1);
Node* r = InsertReturn(c.phi, start(), outer.exit);
LoopTree* loop_tree = GetLoopTree();
LoopTree::Loop* loop = loop_tree->ContainingLoop(inner.loop);
EXPECT_NE(nullptr, loop);
EXPECT_EQ(1u, loop->depth());
PeeledIteration* peeled = Peel(loop_tree, loop);
ExpectNotPeeled(outer.loop, peeled);
ExpectNotPeeled(outer.branch, peeled);
ExpectNotPeeled(outer.if_true, peeled);
ExpectNotPeeled(outer.exit, peeled);
Node* bri = ExpectPeeled(inner.branch, peeled);
Node* if_truei = ExpectPeeled(inner.if_true, peeled);
Node* if_falsei = ExpectPeeled(inner.exit, peeled);
EXPECT_THAT(bri, IsBranch(p0, ExpectPeeled(inner.loop, peeled)));
EXPECT_THAT(if_truei, IsIfTrue(bri));
EXPECT_THAT(if_falsei, IsIfFalse(bri));
EXPECT_THAT(outer.loop, IsLoop(start(), IsMerge(inner.exit, if_falsei)));
ExpectNotPeeled(c.add, peeled);
EXPECT_THAT(r, IsReturn(c.phi, start(), outer.exit));
}
TEST_F(LoopPeelingTest, SimpleInnerCounter_peel_inner) {
Node* p0 = Parameter(0);
While outer = NewWhile(p0);
While inner = NewWhile(p0);
Nest(&inner, &outer);
Counter c = NewCounter(&inner, 0, 1);
Node* phi = NewPhi(&outer, Int32Constant(11), c.phi);
Node* r = InsertReturn(phi, start(), outer.exit);
LoopTree* loop_tree = GetLoopTree();
LoopTree::Loop* loop = loop_tree->ContainingLoop(inner.loop);
EXPECT_NE(nullptr, loop);
EXPECT_EQ(1u, loop->depth());
PeeledIteration* peeled = Peel(loop_tree, loop);
ExpectNotPeeled(outer.loop, peeled);
ExpectNotPeeled(outer.branch, peeled);
ExpectNotPeeled(outer.if_true, peeled);
ExpectNotPeeled(outer.exit, peeled);
Node* bri = ExpectPeeled(inner.branch, peeled);
Node* if_truei = ExpectPeeled(inner.if_true, peeled);
Node* if_falsei = ExpectPeeled(inner.exit, peeled);
EXPECT_THAT(bri, IsBranch(p0, ExpectPeeled(inner.loop, peeled)));
EXPECT_THAT(if_truei, IsIfTrue(bri));
EXPECT_THAT(if_falsei, IsIfFalse(bri));
EXPECT_THAT(outer.loop, IsLoop(start(), IsMerge(inner.exit, if_falsei)));
EXPECT_THAT(peeled->map(c.add), IsInt32Add(c.base, c.inc));
Node* back = phi->InputAt(1);
EXPECT_THAT(back, IsPhi(kMachAnyTagged, c.phi, c.base,
IsMerge(inner.exit, if_falsei)));
EXPECT_THAT(phi,
IsPhi(kMachAnyTagged, IsInt32Constant(11), back, outer.loop));
EXPECT_THAT(r, IsReturn(phi, start(), outer.exit));
}
TEST_F(LoopPeelingTest, TwoBackedgeLoop) {
Node* p0 = Parameter(0);
Node* loop = graph()->NewNode(common()->Loop(3), start(), start(), start());
Branch b1 = NewBranch(p0, loop);
Branch b2 = NewBranch(p0, b1.if_true);
loop->ReplaceInput(1, b2.if_true);
loop->ReplaceInput(2, b2.if_false);
Node* r = InsertReturn(p0, start(), b1.if_false);
PeeledIteration* peeled = PeelOne();
Node* b1b = ExpectPeeled(b1.branch, peeled);
Node* b1t = ExpectPeeled(b1.if_true, peeled);
Node* b1f = ExpectPeeled(b1.if_false, peeled);
EXPECT_THAT(b1b, IsBranch(p0, start()));
EXPECT_THAT(ExpectPeeled(b1.if_true, peeled), IsIfTrue(b1b));
EXPECT_THAT(b1f, IsIfFalse(b1b));
Node* b2b = ExpectPeeled(b2.branch, peeled);
Node* b2t = ExpectPeeled(b2.if_true, peeled);
Node* b2f = ExpectPeeled(b2.if_false, peeled);
EXPECT_THAT(b2b, IsBranch(p0, b1t));
EXPECT_THAT(b2t, IsIfTrue(b2b));
EXPECT_THAT(b2f, IsIfFalse(b2b));
EXPECT_THAT(loop, IsLoop(IsMerge(b2t, b2f), b2.if_true, b2.if_false));
EXPECT_THAT(r, IsReturn(p0, start(), IsMerge(b1.if_false, b1f)));
}
TEST_F(LoopPeelingTest, TwoBackedgeLoopWithPhi) {
Node* p0 = Parameter(0);
Node* loop = graph()->NewNode(common()->Loop(3), start(), start(), start());
Branch b1 = NewBranch(p0, loop);
Branch b2 = NewBranch(p0, b1.if_true);
Node* phi =
graph()->NewNode(common()->Phi(kMachAnyTagged, 3), Int32Constant(0),
Int32Constant(1), Int32Constant(2), loop);
loop->ReplaceInput(1, b2.if_true);
loop->ReplaceInput(2, b2.if_false);
Node* r = InsertReturn(phi, start(), b1.if_false);
PeeledIteration* peeled = PeelOne();
Node* b1b = ExpectPeeled(b1.branch, peeled);
Node* b1t = ExpectPeeled(b1.if_true, peeled);
Node* b1f = ExpectPeeled(b1.if_false, peeled);
EXPECT_THAT(b1b, IsBranch(p0, start()));
EXPECT_THAT(ExpectPeeled(b1.if_true, peeled), IsIfTrue(b1b));
EXPECT_THAT(b1f, IsIfFalse(b1b));
Node* b2b = ExpectPeeled(b2.branch, peeled);
Node* b2t = ExpectPeeled(b2.if_true, peeled);
Node* b2f = ExpectPeeled(b2.if_false, peeled);
EXPECT_THAT(b2b, IsBranch(p0, b1t));
EXPECT_THAT(b2t, IsIfTrue(b2b));
EXPECT_THAT(b2f, IsIfFalse(b2b));
EXPECT_THAT(loop, IsLoop(IsMerge(b2t, b2f), b2.if_true, b2.if_false));
EXPECT_THAT(
phi, IsPhi(kMachAnyTagged, IsPhi(kMachAnyTagged, IsInt32Constant(1),
IsInt32Constant(2), IsMerge(b2t, b2f)),
IsInt32Constant(1), IsInt32Constant(2), loop));
Capture<Node*> merge;
EXPECT_THAT(
r, IsReturn(IsPhi(kMachAnyTagged, phi, IsInt32Constant(0),
AllOf(CaptureEq(&merge), IsMerge(b1.if_false, b1f))),
start(), CaptureEq(&merge)));
}
TEST_F(LoopPeelingTest, TwoBackedgeLoopWithCounter) {
Node* p0 = Parameter(0);
Node* loop = graph()->NewNode(common()->Loop(3), start(), start(), start());
Branch b1 = NewBranch(p0, loop);
Branch b2 = NewBranch(p0, b1.if_true);
Node* phi =
graph()->NewNode(common()->Phi(kMachAnyTagged, 3), Int32Constant(0),
Int32Constant(1), Int32Constant(2), loop);
phi->ReplaceInput(
1, graph()->NewNode(machine()->Int32Add(), phi, Int32Constant(1)));
phi->ReplaceInput(
2, graph()->NewNode(machine()->Int32Add(), phi, Int32Constant(2)));
loop->ReplaceInput(1, b2.if_true);
loop->ReplaceInput(2, b2.if_false);
Node* r = InsertReturn(phi, start(), b1.if_false);
PeeledIteration* peeled = PeelOne();
Node* b1b = ExpectPeeled(b1.branch, peeled);
Node* b1t = ExpectPeeled(b1.if_true, peeled);
Node* b1f = ExpectPeeled(b1.if_false, peeled);
EXPECT_THAT(b1b, IsBranch(p0, start()));
EXPECT_THAT(ExpectPeeled(b1.if_true, peeled), IsIfTrue(b1b));
EXPECT_THAT(b1f, IsIfFalse(b1b));
Node* b2b = ExpectPeeled(b2.branch, peeled);
Node* b2t = ExpectPeeled(b2.if_true, peeled);
Node* b2f = ExpectPeeled(b2.if_false, peeled);
EXPECT_THAT(b2b, IsBranch(p0, b1t));
EXPECT_THAT(b2t, IsIfTrue(b2b));
EXPECT_THAT(b2f, IsIfFalse(b2b));
Capture<Node*> entry;
EXPECT_THAT(loop, IsLoop(AllOf(CaptureEq(&entry), IsMerge(b2t, b2f)),
b2.if_true, b2.if_false));
Node* eval = phi->InputAt(0);
EXPECT_THAT(eval, IsPhi(kMachAnyTagged,
IsInt32Add(IsInt32Constant(0), IsInt32Constant(1)),
IsInt32Add(IsInt32Constant(0), IsInt32Constant(2)),
CaptureEq(&entry)));
EXPECT_THAT(phi,
IsPhi(kMachAnyTagged, eval, IsInt32Add(phi, IsInt32Constant(1)),
IsInt32Add(phi, IsInt32Constant(2)), loop));
Capture<Node*> merge;
EXPECT_THAT(
r, IsReturn(IsPhi(kMachAnyTagged, phi, IsInt32Constant(0),
AllOf(CaptureEq(&merge), IsMerge(b1.if_false, b1f))),
start(), CaptureEq(&merge)));
}
TEST_F(LoopPeelingTest, TwoExitLoop_nope) {
Node* p0 = Parameter(0);
Node* loop = graph()->NewNode(common()->Loop(2), start(), start());
Branch b1 = NewBranch(p0, loop);
Branch b2 = NewBranch(p0, b1.if_true);
loop->ReplaceInput(1, b2.if_true);
Node* merge = graph()->NewNode(common()->Merge(2), b1.if_false, b2.if_false);
InsertReturn(p0, start(), merge);
{
LoopTree* loop_tree = GetLoopTree();
LoopTree::Loop* loop = loop_tree->outer_loops()[0];
EXPECT_FALSE(LoopPeeler::CanPeel(loop_tree, loop));
}
}
const Operator kMockCall(IrOpcode::kCall, Operator::kNoProperties, "MockCall",
0, 0, 1, 1, 0, 2);
TEST_F(LoopPeelingTest, TwoExitLoopWithCall_nope) {
Node* p0 = Parameter(0);
Node* loop = graph()->NewNode(common()->Loop(2), start(), start());
Branch b1 = NewBranch(p0, loop);
Node* call = graph()->NewNode(&kMockCall, b1.if_true);
Node* if_success = graph()->NewNode(common()->IfSuccess(), call);
Node* if_exception = graph()->NewNode(common()->IfException(), call);
loop->ReplaceInput(1, if_success);
Node* merge = graph()->NewNode(common()->Merge(2), b1.if_false, if_exception);
InsertReturn(p0, start(), merge);
{
LoopTree* loop_tree = GetLoopTree();
LoopTree::Loop* loop = loop_tree->outer_loops()[0];
EXPECT_FALSE(LoopPeeler::CanPeel(loop_tree, loop));
}
}
} // namespace compiler
} // namespace internal
} // namespace v8
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