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Revert "[BPI] Use a safer constructor to calculate branch probabilities"

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This reverts commit r290016. It breaks this bot, even though the test
passes locally:

  http://bb.pgr.jp/builders/ninja-x64-msvc-RA-centos6/builds/32956/

AnalysisTests: /home/bb/ninja-x64-msvc-RA-centos6/llvm-project/llvm/lib/Support/BranchProbability.cpp:52: static llvm::BranchProbability llvm::BranchProbability::getBranchProbability(uint64_t, uint64_t): Assertion `Numerator <= Denominator && "Probability cannot be bigger than 1!"' failed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@290019 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Vedant Kumar 2016-12-17 00:19:06 +00:00
parent 48d47ae3d9
commit a908bbaf8d
3 changed files with 12 additions and 101 deletions
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24
lib/Analysis/BranchProbabilityInfo.cpp
View File

@ -162,12 +162,12 @@ bool BranchProbabilityInfo::calcUnreachableHeuristics(const BasicBlock *BB) {
return true;
}
auto UnreachableProb = BranchProbability::getBranchProbability(
UR_TAKEN_WEIGHT,
(UR_TAKEN_WEIGHT + UR_NONTAKEN_WEIGHT) * UnreachableEdges.size());
auto ReachableProb = BranchProbability::getBranchProbability(
UR_NONTAKEN_WEIGHT,
(UR_TAKEN_WEIGHT + UR_NONTAKEN_WEIGHT) * ReachableEdges.size());
BranchProbability UnreachableProb(UR_TAKEN_WEIGHT,
(UR_TAKEN_WEIGHT + UR_NONTAKEN_WEIGHT) *
UnreachableEdges.size());
BranchProbability ReachableProb(UR_NONTAKEN_WEIGHT,
(UR_TAKEN_WEIGHT + UR_NONTAKEN_WEIGHT) *
ReachableEdges.size());
for (unsigned SuccIdx : UnreachableEdges)
setEdgeProbability(BB, SuccIdx, UnreachableProb);
@ -300,12 +300,12 @@ bool BranchProbabilityInfo::calcColdCallHeuristics(const BasicBlock *BB) {
return true;
}
auto ColdProb = BranchProbability::getBranchProbability(
CC_TAKEN_WEIGHT,
(CC_TAKEN_WEIGHT + CC_NONTAKEN_WEIGHT) * ColdEdges.size());
auto NormalProb = BranchProbability::getBranchProbability(
CC_NONTAKEN_WEIGHT,
(CC_TAKEN_WEIGHT + CC_NONTAKEN_WEIGHT) * NormalEdges.size());
BranchProbability ColdProb(CC_TAKEN_WEIGHT,
(CC_TAKEN_WEIGHT + CC_NONTAKEN_WEIGHT) *
ColdEdges.size());
BranchProbability NormalProb(CC_NONTAKEN_WEIGHT,
(CC_TAKEN_WEIGHT + CC_NONTAKEN_WEIGHT) *
NormalEdges.size());
for (unsigned SuccIdx : ColdEdges)
setEdgeProbability(BB, SuccIdx, ColdProb);

88
unittests/Analysis/BranchProbabilityInfoTest.cpp
View File

@ -1,88 +0,0 @@
//===- BranchProbabilityInfoTest.cpp - BranchProbabilityInfo unit tests ---===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/BranchProbabilityInfo.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/raw_ostream.h"
#include "gtest/gtest.h"
namespace llvm {
namespace {
struct BranchProbabilityInfoTest : public testing::Test {
std::unique_ptr<BranchProbabilityInfo> BPI;
std::unique_ptr<DominatorTree> DT;
std::unique_ptr<LoopInfo> LI;
LLVMContext C;
BranchProbabilityInfo &buildBPI(Function &F) {
DT.reset(new DominatorTree(F));
LI.reset(new LoopInfo(*DT));
BPI.reset(new BranchProbabilityInfo(F, *LI));
return *BPI;
}
std::unique_ptr<Module> makeLLVMModule() {
const char *ModuleString = "define void @f() { exit: ret void }\n";
SMDiagnostic Err;
return parseAssemblyString(ModuleString, Err, C);
}
};
TEST_F(BranchProbabilityInfoTest, StressUnreachableHeuristic) {
auto M = makeLLVMModule();
Function *F = M->getFunction("f");
// define void @f() {
// entry:
// switch i32 undef, label %exit, [
// i32 0, label %preexit
// ... ;;< Add lots of cases to stress the heuristic.
// ]
// preexit:
// unreachable
// exit:
// ret void
// }
auto *ExitBB = &F->back();
auto *EntryBB = BasicBlock::Create(C, "entry", F, /*insertBefore=*/ExitBB);
auto *PreExitBB =
BasicBlock::Create(C, "preexit", F, /*insertBefore=*/ExitBB);
new UnreachableInst(C, PreExitBB);
unsigned NumCases = 4096;
auto *I32 = IntegerType::get(C, 32);
auto *Undef = UndefValue::get(I32);
auto *Switch = SwitchInst::Create(Undef, ExitBB, NumCases, EntryBB);
for (unsigned I = 0; I < NumCases; ++I)
Switch->addCase(ConstantInt::get(I32, I), PreExitBB);
BranchProbabilityInfo &BPI = buildBPI(*F);
// FIXME: This doesn't seem optimal. Since all of the cases handled by the
// switch have the *same* destination block ("preexit"), shouldn't it be the
// hot one? I'd expect the results to be reversed here...
EXPECT_FALSE(BPI.isEdgeHot(EntryBB, PreExitBB));
EXPECT_TRUE(BPI.isEdgeHot(EntryBB, ExitBB));
}
} // end anonymous namespace
} // end namespace llvm

1
unittests/Analysis/CMakeLists.txt
View File

@ -8,7 +8,6 @@ set(LLVM_LINK_COMPONENTS
add_llvm_unittest(AnalysisTests
AliasAnalysisTest.cpp
BlockFrequencyInfoTest.cpp
BranchProbabilityInfoTest.cpp
CallGraphTest.cpp
CFGTest.cpp
CGSCCPassManagerTest.cpp