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//===- BasicBlockUtils.cpp - Unit tests for BasicBlockUtils ---------------===//
//
// 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/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Analysis/BlockFrequencyInfo.h"
#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/PostDominators.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"
using namespace llvm;
static std::unique_ptr<Module> parseIR(LLVMContext &C, const char *IR) {
SMDiagnostic Err;
std::unique_ptr<Module> Mod = parseAssemblyString(IR, Err, C);
if (!Mod)
Err.print("BasicBlockUtilsTests", errs());
return Mod;
}
TEST(BasicBlockUtils, EliminateUnreachableBlocks) {
LLVMContext C;
std::unique_ptr<Module> M = parseIR(
C,
"define i32 @has_unreachable(i1 %cond) {\n"
"entry:\n"
" br i1 %cond, label %bb0, label %bb1\n"
"bb0:\n"
" br label %bb1\n"
"bb1:\n"
" %phi = phi i32 [ 0, %entry ], [ 1, %bb0 ]"
" ret i32 %phi\n"
"bb2:\n"
" ret i32 42\n"
"}\n"
"\n"
);
auto *F = M->getFunction("has_unreachable");
DominatorTree DT(*F);
DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
EXPECT_EQ(F->size(), (size_t)4);
bool Result = EliminateUnreachableBlocks(*F, &DTU);
EXPECT_TRUE(Result);
EXPECT_EQ(F->size(), (size_t)3);
EXPECT_TRUE(DT.verify());
}
TEST(BasicBlockUtils, NoUnreachableBlocksToEliminate) {
LLVMContext C;
std::unique_ptr<Module> M = parseIR(
C,
"define i32 @no_unreachable(i1 %cond) {\n"
"entry:\n"
" br i1 %cond, label %bb0, label %bb1\n"
"bb0:\n"
" br label %bb1\n"
"bb1:\n"
" %phi = phi i32 [ 0, %entry ], [ 1, %bb0 ]"
" ret i32 %phi\n"
"}\n"
"\n"
);
auto *F = M->getFunction("no_unreachable");
DominatorTree DT(*F);
DomTreeUpdater DTU(DT, DomTreeUpdater::UpdateStrategy::Eager);
EXPECT_EQ(F->size(), (size_t)3);
bool Result = EliminateUnreachableBlocks(*F, &DTU);
EXPECT_FALSE(Result);
EXPECT_EQ(F->size(), (size_t)3);
EXPECT_TRUE(DT.verify());
}
TEST(BasicBlockUtils, SplitBlockPredecessors) {
LLVMContext C;
std::unique_ptr<Module> M = parseIR(
C,
"define i32 @basic_func(i1 %cond) {\n"
"entry:\n"
" br i1 %cond, label %bb0, label %bb1\n"
"bb0:\n"
" br label %bb1\n"
"bb1:\n"
" %phi = phi i32 [ 0, %entry ], [ 1, %bb0 ]"
" ret i32 %phi\n"
"}\n"
"\n"
);
auto *F = M->getFunction("basic_func");
DominatorTree DT(*F);
// Make sure the dominator tree is properly updated if calling this on the
// entry block.
SplitBlockPredecessors(&F->getEntryBlock(), {}, "split.entry", &DT);
EXPECT_TRUE(DT.verify());
}
TEST(BasicBlockUtils, SplitCriticalEdge) {
LLVMContext C;
std::unique_ptr<Module> M = parseIR(
C,
"define void @crit_edge(i1 %cond0, i1 %cond1) {\n"
"entry:\n"
" br i1 %cond0, label %bb0, label %bb1\n"
"bb0:\n"
" br label %bb1\n"
"bb1:\n"
" br label %bb2\n"
"bb2:\n"
" ret void\n"
"}\n"
"\n"
);
auto *F = M->getFunction("crit_edge");
DominatorTree DT(*F);
PostDominatorTree PDT(*F);
CriticalEdgeSplittingOptions CESO(&DT, nullptr, nullptr, &PDT);
EXPECT_EQ(1u, SplitAllCriticalEdges(*F, CESO));
EXPECT_TRUE(DT.verify());
EXPECT_TRUE(PDT.verify());
}
TEST(BasicBlockUtils, SplitIndirectBrCriticalEdge) {
LLVMContext C;
std::unique_ptr<Module> M =
parseIR(C, "define void @crit_edge(i8* %cond0, i1 %cond1) {\n"
"entry:\n"
" indirectbr i8* %cond0, [label %bb0, label %bb1]\n"
"bb0:\n"
" br label %bb1\n"
"bb1:\n"
" %p = phi i32 [0, %bb0], [0, %entry]\n"
" br i1 %cond1, label %bb2, label %bb3\n"
"bb2:\n"
" ret void\n"
"bb3:\n"
" ret void\n"
"}\n");
auto *F = M->getFunction("crit_edge");
DominatorTree DT(*F);
LoopInfo LI(DT);
BranchProbabilityInfo BPI(*F, LI);
BlockFrequencyInfo BFI(*F, BPI, LI);
auto Block = [&F](StringRef BBName) -> const BasicBlock & {
for (auto &BB : *F)
if (BB.getName() == BBName)
return BB;
llvm_unreachable("Block not found");
};
bool Split = SplitIndirectBrCriticalEdges(*F, &BPI, &BFI);
EXPECT_TRUE(Split);
// Check that successors of the split block get their probability correct.
BasicBlock *SplitBB = Block("bb1").getTerminator()->getSuccessor(0);
EXPECT_EQ(2u, SplitBB->getTerminator()->getNumSuccessors());
EXPECT_EQ(BranchProbability(1, 2), BPI.getEdgeProbability(SplitBB, 0u));
EXPECT_EQ(BranchProbability(1, 2), BPI.getEdgeProbability(SplitBB, 1u));
}
TEST(BasicBlockUtils, SetEdgeProbability) {
LLVMContext C;
std::unique_ptr<Module> M = parseIR(
C, "define void @edge_probability(i32 %0) {\n"
"entry:\n"
"switch i32 %0, label %LD [\n"
" i32 700, label %L0\n"
" i32 701, label %L1\n"
" i32 702, label %L2\n"
" i32 703, label %L3\n"
" i32 704, label %L4\n"
" i32 705, label %L5\n"
" i32 706, label %L6\n"
" i32 707, label %L7\n"
" i32 708, label %L8\n"
" i32 709, label %L9\n"
" i32 710, label %L10\n"
" i32 711, label %L11\n"
" i32 712, label %L12\n"
" i32 713, label %L13\n"
" i32 714, label %L14\n"
" i32 715, label %L15\n"
" i32 716, label %L16\n"
" i32 717, label %L17\n"
" i32 718, label %L18\n"
" i32 719, label %L19\n"
"], !prof !{!\"branch_weights\", i32 1, i32 1, i32 1, i32 1, i32 1, "
"i32 451, i32 1, i32 12, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, "
"i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1}\n"
"LD:\n"
" unreachable\n"
"L0:\n"
" ret void\n"
"L1:\n"
" ret void\n"
"L2:\n"
" ret void\n"
"L3:\n"
" ret void\n"
"L4:\n"
" ret void\n"
"L5:\n"
" ret void\n"
"L6:\n"
" ret void\n"
"L7:\n"
" ret void\n"
"L8:\n"
" ret void\n"
"L9:\n"
" ret void\n"
"L10:\n"
" ret void\n"
"L11:\n"
" ret void\n"
"L12:\n"
" ret void\n"
"L13:\n"
" ret void\n"
"L14:\n"
" ret void\n"
"L15:\n"
" ret void\n"
"L16:\n"
" ret void\n"
"L17:\n"
" ret void\n"
"L18:\n"
" ret void\n"
"L19:\n"
" ret void\n"
"}\n");
auto *F = M->getFunction("edge_probability");
DominatorTree DT(*F);
LoopInfo LI(DT);
BranchProbabilityInfo BPI(*F, LI);
auto Block = [&F](StringRef BBName) -> const BasicBlock & {
for (auto &BB : *F)
if (BB.getName() == BBName)
return BB;
llvm_unreachable("Block not found");
};
// Check that the unreachable block has the minimal probability.
const BasicBlock &EntryBB = Block("entry");
const BasicBlock &UnreachableBB = Block("LD");
EXPECT_EQ(BranchProbability::getRaw(1),
BPI.getEdgeProbability(&EntryBB, &UnreachableBB));
}
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