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Merge rust-lang#51
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51: Gate our changes to the `.llvmbbaddrmap` section. r=ltratt a=vext01



Co-authored-by: Edd Barrett <vext01@gmail.com>
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@bors @vext01
bors[bot] and vext01 authored Nov 28, 2022
2 parents 42490d3 + c75eec9 commit fb45fc6
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Showing 3 changed files with 137 additions and 136 deletions.
248 changes: 128 additions & 120 deletions llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -134,6 +134,7 @@ static cl::opt<bool>
"optimisations and transformations have run."));

extern bool YkAllocLLVMBBAddrMapSection;
extern bool YkExtendedLLVMBBAddrMapSection;

const char DWARFGroupName[] = "dwarf";
const char DWARFGroupDescription[] = "DWARF Emission";
Expand Down Expand Up @@ -1438,141 +1439,147 @@ void AsmPrinter::emitBBAddrMapSection(const MachineFunction &MF) {
emitLabelDifferenceAsULEB128(MBB.getEndSymbol(), MBBSymbol);
OutStreamer->emitULEB128IntValue(getBBAddrMapMetadata(MBB));
PrevMBBEndSymbol = MBB.getEndSymbol();
// Find BBs corresponding with this MBB as described above.
const BasicBlock *CorrBB = MBB.getBasicBlock();
std::vector<const BasicBlock *> CorrBBs;
while (CorrBB != nullptr) {
CorrBBs.push_back(CorrBB);
const Instruction *Term = CorrBB->getTerminator();
assert(Term != nullptr);
if ((isa<BranchInst>(Term)) &&
(!(dyn_cast<const BranchInst>(Term))->isConditional())) {
CorrBB = CorrBB->getUniqueSuccessor();
assert(CorrBB != nullptr);
if (MergedBBs.count(CorrBB) == 0) {

if (YkExtendedLLVMBBAddrMapSection) {
// Find BBs corresponding with this MBB as described above.
const BasicBlock *CorrBB = MBB.getBasicBlock();
std::vector<const BasicBlock *> CorrBBs;
while (CorrBB != nullptr) {
CorrBBs.push_back(CorrBB);
const Instruction *Term = CorrBB->getTerminator();
assert(Term != nullptr);
if ((isa<BranchInst>(Term)) &&
(!(dyn_cast<const BranchInst>(Term))->isConditional())) {
CorrBB = CorrBB->getUniqueSuccessor();
assert(CorrBB != nullptr);
if (MergedBBs.count(CorrBB) == 0) {
CorrBB = nullptr;
}
} else {
CorrBB = nullptr;
}
} else {
CorrBB = nullptr;
}
}
// Emit the number of corresponding BasicBlocks.
OutStreamer->emitULEB128IntValue(CorrBBs.size());
// Emit the corresponding block indices.
for (auto CorrBB : CorrBBs) {
size_t I = 0;
bool Found = false;
for (auto It = F.begin(); It != F.end(); It++) {
const BasicBlock *BB = &*It;
if (BB == CorrBB) {
Found = true;
break;
// Emit the number of corresponding BasicBlocks.
OutStreamer->emitULEB128IntValue(CorrBBs.size());
// Emit the corresponding block indices.
for (auto CorrBB : CorrBBs) {
size_t I = 0;
bool Found = false;
for (auto It = F.begin(); It != F.end(); It++) {
const BasicBlock *BB = &*It;
if (BB == CorrBB) {
Found = true;
break;
}
I++;
}
I++;
if (!Found)
OutContext.reportError(SMLoc(), "Couldn't find the block's index");
OutStreamer->emitULEB128IntValue(I);
}
if (!Found)
OutContext.reportError(SMLoc(), "Couldn't find the block's index");
OutStreamer->emitULEB128IntValue(I);
}

// Emit call marker table for the Yk JIT.
//
// The table is a size header, followed by call instruction addresses.
//
// YKOPT: to save space, instead of using absolute symbol addresses, compute
// the distance from the start of the block and use uleb128 encoding.
const size_t NumCalls = YkCallMarkerSyms[&MBB].size();
OutStreamer->emitULEB128IntValue(NumCalls);
for (auto Tup : YkCallMarkerSyms[&MBB]) {
// Emit address of the call instruction.
OutStreamer->emitSymbolValue(std::get<0>(Tup), getPointerSize());
// Emit address of target if known, or 0.
MCSymbol *Target = std::get<1>(Tup);
if (Target)
OutStreamer->emitSymbolValue(Target, getPointerSize());
else
OutStreamer->emitIntValue(0, getPointerSize());
}
// Emit call marker table for the Yk JIT.
//
// The table is a size header, followed by call instruction addresses.
//
// YKOPT: to save space, instead of using absolute symbol addresses,
// compute the distance from the start of the block and use uleb128
// encoding.
const size_t NumCalls = YkCallMarkerSyms[&MBB].size();
OutStreamer->emitULEB128IntValue(NumCalls);
for (auto Tup : YkCallMarkerSyms[&MBB]) {
// Emit address of the call instruction.
OutStreamer->emitSymbolValue(std::get<0>(Tup), getPointerSize());
// Emit address of target if known, or 0.
MCSymbol *Target = std::get<1>(Tup);
if (Target)
OutStreamer->emitSymbolValue(Target, getPointerSize());
else
OutStreamer->emitIntValue(0, getPointerSize());
}

// Emit successor information.
//
// Each codegenned block gets a record indicating any statically known
// successors. The record starts with a `SuccessorKind` byte:
enum SuccessorKind {
// One successor.
Unconditional = 0,
// Choice of two successors.
Conditional = 1,
// A control flow edge known only at runtime, e.g. a return or an indirect
// branch.
Dynamic = 2,
};

// Then depending of the `SuccessorKind` there is a payload describing the
// successors:
//
// `Unconditional`: [target-address: u64]
// `Conditional`: [taken-address: u64, not-taken-address: u64]
// `Dynamic`: [] (i.e. nothing, because nothing is statically known)

MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
SmallVector<MachineOperand> Conds;

if (!TI->analyzeBranch(const_cast<MachineBasicBlock &>(MBB), TBB, FBB,
Conds)) {
// The block ends with a branch or a fall-thru.
if (!TBB && !FBB) {
// Both null: block has no terminator and either falls through or
// diverges.
OutStreamer->emitInt8(Unconditional);
MachineBasicBlock *ThruBB = findFallthruBlock(&MBB);
if (ThruBB) {
OutStreamer->emitSymbolValue(BBSym(ThruBB, FunctionSymbol),
getPointerSize());
} else {
OutStreamer->emitInt64(0); // Divergent.
}
} else if (TBB && !FBB) {
// Only FBB null: block either ends with an unconditional branch or a
// conditional branch whose false arm falls through or diverges.
if (Conds.empty()) {
// No conditions: unconditional branch.
// Emit successor information.
//
// Each codegenned block gets a record indicating any statically known
// successors. The record starts with a `SuccessorKind` byte:
enum SuccessorKind {
// One successor.
Unconditional = 0,
// Choice of two successors.
Conditional = 1,
// A control flow edge known only at runtime, e.g. a return or an
// indirect
// branch.
Dynamic = 2,
};

// Then depending of the `SuccessorKind` there is a payload describing the
// successors:
//
// `Unconditional`: [target-address: u64]
// `Conditional`: [taken-address: u64, not-taken-address: u64]
// `Dynamic`: [] (i.e. nothing, because nothing is statically known)

MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
SmallVector<MachineOperand> Conds;

if (!TI->analyzeBranch(const_cast<MachineBasicBlock &>(MBB), TBB, FBB,
Conds)) {
// The block ends with a branch or a fall-thru.
if (!TBB && !FBB) {
// Both null: block has no terminator and either falls through or
// diverges.
OutStreamer->emitInt8(Unconditional);
OutStreamer->emitSymbolValue(BBSym(TBB, FunctionSymbol),
getPointerSize());
} else {
// Has conditions: conditional branch followed by fallthru or
// divergence.
MachineBasicBlock *ThruBB = findFallthruBlock(&MBB);
OutStreamer->emitInt8(Conditional);
OutStreamer->emitSymbolValue(BBSym(TBB, FunctionSymbol),
getPointerSize());
if (ThruBB) {
OutStreamer->emitSymbolValue(BBSym(ThruBB, FunctionSymbol),
getPointerSize());
} else {
OutStreamer->emitInt64(0); // Divergent.
}
} else if (TBB && !FBB) {
// Only FBB null: block either ends with an unconditional branch or a
// conditional branch whose false arm falls through or diverges.
if (Conds.empty()) {
// No conditions: unconditional branch.
OutStreamer->emitInt8(Unconditional);
OutStreamer->emitSymbolValue(BBSym(TBB, FunctionSymbol),
getPointerSize());
} else {
// Has conditions: conditional branch followed by fallthru or
// divergence.
MachineBasicBlock *ThruBB = findFallthruBlock(&MBB);
OutStreamer->emitInt8(Conditional);
OutStreamer->emitSymbolValue(BBSym(TBB, FunctionSymbol),
getPointerSize());
if (ThruBB) {
OutStreamer->emitSymbolValue(BBSym(ThruBB, FunctionSymbol),
getPointerSize());
} else {
OutStreamer->emitInt64(0); // Divergent.
}
}
} else {
// Conditional branch followed by an unconditional branch.
assert(TBB && FBB);
OutStreamer->emitInt8(Conditional);
OutStreamer->emitSymbolValue(BBSym(TBB, FunctionSymbol),
getPointerSize());
OutStreamer->emitSymbolValue(BBSym(FBB, FunctionSymbol),
getPointerSize());
}
} else {
// Conditional branch followed by an unconditional branch.
assert(TBB && FBB);
OutStreamer->emitInt8(Conditional);
OutStreamer->emitSymbolValue(BBSym(TBB, FunctionSymbol),
getPointerSize());
OutStreamer->emitSymbolValue(BBSym(FBB, FunctionSymbol),
getPointerSize());
}
} else {
// Wasn't a branch or a fall-thru. Must be a different kind of terminator.
const MachineInstr *LastI = &*MBB.instr_rbegin();
if (LastI->isReturn() || LastI->isIndirectBranch()) {
OutStreamer->emitInt8(Dynamic);
} else {
std::string Msg = "unhandled block terminator in block: ";
raw_string_ostream OS(Msg);
LastI->print(OS);
OutContext.reportError(SMLoc(), Msg);
// Wasn't a branch or a fall-thru. Must be a different kind of
// terminator.
const MachineInstr *LastI = &*MBB.instr_rbegin();
if (LastI->isReturn() || LastI->isIndirectBranch()) {
OutStreamer->emitInt8(Dynamic);
} else {
std::string Msg = "unhandled block terminator in block: ";
raw_string_ostream OS(Msg);
LastI->print(OS);
OutContext.reportError(SMLoc(), Msg);
}
}
}
}
Expand Down Expand Up @@ -1697,7 +1704,8 @@ void AsmPrinter::emitFunctionBody() {
// Print a label for the basic block.
emitBasicBlockStart(MBB);

YkCallMarkerSyms.insert({&MBB, {}});
if (YkExtendedLLVMBBAddrMapSection)
YkCallMarkerSyms.insert({&MBB, {}});

DenseMap<StringRef, unsigned> MnemonicCounts;
for (auto &MI : MBB) {
Expand Down Expand Up @@ -1774,7 +1782,7 @@ void AsmPrinter::emitFunctionBody() {
break;
default:

if (YkAllocLLVMBBAddrMapSection && MI.isCall() &&
if (YkExtendedLLVMBBAddrMapSection && MI.isCall() &&
(MI.getOpcode() != TargetOpcode::STACKMAP) &&
(MI.getOpcode() != TargetOpcode::PATCHPOINT) &&
(MI.getOpcode() != TargetOpcode::STATEPOINT)) {
Expand Down
6 changes: 6 additions & 0 deletions llvm/lib/Support/Yk.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12,3 +12,9 @@ static cl::opt<bool, true> YkAllocLLVMBBAddrMapSectionParser(
"yk-alloc-llvmbbaddrmap-section",
cl::desc("Make the `.llvmbbaddrmap` section loadable"), cl::NotHidden,
cl::location(YkAllocLLVMBBAddrMapSection));

bool YkExtendedLLVMBBAddrMapSection;
static cl::opt<bool, true> YkExtendedLLVMBBAddrMapSectionParser(
"yk-extended-llvmbbaddrmap-section",
cl::desc("Use the extended Yk `.llvmbbaddrmap` section format"),
cl::NotHidden, cl::location(YkExtendedLLVMBBAddrMapSection));
19 changes: 3 additions & 16 deletions llvm/test/CodeGen/X86/basic-block-sections-labels.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -53,25 +53,12 @@ declare i32 @__gxx_personality_v0(...)
; CHECK-NEXT: .uleb128 .Lfunc_begin0-.Lfunc_begin0
; CHECK-NEXT: .uleb128 .LBB_END0_0-.Lfunc_begin0
; CHECK-NEXT: .byte 8
; CHECK-NEXT: .byte 1
; CHECK-NEXT: .byte 0
; ...calls and successor info for Yk JIT...
; CHECK: .uleb128 .LBB0_1-.LBB_END0_0
; CHECK-NEXT: .uleb128 .LBB0_1-.LBB_END0_0
; CHECK-NEXT: .uleb128 .LBB_END0_1-.LBB0_1
; CHECK-NEXT: .byte 8
; CHECK-NEXT: .byte 1
; CHECK-NEXT: .byte 1
; ...calls and successor info for Yk JIT...
; CHECK: .uleb128 .LBB0_2-.LBB_END0_1
; CHECK-NEXT: .uleb128 .LBB0_2-.LBB_END0_1
; CHECK-NEXT: .uleb128 .LBB_END0_2-.LBB0_2
; CHECK-NEXT: .byte 1
; CHECK-NEXT: .byte 2
; CHECK-NEXT: .byte 3
; CHECK-NEXT: .byte 4
; ...calls and successor info for Yk JIT...
; CHECK: .uleb128 .LBB0_3-.LBB_END0_2
; CHECK-NEXT: .uleb128 .LBB0_3-.LBB_END0_2
; CHECK-NEXT: .uleb128 .LBB_END0_3-.LBB0_3
; CHECK-NEXT: .byte 5
; CHECK-NEXT: .byte 2
; CHECK-NEXT: .byte 2
; CHECK-NEXT: .byte 4

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