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CodeGen: factor out swifterror value tracking.

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llvm-svn: 361607
This commit is contained in:
Tim Northover 2019-05-24 08:39:43 +00:00
parent c559c55ff2
commit fefb8f4f37
9 changed files with 457 additions and 383 deletions
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42
include/llvm/CodeGen/FunctionLoweringInfo.h
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@ -71,48 +71,6 @@ public:
/// MBBMap - A mapping from LLVM basic blocks to their machine code entry.
DenseMap<const BasicBlock*, MachineBasicBlock *> MBBMap;
/// A map from swifterror value in a basic block to the virtual register it is
/// currently represented by.
DenseMap<std::pair<const MachineBasicBlock *, const Value *>, unsigned>
SwiftErrorVRegDefMap;
/// A list of upward exposed vreg uses that need to be satisfied by either a
/// copy def or a phi node at the beginning of the basic block representing
/// the predecessor(s) swifterror value.
DenseMap<std::pair<const MachineBasicBlock *, const Value *>, unsigned>
SwiftErrorVRegUpwardsUse;
/// A map from instructions that define/use a swifterror value to the virtual
/// register that represents that def/use.
llvm::DenseMap<PointerIntPair<const Instruction *, 1, bool>, unsigned>
SwiftErrorVRegDefUses;
/// The swifterror argument of the current function.
const Value *SwiftErrorArg;
using SwiftErrorValues = SmallVector<const Value*, 1>;
/// A function can only have a single swifterror argument. And if it does
/// have a swifterror argument, it must be the first entry in
/// SwiftErrorVals.
SwiftErrorValues SwiftErrorVals;
/// Get or create the swifterror value virtual register in
/// SwiftErrorVRegDefMap for this basic block.
unsigned getOrCreateSwiftErrorVReg(const MachineBasicBlock *,
const Value *);
/// Set the swifterror virtual register in the SwiftErrorVRegDefMap for this
/// basic block.
void setCurrentSwiftErrorVReg(const MachineBasicBlock *MBB, const Value *,
unsigned);
/// Get or create the swifterror value virtual register for a def of a
/// swifterror by an instruction.
std::pair<unsigned, bool> getOrCreateSwiftErrorVRegDefAt(const Instruction *);
std::pair<unsigned, bool>
getOrCreateSwiftErrorVRegUseAt(const Instruction *, const MachineBasicBlock *,
const Value *);
/// ValueMap - Since we emit code for the function a basic block at a time,
/// we must remember which virtual registers hold the values for
/// cross-basic-block values.

2
include/llvm/CodeGen/SelectionDAGISel.h
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@ -34,6 +34,7 @@ namespace llvm {
class TargetLibraryInfo;
class FunctionLoweringInfo;
class ScheduleHazardRecognizer;
class SwiftErrorValueTracking;
class GCFunctionInfo;
class ScheduleDAGSDNodes;
class LoadInst;
@ -45,6 +46,7 @@ public:
TargetMachine &TM;
const TargetLibraryInfo *LibInfo;
FunctionLoweringInfo *FuncInfo;
SwiftErrorValueTracking *SwiftError;
MachineFunction *MF;
MachineRegisterInfo *RegInfo;
SelectionDAG *CurDAG;

109
include/llvm/CodeGen/SwiftErrorValueTracking.h Normal file
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@ -0,0 +1,109 @@
//===- SwiftErrorValueTracking.h - Track swifterror VReg vals --*- C++ -*--===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This implements a limited mem2reg-like analysis to promote uses of function
// arguments and allocas marked with swiftalloc from memory into virtual
// registers tracked by this class.
//
//===----------------------------------------------------------------------===//
#ifndef SWIFTERRORVALUETRACKING_H
#define SWIFTERRORVALUETRACKING_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/DebugLoc.h"
#include <functional>
#include <type_traits>
#include <utility>
namespace llvm {
class Function;
class MachineBasicBlock;
class MachineFunction;
class MachineInstr;
class TargetInstrInfo;
class TargetLowering;
class SwiftErrorValueTracking {
// Some useful objects to reduce the number of function arguments needed.
MachineFunction *MF;
const Function *Fn;
const TargetLowering *TLI;
const TargetInstrInfo *TII;
/// A map from swifterror value in a basic block to the virtual register it is
/// currently represented by.
DenseMap<std::pair<const MachineBasicBlock *, const Value *>, unsigned>
VRegDefMap;
/// A list of upward exposed vreg uses that need to be satisfied by either a
/// copy def or a phi node at the beginning of the basic block representing
/// the predecessor(s) swifterror value.
DenseMap<std::pair<const MachineBasicBlock *, const Value *>, unsigned>
VRegUpwardsUse;
/// A map from instructions that define/use a swifterror value to the virtual
/// register that represents that def/use.
llvm::DenseMap<PointerIntPair<const Instruction *, 1, bool>, unsigned>
VRegDefUses;
/// The swifterror argument of the current function.
const Value *SwiftErrorArg;
using SwiftErrorValues = SmallVector<const Value*, 1>;
/// A function can only have a single swifterror argument. And if it does
/// have a swifterror argument, it must be the first entry in
/// SwiftErrorVals.
SwiftErrorValues SwiftErrorVals;
public:
/// Initialize data structures for specified new function.
void setFunction(MachineFunction &MF);
/// Get the (unique) function argument that was marked swifterror, or nullptr
/// if this function has no swifterror args.
const Value *getFunctionArg() const {
return SwiftErrorArg;
}
/// Get or create the swifterror value virtual register in
/// VRegDefMap for this basic block.
unsigned getOrCreateVReg(const MachineBasicBlock *, const Value *);
/// Set the swifterror virtual register in the VRegDefMap for this
/// basic block.
void setCurrentVReg(const MachineBasicBlock *MBB, const Value *, unsigned);
/// Get or create the swifterror value virtual register for a def of a
/// swifterror by an instruction.
unsigned getOrCreateVRegDefAt(const Instruction *, const MachineBasicBlock *,
const Value *);
/// Get or create the swifterror value virtual register for a use of a
/// swifterror by an instruction.
unsigned getOrCreateVRegUseAt(const Instruction *, const MachineBasicBlock *,
const Value *);
/// Create initial definitions of swifterror values in the entry block of the
/// current function.
bool createEntriesInEntryBlock(DebugLoc DbgLoc);
/// Propagate assigned swifterror vregs through a function, synthesizing PHI
/// nodes when needed to maintain consistency.
void propagateVRegs();
void preassignVRegs(MachineBasicBlock *MBB, BasicBlock::const_iterator Begin,
BasicBlock::const_iterator End);
};
}
#endif

1
lib/CodeGen/CMakeLists.txt
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@ -143,6 +143,7 @@ add_llvm_library(LLVMCodeGen
StackMaps.cpp
StackProtector.cpp
StackSlotColoring.cpp
SwiftErrorValueTracking.cpp
TailDuplication.cpp
TailDuplicator.cpp
TargetFrameLoweringImpl.cpp

50
lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
View File

@ -519,56 +519,6 @@ unsigned FunctionLoweringInfo::getCatchPadExceptionPointerVReg(
return VReg;
}
unsigned
FunctionLoweringInfo::getOrCreateSwiftErrorVReg(const MachineBasicBlock *MBB,
const Value *Val) {
auto Key = std::make_pair(MBB, Val);
auto It = SwiftErrorVRegDefMap.find(Key);
// If this is the first use of this swifterror value in this basic block,
// create a new virtual register.
// After we processed all basic blocks we will satisfy this "upwards exposed
// use" by inserting a copy or phi at the beginning of this block.
if (It == SwiftErrorVRegDefMap.end()) {
auto &DL = MF->getDataLayout();
const TargetRegisterClass *RC = TLI->getRegClassFor(TLI->getPointerTy(DL));
auto VReg = MF->getRegInfo().createVirtualRegister(RC);
SwiftErrorVRegDefMap[Key] = VReg;
SwiftErrorVRegUpwardsUse[Key] = VReg;
return VReg;
} else return It->second;
}
void FunctionLoweringInfo::setCurrentSwiftErrorVReg(
const MachineBasicBlock *MBB, const Value *Val, unsigned VReg) {
SwiftErrorVRegDefMap[std::make_pair(MBB, Val)] = VReg;
}
std::pair<unsigned, bool>
FunctionLoweringInfo::getOrCreateSwiftErrorVRegDefAt(const Instruction *I) {
auto Key = PointerIntPair<const Instruction *, 1, bool>(I, true);
auto It = SwiftErrorVRegDefUses.find(Key);
if (It == SwiftErrorVRegDefUses.end()) {
auto &DL = MF->getDataLayout();
const TargetRegisterClass *RC = TLI->getRegClassFor(TLI->getPointerTy(DL));
unsigned VReg = MF->getRegInfo().createVirtualRegister(RC);
SwiftErrorVRegDefUses[Key] = VReg;
return std::make_pair(VReg, true);
}
return std::make_pair(It->second, false);
}
std::pair<unsigned, bool>
FunctionLoweringInfo::getOrCreateSwiftErrorVRegUseAt(const Instruction *I, const MachineBasicBlock *MBB, const Value *Val) {
auto Key = PointerIntPair<const Instruction *, 1, bool>(I, false);
auto It = SwiftErrorVRegDefUses.find(Key);
if (It == SwiftErrorVRegDefUses.end()) {
unsigned VReg = getOrCreateSwiftErrorVReg(MBB, Val);
SwiftErrorVRegDefUses[Key] = VReg;
return std::make_pair(VReg, true);
}
return std::make_pair(It->second, false);
}
const Value *
FunctionLoweringInfo::getValueFromVirtualReg(unsigned Vreg) {
if (VirtReg2Value.empty()) {

36
lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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@ -54,6 +54,7 @@
#include "llvm/CodeGen/SelectionDAGNodes.h"
#include "llvm/CodeGen/SelectionDAGTargetInfo.h"
#include "llvm/CodeGen/StackMaps.h"
#include "llvm/CodeGen/SwiftErrorValueTracking.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
@ -1895,7 +1896,7 @@ void SelectionDAGBuilder::visitRet(const ReturnInst &I) {
const Function *F = I.getParent()->getParent();
if (TLI.supportSwiftError() &&
F->getAttributes().hasAttrSomewhere(Attribute::SwiftError)) {
assert(FuncInfo.SwiftErrorArg && "Need a swift error argument");
assert(SwiftError.getFunctionArg() && "Need a swift error argument");
ISD::ArgFlagsTy Flags = ISD::ArgFlagsTy();
Flags.setSwiftError();
Outs.push_back(ISD::OutputArg(Flags, EVT(TLI.getPointerTy(DL)) /*vt*/,
@ -1904,8 +1905,8 @@ void SelectionDAGBuilder::visitRet(const ReturnInst &I) {
0 /*partOffs*/));
// Create SDNode for the swifterror virtual register.
OutVals.push_back(
DAG.getRegister(FuncInfo.getOrCreateSwiftErrorVRegUseAt(
&I, FuncInfo.MBB, FuncInfo.SwiftErrorArg).first,
DAG.getRegister(SwiftError.getOrCreateVRegUseAt(
&I, FuncInfo.MBB, SwiftError.getFunctionArg()),
EVT(TLI.getPointerTy(DL))));
}
@ -4146,15 +4147,13 @@ void SelectionDAGBuilder::visitStoreToSwiftError(const StoreInst &I) {
SDValue Src = getValue(SrcV);
// Create a virtual register, then update the virtual register.
unsigned VReg; bool CreatedVReg;
std::tie(VReg, CreatedVReg) = FuncInfo.getOrCreateSwiftErrorVRegDefAt(&I);
unsigned VReg =
SwiftError.getOrCreateVRegDefAt(&I, FuncInfo.MBB, I.getPointerOperand());
// Chain, DL, Reg, N or Chain, DL, Reg, N, Glue
// Chain can be getRoot or getControlRoot.
SDValue CopyNode = DAG.getCopyToReg(getRoot(), getCurSDLoc(), VReg,
SDValue(Src.getNode(), Src.getResNo()));
DAG.setRoot(CopyNode);
if (CreatedVReg)
FuncInfo.setCurrentSwiftErrorVReg(FuncInfo.MBB, I.getOperand(1), VReg);
}
void SelectionDAGBuilder::visitLoadFromSwiftError(const LoadInst &I) {
@ -4187,8 +4186,7 @@ void SelectionDAGBuilder::visitLoadFromSwiftError(const LoadInst &I) {
// Chain, DL, Reg, VT, Glue or Chain, DL, Reg, VT
SDValue L = DAG.getCopyFromReg(
getRoot(), getCurSDLoc(),
FuncInfo.getOrCreateSwiftErrorVRegUseAt(&I, FuncInfo.MBB, SV).first,
ValueVTs[0]);
SwiftError.getOrCreateVRegUseAt(&I, FuncInfo.MBB, SV), ValueVTs[0]);
setValue(&I, L);
}
@ -7073,11 +7071,9 @@ void SelectionDAGBuilder::LowerCallTo(ImmutableCallSite CS, SDValue Callee,
SwiftErrorVal = V;
// We find the virtual register for the actual swifterror argument.
// Instead of using the Value, we use the virtual register instead.
Entry.Node = DAG.getRegister(FuncInfo
.getOrCreateSwiftErrorVRegUseAt(
CS.getInstruction(), FuncInfo.MBB, V)
.first,
EVT(TLI.getPointerTy(DL)));
Entry.Node = DAG.getRegister(
SwiftError.getOrCreateVRegUseAt(CS.getInstruction(), FuncInfo.MBB, V),
EVT(TLI.getPointerTy(DL)));
}
Args.push_back(Entry);
@ -7118,13 +7114,9 @@ void SelectionDAGBuilder::LowerCallTo(ImmutableCallSite CS, SDValue Callee,
if (SwiftErrorVal && TLI.supportSwiftError()) {
// Get the last element of InVals.
SDValue Src = CLI.InVals.back();
unsigned VReg; bool CreatedVReg;
std::tie(VReg, CreatedVReg) =
FuncInfo.getOrCreateSwiftErrorVRegDefAt(CS.getInstruction());
unsigned VReg = SwiftError.getOrCreateVRegDefAt(
CS.getInstruction(), FuncInfo.MBB, SwiftErrorVal);
SDValue CopyNode = CLI.DAG.getCopyToReg(Result.second, CLI.DL, VReg, Src);
// We update the virtual register for the actual swifterror argument.
if (CreatedVReg)
FuncInfo.setCurrentSwiftErrorVReg(FuncInfo.MBB, SwiftErrorVal, VReg);
DAG.setRoot(CopyNode);
}
}
@ -9761,8 +9753,8 @@ void SelectionDAGISel::LowerArguments(const Function &F) {
if (Res.getOpcode() == ISD::CopyFromReg && isSwiftErrorArg) {
unsigned Reg = cast<RegisterSDNode>(Res.getOperand(1))->getReg();
if (TargetRegisterInfo::isVirtualRegister(Reg))
FuncInfo->setCurrentSwiftErrorVReg(FuncInfo->MBB,
FuncInfo->SwiftErrorArg, Reg);
SwiftError->setCurrentVReg(FuncInfo->MBB, SwiftError->getFunctionArg(),
Reg);
}
// If this argument is live outside of the entry block, insert a copy from

10
lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
View File

@ -77,6 +77,7 @@ class ResumeInst;
class ReturnInst;
class SDDbgValue;
class StoreInst;
class SwiftErrorValueTracking;
class SwitchInst;
class TargetLibraryInfo;
class TargetMachine;
@ -613,6 +614,9 @@ public:
/// Information about the function as a whole.
FunctionLoweringInfo &FuncInfo;
/// Information about the swifterror values used throughout the function.
SwiftErrorValueTracking &SwiftError;
/// Garbage collection metadata for the function.
GCFunctionInfo *GFI;
@ -626,9 +630,9 @@ public:
LLVMContext *Context;
SelectionDAGBuilder(SelectionDAG &dag, FunctionLoweringInfo &funcinfo,
CodeGenOpt::Level ol)
: SDNodeOrder(LowestSDNodeOrder), TM(dag.getTarget()), DAG(dag),
FuncInfo(funcinfo) {}
SwiftErrorValueTracking &swifterror, CodeGenOpt::Level ol)
: SDNodeOrder(LowestSDNodeOrder), TM(dag.getTarget()), DAG(dag),
FuncInfo(funcinfo), SwiftError(swifterror) {}
void init(GCFunctionInfo *gfi, AliasAnalysis *AA,
const TargetLibraryInfo *li);

278
lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
View File

@ -49,6 +49,7 @@
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SelectionDAGNodes.h"
#include "llvm/CodeGen/StackProtector.h"
#include "llvm/CodeGen/SwiftErrorValueTracking.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
@ -307,8 +308,9 @@ SelectionDAGISel::SelectionDAGISel(TargetMachine &tm,
CodeGenOpt::Level OL) :
MachineFunctionPass(ID), TM(tm),
FuncInfo(new FunctionLoweringInfo()),
SwiftError(new SwiftErrorValueTracking()),
CurDAG(new SelectionDAG(tm, OL)),
SDB(new SelectionDAGBuilder(*CurDAG, *FuncInfo, OL)),
SDB(new SelectionDAGBuilder(*CurDAG, *FuncInfo, *SwiftError, OL)),
AA(), GFI(),
OptLevel(OL),
DAGSize(0) {
@ -324,6 +326,7 @@ SelectionDAGISel::~SelectionDAGISel() {
delete SDB;
delete CurDAG;
delete FuncInfo;
delete SwiftError;
}
void SelectionDAGISel::getAnalysisUsage(AnalysisUsage &AU) const {
@ -446,6 +449,7 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
CurDAG->init(*MF, *ORE, this, LibInfo,
getAnalysisIfAvailable<LegacyDivergenceAnalysis>());
FuncInfo->set(Fn, *MF, CurDAG);
SwiftError->setFunction(*MF);
// Now get the optional analyzes if we want to.
// This is based on the possibly changed OptLevel (after optnone is taken
@ -1254,77 +1258,6 @@ static bool isFoldedOrDeadInstruction(const Instruction *I,
!FuncInfo->isExportedInst(I); // Exported instrs must be computed.
}
/// Set up SwiftErrorVals by going through the function. If the function has
/// swifterror argument, it will be the first entry.
static void setupSwiftErrorVals(const Function &Fn, const TargetLowering *TLI,
FunctionLoweringInfo *FuncInfo) {
if (!TLI->supportSwiftError())
return;
FuncInfo->SwiftErrorVals.clear();
FuncInfo->SwiftErrorVRegDefMap.clear();
FuncInfo->SwiftErrorVRegUpwardsUse.clear();
FuncInfo->SwiftErrorVRegDefUses.clear();
FuncInfo->SwiftErrorArg = nullptr;
// Check if function has a swifterror argument.
bool HaveSeenSwiftErrorArg = false;
for (Function::const_arg_iterator AI = Fn.arg_begin(), AE = Fn.arg_end();
AI != AE; ++AI)
if (AI->hasSwiftErrorAttr()) {
assert(!HaveSeenSwiftErrorArg &&
"Must have only one swifterror parameter");
(void)HaveSeenSwiftErrorArg; // silence warning.
HaveSeenSwiftErrorArg = true;
FuncInfo->SwiftErrorArg = &*AI;
FuncInfo->SwiftErrorVals.push_back(&*AI);
}
for (const auto &LLVMBB : Fn)
for (const auto &Inst : LLVMBB) {
if (const AllocaInst *Alloca = dyn_cast<AllocaInst>(&Inst))
if (Alloca->isSwiftError())
FuncInfo->SwiftErrorVals.push_back(Alloca);
}
}
static void createSwiftErrorEntriesInEntryBlock(FunctionLoweringInfo *FuncInfo,
FastISel *FastIS,
const TargetLowering *TLI,
const TargetInstrInfo *TII,
SelectionDAGBuilder *SDB) {
if (!TLI->supportSwiftError())
return;
// We only need to do this when we have swifterror parameter or swifterror
// alloc.
if (FuncInfo->SwiftErrorVals.empty())
return;
assert(FuncInfo->MBB == &*FuncInfo->MF->begin() &&
"expected to insert into entry block");
auto &DL = FuncInfo->MF->getDataLayout();
auto const *RC = TLI->getRegClassFor(TLI->getPointerTy(DL));
for (const auto *SwiftErrorVal : FuncInfo->SwiftErrorVals) {
// We will always generate a copy from the argument. It is always used at
// least by the 'return' of the swifterror.
if (FuncInfo->SwiftErrorArg && FuncInfo->SwiftErrorArg == SwiftErrorVal)
continue;
unsigned VReg = FuncInfo->MF->getRegInfo().createVirtualRegister(RC);
// Assign Undef to Vreg. We construct MI directly to make sure it works
// with FastISel.
BuildMI(*FuncInfo->MBB, FuncInfo->MBB->getFirstNonPHI(),
SDB->getCurDebugLoc(), TII->get(TargetOpcode::IMPLICIT_DEF),
VReg);
// Keep FastIS informed about the value we just inserted.
if (FastIS)
FastIS->setLastLocalValue(&*std::prev(FuncInfo->InsertPt));
FuncInfo->setCurrentSwiftErrorVReg(FuncInfo->MBB, SwiftErrorVal, VReg);
}
}
/// Collect llvm.dbg.declare information. This is done after argument lowering
/// in case the declarations refer to arguments.
static void processDbgDeclares(FunctionLoweringInfo *FuncInfo) {
@ -1370,195 +1303,6 @@ static void processDbgDeclares(FunctionLoweringInfo *FuncInfo) {
}
}
/// Propagate swifterror values through the machine function CFG.
static void propagateSwiftErrorVRegs(FunctionLoweringInfo *FuncInfo) {
auto *TLI = FuncInfo->TLI;
if (!TLI->supportSwiftError())
return;
// We only need to do this when we have swifterror parameter or swifterror
// alloc.
if (FuncInfo->SwiftErrorVals.empty())
return;
// For each machine basic block in reverse post order.
ReversePostOrderTraversal<MachineFunction *> RPOT(FuncInfo->MF);
for (MachineBasicBlock *MBB : RPOT) {
// For each swifterror value in the function.
for(const auto *SwiftErrorVal : FuncInfo->SwiftErrorVals) {
auto Key = std::make_pair(MBB, SwiftErrorVal);
auto UUseIt = FuncInfo->SwiftErrorVRegUpwardsUse.find(Key);
auto VRegDefIt = FuncInfo->SwiftErrorVRegDefMap.find(Key);
bool UpwardsUse = UUseIt != FuncInfo->SwiftErrorVRegUpwardsUse.end();
unsigned UUseVReg = UpwardsUse ? UUseIt->second : 0;
bool DownwardDef = VRegDefIt != FuncInfo->SwiftErrorVRegDefMap.end();
assert(!(UpwardsUse && !DownwardDef) &&
"We can't have an upwards use but no downwards def");
// If there is no upwards exposed use and an entry for the swifterror in
// the def map for this value we don't need to do anything: We already
// have a downward def for this basic block.
if (!UpwardsUse && DownwardDef)
continue;
// Otherwise we either have an upwards exposed use vreg that we need to
// materialize or need to forward the downward def from predecessors.
// Check whether we have a single vreg def from all predecessors.
// Otherwise we need a phi.
SmallVector<std::pair<MachineBasicBlock *, unsigned>, 4> VRegs;
SmallSet<const MachineBasicBlock*, 8> Visited;
for (auto *Pred : MBB->predecessors()) {
if (!Visited.insert(Pred).second)
continue;
VRegs.push_back(std::make_pair(
Pred, FuncInfo->getOrCreateSwiftErrorVReg(Pred, SwiftErrorVal)));
if (Pred != MBB)
continue;
// We have a self-edge.
// If there was no upwards use in this basic block there is now one: the
// phi needs to use it self.
if (!UpwardsUse) {
UpwardsUse = true;
UUseIt = FuncInfo->SwiftErrorVRegUpwardsUse.find(Key);
assert(UUseIt != FuncInfo->SwiftErrorVRegUpwardsUse.end());
UUseVReg = UUseIt->second;
}
}
// We need a phi node if we have more than one predecessor with different
// downward defs.
bool needPHI =
VRegs.size() >= 1 &&
std::find_if(
VRegs.begin(), VRegs.end(),
[&](const std::pair<const MachineBasicBlock *, unsigned> &V)
-> bool { return V.second != VRegs[0].second; }) !=
VRegs.end();
// If there is no upwards exposed used and we don't need a phi just
// forward the swifterror vreg from the predecessor(s).
if (!UpwardsUse && !needPHI) {
assert(!VRegs.empty() &&
"No predecessors? The entry block should bail out earlier");
// Just forward the swifterror vreg from the predecessor(s).
FuncInfo->setCurrentSwiftErrorVReg(MBB, SwiftErrorVal, VRegs[0].second);
continue;
}
auto DLoc = isa<Instruction>(SwiftErrorVal)
? cast<Instruction>(SwiftErrorVal)->getDebugLoc()
: DebugLoc();
const auto *TII = FuncInfo->MF->getSubtarget().getInstrInfo();
// If we don't need a phi create a copy to the upward exposed vreg.
if (!needPHI) {
assert(UpwardsUse);
assert(!VRegs.empty() &&
"No predecessors? Is the Calling Convention correct?");
unsigned DestReg = UUseVReg;
BuildMI(*MBB, MBB->getFirstNonPHI(), DLoc, TII->get(TargetOpcode::COPY),
DestReg)
.addReg(VRegs[0].second);
continue;
}
// We need a phi: if there is an upwards exposed use we already have a
// destination virtual register number otherwise we generate a new one.
auto &DL = FuncInfo->MF->getDataLayout();
auto const *RC = TLI->getRegClassFor(TLI->getPointerTy(DL));
unsigned PHIVReg =
UpwardsUse ? UUseVReg
: FuncInfo->MF->getRegInfo().createVirtualRegister(RC);
MachineInstrBuilder SwiftErrorPHI =
BuildMI(*MBB, MBB->getFirstNonPHI(), DLoc,
TII->get(TargetOpcode::PHI), PHIVReg);
for (auto BBRegPair : VRegs) {
SwiftErrorPHI.addReg(BBRegPair.second).addMBB(BBRegPair.first);
}
// We did not have a definition in this block before: store the phi's vreg
// as this block downward exposed def.
if (!UpwardsUse)
FuncInfo->setCurrentSwiftErrorVReg(MBB, SwiftErrorVal, PHIVReg);
}
}
}
static void preassignSwiftErrorRegs(const TargetLowering *TLI,
FunctionLoweringInfo *FuncInfo,
BasicBlock::const_iterator Begin,
BasicBlock::const_iterator End) {
if (!TLI->supportSwiftError() || FuncInfo->SwiftErrorVals.empty())
return;
// Iterator over instructions and assign vregs to swifterror defs and uses.
for (auto It = Begin; It != End; ++It) {
ImmutableCallSite CS(&*It);
if (CS) {
// A call-site with a swifterror argument is both use and def.
const Value *SwiftErrorAddr = nullptr;
for (auto &Arg : CS.args()) {
if (!Arg->isSwiftError())
continue;
// Use of swifterror.
assert(!SwiftErrorAddr && "Cannot have multiple swifterror arguments");
SwiftErrorAddr = &*Arg;
assert(SwiftErrorAddr->isSwiftError() &&
"Must have a swifterror value argument");
unsigned VReg; bool CreatedReg;
std::tie(VReg, CreatedReg) = FuncInfo->getOrCreateSwiftErrorVRegUseAt(
&*It, FuncInfo->MBB, SwiftErrorAddr);
assert(CreatedReg);
}
if (!SwiftErrorAddr)
continue;
// Def of swifterror.
unsigned VReg; bool CreatedReg;
std::tie(VReg, CreatedReg) =
FuncInfo->getOrCreateSwiftErrorVRegDefAt(&*It);
assert(CreatedReg);
FuncInfo->setCurrentSwiftErrorVReg(FuncInfo->MBB, SwiftErrorAddr, VReg);
// A load is a use.
} else if (const LoadInst *LI = dyn_cast<const LoadInst>(&*It)) {
const Value *V = LI->getOperand(0);
if (!V->isSwiftError())
continue;
unsigned VReg; bool CreatedReg;
std::tie(VReg, CreatedReg) =
FuncInfo->getOrCreateSwiftErrorVRegUseAt(LI, FuncInfo->MBB, V);
assert(CreatedReg);
// A store is a def.
} else if (const StoreInst *SI = dyn_cast<const StoreInst>(&*It)) {
const Value *SwiftErrorAddr = SI->getOperand(1);
if (!SwiftErrorAddr->isSwiftError())
continue;
// Def of swifterror.
unsigned VReg; bool CreatedReg;
std::tie(VReg, CreatedReg) =
FuncInfo->getOrCreateSwiftErrorVRegDefAt(&*It);
assert(CreatedReg);
FuncInfo->setCurrentSwiftErrorVReg(FuncInfo->MBB, SwiftErrorAddr, VReg);
// A return in a swiferror returning function is a use.
} else if (const ReturnInst *R = dyn_cast<const ReturnInst>(&*It)) {
const Function *F = R->getParent()->getParent();
if(!F->getAttributes().hasAttrSomewhere(Attribute::SwiftError))
continue;
unsigned VReg; bool CreatedReg;
std::tie(VReg, CreatedReg) = FuncInfo->getOrCreateSwiftErrorVRegUseAt(
R, FuncInfo->MBB, FuncInfo->SwiftErrorArg);
assert(CreatedReg);
}
}
}
void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
FastISelFailed = false;
// Initialize the Fast-ISel state, if needed.
@ -1568,8 +1312,6 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
FastIS = TLI->createFastISel(*FuncInfo, LibInfo);
}
setupSwiftErrorVals(Fn, TLI, FuncInfo);
ReversePostOrderTraversal<const Function*> RPOT(&Fn);
// Lower arguments up front. An RPO iteration always visits the entry block
@ -1615,7 +1357,11 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
else
FastIS->setLastLocalValue(nullptr);
}
createSwiftErrorEntriesInEntryBlock(FuncInfo, FastIS, TLI, TII, SDB);
bool Inserted = SwiftError->createEntriesInEntryBlock(SDB->getCurDebugLoc());
if (FastIS && Inserted)
FastIS->setLastLocalValue(&*std::prev(FuncInfo->InsertPt));
processDbgDeclares(FuncInfo);
@ -1670,7 +1416,7 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
unsigned NumFastIselRemaining = std::distance(Begin, End);
// Pre-assign swifterror vregs.
preassignSwiftErrorRegs(TLI, FuncInfo, Begin, End);
SwiftError->preassignVRegs(FuncInfo->MBB, Begin, End);
// Do FastISel on as many instructions as possible.
for (; BI != Begin; --BI) {
@ -1826,7 +1572,7 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
SP.copyToMachineFrameInfo(MF->getFrameInfo());
propagateSwiftErrorVRegs(FuncInfo);
SwiftError->propagateVRegs();
delete FastIS;
SDB->clearDanglingDebugInfo();

312
lib/CodeGen/SwiftErrorValueTracking.cpp Normal file
View File

@ -0,0 +1,312 @@
//===-- SwiftErrorValueTracking.cpp --------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This implements a limited mem2reg-like analysis to promote uses of function
// arguments and allocas marked with swiftalloc from memory into virtual
// registers tracked by this class.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/SwiftErrorValueTracking.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/IR/Value.h"
using namespace llvm;
unsigned SwiftErrorValueTracking::getOrCreateVReg(const MachineBasicBlock *MBB,
const Value *Val) {
auto Key = std::make_pair(MBB, Val);
auto It = VRegDefMap.find(Key);
// If this is the first use of this swifterror value in this basic block,
// create a new virtual register.
// After we processed all basic blocks we will satisfy this "upwards exposed
// use" by inserting a copy or phi at the beginning of this block.
if (It == VRegDefMap.end()) {
auto &DL = MF->getDataLayout();
const TargetRegisterClass *RC = TLI->getRegClassFor(TLI->getPointerTy(DL));
auto VReg = MF->getRegInfo().createVirtualRegister(RC);
VRegDefMap[Key] = VReg;
VRegUpwardsUse[Key] = VReg;
return VReg;
} else
return It->second;
}
void SwiftErrorValueTracking::setCurrentVReg(const MachineBasicBlock *MBB,
const Value *Val, unsigned VReg) {
VRegDefMap[std::make_pair(MBB, Val)] = VReg;
}
unsigned SwiftErrorValueTracking::getOrCreateVRegDefAt(
const Instruction *I, const MachineBasicBlock *MBB, const Value *Val) {
auto Key = PointerIntPair<const Instruction *, 1, bool>(I, true);
auto It = VRegDefUses.find(Key);
if (It != VRegDefUses.end())
return It->second;
auto &DL = MF->getDataLayout();
const TargetRegisterClass *RC = TLI->getRegClassFor(TLI->getPointerTy(DL));
unsigned VReg = MF->getRegInfo().createVirtualRegister(RC);
VRegDefUses[Key] = VReg;
setCurrentVReg(MBB, Val, VReg);
return VReg;
}
unsigned SwiftErrorValueTracking::getOrCreateVRegUseAt(
const Instruction *I, const MachineBasicBlock *MBB, const Value *Val) {
auto Key = PointerIntPair<const Instruction *, 1, bool>(I, false);
auto It = VRegDefUses.find(Key);
if (It != VRegDefUses.end())
return It->second;
unsigned VReg = getOrCreateVReg(MBB, Val);
VRegDefUses[Key] = VReg;
return VReg;
}
/// Set up SwiftErrorVals by going through the function. If the function has
/// swifterror argument, it will be the first entry.
void SwiftErrorValueTracking::setFunction(MachineFunction &mf) {
MF = &mf;
Fn = &MF->getFunction();
TLI = MF->getSubtarget().getTargetLowering();
TII = MF->getSubtarget().getInstrInfo();
if (!TLI->supportSwiftError())
return;
SwiftErrorVals.clear();
VRegDefMap.clear();
VRegUpwardsUse.clear();
VRegDefUses.clear();
SwiftErrorArg = nullptr;
// Check if function has a swifterror argument.
bool HaveSeenSwiftErrorArg = false;
for (Function::const_arg_iterator AI = Fn->arg_begin(), AE = Fn->arg_end();
AI != AE; ++AI)
if (AI->hasSwiftErrorAttr()) {
assert(!HaveSeenSwiftErrorArg &&
"Must have only one swifterror parameter");
(void)HaveSeenSwiftErrorArg; // silence warning.
HaveSeenSwiftErrorArg = true;
SwiftErrorArg = &*AI;
SwiftErrorVals.push_back(&*AI);
}
for (const auto &LLVMBB : *Fn)
for (const auto &Inst : LLVMBB) {
if (const AllocaInst *Alloca = dyn_cast<AllocaInst>(&Inst))
if (Alloca->isSwiftError())
SwiftErrorVals.push_back(Alloca);
}
}
bool SwiftErrorValueTracking::createEntriesInEntryBlock(DebugLoc DbgLoc) {
if (!TLI->supportSwiftError())
return false;
// We only need to do this when we have swifterror parameter or swifterror
// alloc.
if (SwiftErrorVals.empty())
return false;
MachineBasicBlock *MBB = &*MF->begin();
auto &DL = MF->getDataLayout();
auto const *RC = TLI->getRegClassFor(TLI->getPointerTy(DL));
bool Inserted = false;
for (const auto *SwiftErrorVal : SwiftErrorVals) {
// We will always generate a copy from the argument. It is always used at
// least by the 'return' of the swifterror.
if (SwiftErrorArg && SwiftErrorArg == SwiftErrorVal)
continue;
unsigned VReg = MF->getRegInfo().createVirtualRegister(RC);
// Assign Undef to Vreg. We construct MI directly to make sure it works
// with FastISel.
BuildMI(*MBB, MBB->getFirstNonPHI(), DbgLoc,
TII->get(TargetOpcode::IMPLICIT_DEF), VReg);
setCurrentVReg(MBB, SwiftErrorVal, VReg);
Inserted = true;
}
return Inserted;
}
/// Propagate swifterror values through the machine function CFG.
void SwiftErrorValueTracking::propagateVRegs() {
if (!TLI->supportSwiftError())
return;
// We only need to do this when we have swifterror parameter or swifterror
// alloc.
if (SwiftErrorVals.empty())
return;
// For each machine basic block in reverse post order.
ReversePostOrderTraversal<MachineFunction *> RPOT(MF);
for (MachineBasicBlock *MBB : RPOT) {
// For each swifterror value in the function.
for (const auto *SwiftErrorVal : SwiftErrorVals) {
auto Key = std::make_pair(MBB, SwiftErrorVal);
auto UUseIt = VRegUpwardsUse.find(Key);
auto VRegDefIt = VRegDefMap.find(Key);
bool UpwardsUse = UUseIt != VRegUpwardsUse.end();
unsigned UUseVReg = UpwardsUse ? UUseIt->second : 0;
bool DownwardDef = VRegDefIt != VRegDefMap.end();
assert(!(UpwardsUse && !DownwardDef) &&
"We can't have an upwards use but no downwards def");
// If there is no upwards exposed use and an entry for the swifterror in
// the def map for this value we don't need to do anything: We already
// have a downward def for this basic block.
if (!UpwardsUse && DownwardDef)
continue;
// Otherwise we either have an upwards exposed use vreg that we need to
// materialize or need to forward the downward def from predecessors.
// Check whether we have a single vreg def from all predecessors.
// Otherwise we need a phi.
SmallVector<std::pair<MachineBasicBlock *, unsigned>, 4> VRegs;
SmallSet<const MachineBasicBlock *, 8> Visited;
for (auto *Pred : MBB->predecessors()) {
if (!Visited.insert(Pred).second)
continue;
VRegs.push_back(std::make_pair(
Pred, getOrCreateVReg(Pred, SwiftErrorVal)));
if (Pred != MBB)
continue;
// We have a self-edge.
// If there was no upwards use in this basic block there is now one: the
// phi needs to use it self.
if (!UpwardsUse) {
UpwardsUse = true;
UUseIt = VRegUpwardsUse.find(Key);
assert(UUseIt != VRegUpwardsUse.end());
UUseVReg = UUseIt->second;
}
}
// We need a phi node if we have more than one predecessor with different
// downward defs.
bool needPHI =
VRegs.size() >= 1 &&
std::find_if(
VRegs.begin(), VRegs.end(),
[&](const std::pair<const MachineBasicBlock *, unsigned> &V)
-> bool { return V.second != VRegs[0].second; }) !=
VRegs.end();
// If there is no upwards exposed used and we don't need a phi just
// forward the swifterror vreg from the predecessor(s).
if (!UpwardsUse && !needPHI) {
assert(!VRegs.empty() &&
"No predecessors? The entry block should bail out earlier");
// Just forward the swifterror vreg from the predecessor(s).
setCurrentVReg(MBB, SwiftErrorVal, VRegs[0].second);
continue;
}
auto DLoc = isa<Instruction>(SwiftErrorVal)
? cast<Instruction>(SwiftErrorVal)->getDebugLoc()
: DebugLoc();
const auto *TII = MF->getSubtarget().getInstrInfo();
// If we don't need a phi create a copy to the upward exposed vreg.
if (!needPHI) {
assert(UpwardsUse);
assert(!VRegs.empty() &&
"No predecessors? Is the Calling Convention correct?");
unsigned DestReg = UUseVReg;
BuildMI(*MBB, MBB->getFirstNonPHI(), DLoc, TII->get(TargetOpcode::COPY),
DestReg)
.addReg(VRegs[0].second);
continue;
}
// We need a phi: if there is an upwards exposed use we already have a
// destination virtual register number otherwise we generate a new one.
auto &DL = MF->getDataLayout();
auto const *RC = TLI->getRegClassFor(TLI->getPointerTy(DL));
unsigned PHIVReg =
UpwardsUse ? UUseVReg : MF->getRegInfo().createVirtualRegister(RC);
MachineInstrBuilder PHI =
BuildMI(*MBB, MBB->getFirstNonPHI(), DLoc,
TII->get(TargetOpcode::PHI), PHIVReg);
for (auto BBRegPair : VRegs) {
PHI.addReg(BBRegPair.second).addMBB(BBRegPair.first);
}
// We did not have a definition in this block before: store the phi's vreg
// as this block downward exposed def.
if (!UpwardsUse)
setCurrentVReg(MBB, SwiftErrorVal, PHIVReg);
}
}
}
void SwiftErrorValueTracking::preassignVRegs(
MachineBasicBlock *MBB, BasicBlock::const_iterator Begin,
BasicBlock::const_iterator End) {
if (!TLI->supportSwiftError() || SwiftErrorVals.empty())
return;
// Iterator over instructions and assign vregs to swifterror defs and uses.
for (auto It = Begin; It != End; ++It) {
ImmutableCallSite CS(&*It);
if (CS) {
// A call-site with a swifterror argument is both use and def.
const Value *SwiftErrorAddr = nullptr;
for (auto &Arg : CS.args()) {
if (!Arg->isSwiftError())
continue;
// Use of swifterror.
assert(!SwiftErrorAddr && "Cannot have multiple swifterror arguments");
SwiftErrorAddr = &*Arg;
assert(SwiftErrorAddr->isSwiftError() &&
"Must have a swifterror value argument");
getOrCreateVRegUseAt(&*It, MBB, SwiftErrorAddr);
}
if (!SwiftErrorAddr)
continue;
// Def of swifterror.
getOrCreateVRegDefAt(&*It, MBB, SwiftErrorAddr);
// A load is a use.
} else if (const LoadInst *LI = dyn_cast<const LoadInst>(&*It)) {
const Value *V = LI->getOperand(0);
if (!V->isSwiftError())
continue;
getOrCreateVRegUseAt(LI, MBB, V);
// A store is a def.
} else if (const StoreInst *SI = dyn_cast<const StoreInst>(&*It)) {
const Value *SwiftErrorAddr = SI->getOperand(1);
if (!SwiftErrorAddr->isSwiftError())
continue;
// Def of swifterror.
getOrCreateVRegDefAt(&*It, MBB, SwiftErrorAddr);
// A return in a swiferror returning function is a use.
} else if (const ReturnInst *R = dyn_cast<const ReturnInst>(&*It)) {
const Function *F = R->getParent()->getParent();
if (!F->getAttributes().hasAttrSomewhere(Attribute::SwiftError))
continue;
getOrCreateVRegUseAt(R, MBB, SwiftErrorArg);
}
}
}