You've already forked linux-packaging-mono
Imported Upstream version 5.18.0.234
Former-commit-id: 8071ec1a8c5eaa9be24b41745add19297608001f
This commit is contained in:
Xamarin Public Jenkins (auto-signing)
parent
f32dbaf0b2
commit
212f6bafcb
@ -1,296 +0,0 @@
|
||||
//===- SimplifyCFGPass.cpp - CFG Simplification Pass ----------------------===//
|
||||
//
|
||||
// The LLVM Compiler Infrastructure
|
||||
//
|
||||
// This file is distributed under the University of Illinois Open Source
|
||||
// License. See LICENSE.TXT for details.
|
||||
//
|
||||
//===----------------------------------------------------------------------===//
|
||||
//
|
||||
// This file implements dead code elimination and basic block merging, along
|
||||
// with a collection of other peephole control flow optimizations. For example:
|
||||
//
|
||||
// * Removes basic blocks with no predecessors.
|
||||
// * Merges a basic block into its predecessor if there is only one and the
|
||||
// predecessor only has one successor.
|
||||
// * Eliminates PHI nodes for basic blocks with a single predecessor.
|
||||
// * Eliminates a basic block that only contains an unconditional branch.
|
||||
// * Changes invoke instructions to nounwind functions to be calls.
|
||||
// * Change things like "if (x) if (y)" into "if (x&y)".
|
||||
// * etc..
|
||||
//
|
||||
//===----------------------------------------------------------------------===//
|
||||
|
||||
#include "llvm/ADT/SmallPtrSet.h"
|
||||
#include "llvm/ADT/SmallVector.h"
|
||||
#include "llvm/ADT/Statistic.h"
|
||||
#include "llvm/Analysis/AssumptionCache.h"
|
||||
#include "llvm/Analysis/CFG.h"
|
||||
#include "llvm/Analysis/GlobalsModRef.h"
|
||||
#include "llvm/Analysis/TargetTransformInfo.h"
|
||||
#include "llvm/IR/Attributes.h"
|
||||
#include "llvm/IR/CFG.h"
|
||||
#include "llvm/IR/Constants.h"
|
||||
#include "llvm/IR/DataLayout.h"
|
||||
#include "llvm/IR/Instructions.h"
|
||||
#include "llvm/IR/IntrinsicInst.h"
|
||||
#include "llvm/IR/Module.h"
|
||||
#include "llvm/Pass.h"
|
||||
#include "llvm/Support/CommandLine.h"
|
||||
#include "llvm/Transforms/Scalar.h"
|
||||
#include "llvm/Transforms/Scalar/SimplifyCFG.h"
|
||||
#include "llvm/Transforms/Utils/Local.h"
|
||||
#include <utility>
|
||||
using namespace llvm;
|
||||
|
||||
#define DEBUG_TYPE "simplifycfg"
|
||||
|
||||
static cl::opt<unsigned> UserBonusInstThreshold(
|
||||
"bonus-inst-threshold", cl::Hidden, cl::init(1),
|
||||
cl::desc("Control the number of bonus instructions (default = 1)"));
|
||||
|
||||
static cl::opt<bool> UserKeepLoops(
|
||||
"keep-loops", cl::Hidden, cl::init(true),
|
||||
cl::desc("Preserve canonical loop structure (default = true)"));
|
||||
|
||||
static cl::opt<bool> UserSwitchToLookup(
|
||||
"switch-to-lookup", cl::Hidden, cl::init(false),
|
||||
cl::desc("Convert switches to lookup tables (default = false)"));
|
||||
|
||||
static cl::opt<bool> UserForwardSwitchCond(
|
||||
"forward-switch-cond", cl::Hidden, cl::init(false),
|
||||
cl::desc("Forward switch condition to phi ops (default = false)"));
|
||||
|
||||
static cl::opt<bool> UserSinkCommonInsts(
|
||||
"sink-common-insts", cl::Hidden, cl::init(false),
|
||||
cl::desc("Sink common instructions (default = false)"));
|
||||
|
||||
|
||||
STATISTIC(NumSimpl, "Number of blocks simplified");
|
||||
|
||||
/// If we have more than one empty (other than phi node) return blocks,
|
||||
/// merge them together to promote recursive block merging.
|
||||
static bool mergeEmptyReturnBlocks(Function &F) {
|
||||
bool Changed = false;
|
||||
|
||||
BasicBlock *RetBlock = nullptr;
|
||||
|
||||
// Scan all the blocks in the function, looking for empty return blocks.
|
||||
for (Function::iterator BBI = F.begin(), E = F.end(); BBI != E; ) {
|
||||
BasicBlock &BB = *BBI++;
|
||||
|
||||
// Only look at return blocks.
|
||||
ReturnInst *Ret = dyn_cast<ReturnInst>(BB.getTerminator());
|
||||
if (!Ret) continue;
|
||||
|
||||
// Only look at the block if it is empty or the only other thing in it is a
|
||||
// single PHI node that is the operand to the return.
|
||||
if (Ret != &BB.front()) {
|
||||
// Check for something else in the block.
|
||||
BasicBlock::iterator I(Ret);
|
||||
--I;
|
||||
// Skip over debug info.
|
||||
while (isa<DbgInfoIntrinsic>(I) && I != BB.begin())
|
||||
--I;
|
||||
if (!isa<DbgInfoIntrinsic>(I) &&
|
||||
(!isa<PHINode>(I) || I != BB.begin() || Ret->getNumOperands() == 0 ||
|
||||
Ret->getOperand(0) != &*I))
|
||||
continue;
|
||||
}
|
||||
|
||||
// If this is the first returning block, remember it and keep going.
|
||||
if (!RetBlock) {
|
||||
RetBlock = &BB;
|
||||
continue;
|
||||
}
|
||||
|
||||
// Otherwise, we found a duplicate return block. Merge the two.
|
||||
Changed = true;
|
||||
|
||||
// Case when there is no input to the return or when the returned values
|
||||
// agree is trivial. Note that they can't agree if there are phis in the
|
||||
// blocks.
|
||||
if (Ret->getNumOperands() == 0 ||
|
||||
Ret->getOperand(0) ==
|
||||
cast<ReturnInst>(RetBlock->getTerminator())->getOperand(0)) {
|
||||
BB.replaceAllUsesWith(RetBlock);
|
||||
BB.eraseFromParent();
|
||||
continue;
|
||||
}
|
||||
|
||||
// If the canonical return block has no PHI node, create one now.
|
||||
PHINode *RetBlockPHI = dyn_cast<PHINode>(RetBlock->begin());
|
||||
if (!RetBlockPHI) {
|
||||
Value *InVal = cast<ReturnInst>(RetBlock->getTerminator())->getOperand(0);
|
||||
pred_iterator PB = pred_begin(RetBlock), PE = pred_end(RetBlock);
|
||||
RetBlockPHI = PHINode::Create(Ret->getOperand(0)->getType(),
|
||||
std::distance(PB, PE), "merge",
|
||||
&RetBlock->front());
|
||||
|
||||
for (pred_iterator PI = PB; PI != PE; ++PI)
|
||||
RetBlockPHI->addIncoming(InVal, *PI);
|
||||
RetBlock->getTerminator()->setOperand(0, RetBlockPHI);
|
||||
}
|
||||
|
||||
// Turn BB into a block that just unconditionally branches to the return
|
||||
// block. This handles the case when the two return blocks have a common
|
||||
// predecessor but that return different things.
|
||||
RetBlockPHI->addIncoming(Ret->getOperand(0), &BB);
|
||||
BB.getTerminator()->eraseFromParent();
|
||||
BranchInst::Create(RetBlock, &BB);
|
||||
}
|
||||
|
||||
return Changed;
|
||||
}
|
||||
|
||||
/// Call SimplifyCFG on all the blocks in the function,
|
||||
/// iterating until no more changes are made.
|
||||
static bool iterativelySimplifyCFG(Function &F, const TargetTransformInfo &TTI,
|
||||
const SimplifyCFGOptions &Options) {
|
||||
bool Changed = false;
|
||||
bool LocalChange = true;
|
||||
|
||||
SmallVector<std::pair<const BasicBlock *, const BasicBlock *>, 32> Edges;
|
||||
FindFunctionBackedges(F, Edges);
|
||||
SmallPtrSet<BasicBlock *, 16> LoopHeaders;
|
||||
for (unsigned i = 0, e = Edges.size(); i != e; ++i)
|
||||
LoopHeaders.insert(const_cast<BasicBlock *>(Edges[i].second));
|
||||
|
||||
while (LocalChange) {
|
||||
LocalChange = false;
|
||||
|
||||
// Loop over all of the basic blocks and remove them if they are unneeded.
|
||||
for (Function::iterator BBIt = F.begin(); BBIt != F.end(); ) {
|
||||
if (simplifyCFG(&*BBIt++, TTI, Options, &LoopHeaders)) {
|
||||
LocalChange = true;
|
||||
++NumSimpl;
|
||||
}
|
||||
}
|
||||
Changed |= LocalChange;
|
||||
}
|
||||
return Changed;
|
||||
}
|
||||
|
||||
static bool simplifyFunctionCFG(Function &F, const TargetTransformInfo &TTI,
|
||||
const SimplifyCFGOptions &Options) {
|
||||
bool EverChanged = removeUnreachableBlocks(F);
|
||||
EverChanged |= mergeEmptyReturnBlocks(F);
|
||||
EverChanged |= iterativelySimplifyCFG(F, TTI, Options);
|
||||
|
||||
// If neither pass changed anything, we're done.
|
||||
if (!EverChanged) return false;
|
||||
|
||||
// iterativelySimplifyCFG can (rarely) make some loops dead. If this happens,
|
||||
// removeUnreachableBlocks is needed to nuke them, which means we should
|
||||
// iterate between the two optimizations. We structure the code like this to
|
||||
// avoid rerunning iterativelySimplifyCFG if the second pass of
|
||||
// removeUnreachableBlocks doesn't do anything.
|
||||
if (!removeUnreachableBlocks(F))
|
||||
return true;
|
||||
|
||||
do {
|
||||
EverChanged = iterativelySimplifyCFG(F, TTI, Options);
|
||||
EverChanged |= removeUnreachableBlocks(F);
|
||||
} while (EverChanged);
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
// Command-line settings override compile-time settings.
|
||||
SimplifyCFGPass::SimplifyCFGPass(const SimplifyCFGOptions &Opts) {
|
||||
Options.BonusInstThreshold = UserBonusInstThreshold.getNumOccurrences()
|
||||
? UserBonusInstThreshold
|
||||
: Opts.BonusInstThreshold;
|
||||
Options.ForwardSwitchCondToPhi = UserForwardSwitchCond.getNumOccurrences()
|
||||
? UserForwardSwitchCond
|
||||
: Opts.ForwardSwitchCondToPhi;
|
||||
Options.ConvertSwitchToLookupTable = UserSwitchToLookup.getNumOccurrences()
|
||||
? UserSwitchToLookup
|
||||
: Opts.ConvertSwitchToLookupTable;
|
||||
Options.NeedCanonicalLoop = UserKeepLoops.getNumOccurrences()
|
||||
? UserKeepLoops
|
||||
: Opts.NeedCanonicalLoop;
|
||||
Options.SinkCommonInsts = UserSinkCommonInsts.getNumOccurrences()
|
||||
? UserSinkCommonInsts
|
||||
: Opts.SinkCommonInsts;
|
||||
}
|
||||
|
||||
PreservedAnalyses SimplifyCFGPass::run(Function &F,
|
||||
FunctionAnalysisManager &AM) {
|
||||
auto &TTI = AM.getResult<TargetIRAnalysis>(F);
|
||||
Options.AC = &AM.getResult<AssumptionAnalysis>(F);
|
||||
if (!simplifyFunctionCFG(F, TTI, Options))
|
||||
return PreservedAnalyses::all();
|
||||
PreservedAnalyses PA;
|
||||
PA.preserve<GlobalsAA>();
|
||||
return PA;
|
||||
}
|
||||
|
||||
namespace {
|
||||
struct CFGSimplifyPass : public FunctionPass {
|
||||
static char ID;
|
||||
SimplifyCFGOptions Options;
|
||||
std::function<bool(const Function &)> PredicateFtor;
|
||||
|
||||
CFGSimplifyPass(unsigned Threshold = 1, bool ForwardSwitchCond = false,
|
||||
bool ConvertSwitch = false, bool KeepLoops = true,
|
||||
bool SinkCommon = false,
|
||||
std::function<bool(const Function &)> Ftor = nullptr)
|
||||
: FunctionPass(ID), PredicateFtor(std::move(Ftor)) {
|
||||
|
||||
initializeCFGSimplifyPassPass(*PassRegistry::getPassRegistry());
|
||||
|
||||
// Check for command-line overrides of options for debug/customization.
|
||||
Options.BonusInstThreshold = UserBonusInstThreshold.getNumOccurrences()
|
||||
? UserBonusInstThreshold
|
||||
: Threshold;
|
||||
|
||||
Options.ForwardSwitchCondToPhi = UserForwardSwitchCond.getNumOccurrences()
|
||||
? UserForwardSwitchCond
|
||||
: ForwardSwitchCond;
|
||||
|
||||
Options.ConvertSwitchToLookupTable = UserSwitchToLookup.getNumOccurrences()
|
||||
? UserSwitchToLookup
|
||||
: ConvertSwitch;
|
||||
|
||||
Options.NeedCanonicalLoop =
|
||||
UserKeepLoops.getNumOccurrences() ? UserKeepLoops : KeepLoops;
|
||||
|
||||
Options.SinkCommonInsts = UserSinkCommonInsts.getNumOccurrences()
|
||||
? UserSinkCommonInsts
|
||||
: SinkCommon;
|
||||
}
|
||||
|
||||
bool runOnFunction(Function &F) override {
|
||||
if (skipFunction(F) || (PredicateFtor && !PredicateFtor(F)))
|
||||
return false;
|
||||
|
||||
Options.AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
|
||||
auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
|
||||
return simplifyFunctionCFG(F, TTI, Options);
|
||||
}
|
||||
void getAnalysisUsage(AnalysisUsage &AU) const override {
|
||||
AU.addRequired<AssumptionCacheTracker>();
|
||||
AU.addRequired<TargetTransformInfoWrapperPass>();
|
||||
AU.addPreserved<GlobalsAAWrapperPass>();
|
||||
}
|
||||
};
|
||||
}
|
||||
|
||||
char CFGSimplifyPass::ID = 0;
|
||||
INITIALIZE_PASS_BEGIN(CFGSimplifyPass, "simplifycfg", "Simplify the CFG", false,
|
||||
false)
|
||||
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
|
||||
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
|
||||
INITIALIZE_PASS_END(CFGSimplifyPass, "simplifycfg", "Simplify the CFG", false,
|
||||
false)
|
||||
|
||||
// Public interface to the CFGSimplification pass
|
||||
FunctionPass *
|
||||
llvm::createCFGSimplificationPass(unsigned Threshold, bool ForwardSwitchCond,
|
||||
bool ConvertSwitch, bool KeepLoops,
|
||||
bool SinkCommon,
|
||||
std::function<bool(const Function &)> Ftor) {
|
||||
return new CFGSimplifyPass(Threshold, ForwardSwitchCond, ConvertSwitch,
|
||||
KeepLoops, SinkCommon, std::move(Ftor));
|
||||
}
|
||||
Reference in New Issue
Block a user