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irfunction/ScopeStack: Unify style, add comments (NFC)

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This commit is contained in:
David Nadlinger 2015-08-21 20:42:51 +02:00
parent 6215acc15a
commit d25dee7f89
2 changed files with 134 additions and 78 deletions
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58
ir/irfunction.cpp
View file

@ -17,8 +17,8 @@
#include <sstream>
namespace {
void executeCleanup(IRState *irs, CleanupScope& scope,
llvm::BasicBlock *sourceBlock, llvm::BasicBlock* continueWith
void executeCleanup(IRState* irs, CleanupScope& scope,
llvm::BasicBlock* sourceBlock, llvm::BasicBlock* continueWith
) {
if (scope.exitTargets.empty() || (
scope.exitTargets.size() == 1 &&
@ -59,7 +59,7 @@ void executeCleanup(IRState *irs, CleanupScope& scope,
// And convert the BranchInst to the existing branch target to a
// SelectInst so we can append the other cases to it.
scope.endBlock->getTerminator()->eraseFromParent();
llvm::Value *sel = new llvm::LoadInst(scope.branchSelector, "",
llvm::Value* sel = new llvm::LoadInst(scope.branchSelector, "",
scope.endBlock);
llvm::SwitchInst::Create(
sel,
@ -90,7 +90,7 @@ void executeCleanup(IRState *irs, CleanupScope& scope,
}
// We don't know this branch target yet, so add it to the SwitchInst...
llvm::ConstantInt * const selectorVal = DtoConstUint(scope.exitTargets.size());
llvm::ConstantInt* const selectorVal = DtoConstUint(scope.exitTargets.size());
llvm::cast<llvm::SwitchInst>(scope.endBlock->getTerminator())->addCase(
selectorVal, continueWith);
@ -106,6 +106,9 @@ void executeCleanup(IRState *irs, CleanupScope& scope,
}
ScopeStack::~ScopeStack() {
// If there are still unresolved gotos left, it means that they were either
// down or "sideways" (i.e. down another branch) of the tree of all
// cleanup scopes, both of which are not allowed in D.
if (!topLevelUnresolvedGotos.empty()) {
for (std::vector<GotoJump>::iterator it = topLevelUnresolvedGotos.begin(),
end = topLevelUnresolvedGotos.end();
@ -130,7 +133,7 @@ void ScopeStack::runCleanups(
if (targetScope == sourceScope) {
// No cleanups to run, just branch to the next block.
llvm::BranchInst::Create(continueWith, irs->scopebb());
irs->ir->CreateBr(continueWith);
return;
}
@ -140,7 +143,7 @@ void ScopeStack::runCleanups(
// Update all the control flow in the cleanups to make sure we end up where
// we want.
for (CleanupCursor i = sourceScope; i-- > targetScope;) {
llvm::BasicBlock *nextBlock = (i > targetScope) ?
llvm::BasicBlock* nextBlock = (i > targetScope) ?
cleanupScopes[i - 1].beginBlock : continueWith;
executeCleanup(irs, cleanupScopes[i], irs->scopebb(), nextBlock);
}
@ -151,15 +154,18 @@ void ScopeStack::runAllCleanups(llvm::BasicBlock* continueWith) {
}
void ScopeStack::popCleanups(CleanupCursor targetScope) {
assert(targetScope <= currentCleanupScope());
if (targetScope == currentCleanupScope()) return;
for (CleanupCursor i = currentCleanupScope(); i-- > targetScope;) {
// Any gotos that are still unresolved necessarily leave this scope.
// Thus, the cleanup needs to be executed.
for (std::vector<GotoJump>::iterator it = currentUnresolvedGotos().begin(),
end = currentUnresolvedGotos().end();
it != end; ++it
) {
// Make the source resp. last cleanup branch to this one.
llvm::BasicBlock *tentative = it->tentativeTarget;
llvm::BasicBlock* tentative = it->tentativeTarget;
tentative->replaceAllUsesWith(cleanupScopes[i].beginBlock);
// And continue execution with the tentative target (we simply reuse
@ -219,6 +225,8 @@ void ScopeStack::addLabelTarget(Identifier* labelName,
) {
labelTargets[labelName] = {targetBlock, currentCleanupScope(), 0};
// See whether any of the unresolved gotos target this label, and resolve
// those that do.
std::vector<GotoJump>& unresolved = currentUnresolvedGotos();
size_t i = 0;
while (i < unresolved.size()) {
@ -242,7 +250,7 @@ void ScopeStack::jumpToLabel(Loc loc, Identifier* labelName) {
return;
}
llvm::BasicBlock *target =
llvm::BasicBlock* target =
llvm::BasicBlock::Create(irs->context(), "goto.unresolved", irs->topfunc());
irs->ir->CreateBr(target);
currentUnresolvedGotos().push_back({loc, irs->scopebb(), target, labelName});
@ -283,7 +291,7 @@ std::vector<llvm::BasicBlock*>& ScopeStack::currentLandingPads() {
}
namespace {
llvm::LandingPadInst* createLandingPadInst(IRState *irs) {
llvm::LandingPadInst* createLandingPadInst(IRState* irs) {
LLType* retType = LLStructType::get(LLType::getInt8PtrTy(irs->context()),
LLType::getInt32Ty(irs->context()),
NULL);
@ -305,23 +313,20 @@ llvm::BasicBlock* ScopeStack::emitLandingPad() {
// save and rewrite scope
IRScope savedIRScope = irs->scope();
llvm::BasicBlock *beginBB = llvm::BasicBlock::Create(irs->context(),
llvm::BasicBlock* beginBB = llvm::BasicBlock::Create(irs->context(),
"landingPad", irs->topfunc());
irs->scope() = IRScope(beginBB);
llvm::LandingPadInst *landingPad = createLandingPadInst(irs);
llvm::LandingPadInst* landingPad = createLandingPadInst(irs);
// Stash away the exception object pointer and selector value into their
// stack slots.
llvm::Value* ehPtr = DtoExtractValue(landingPad, 0);
if (!irs->func()->resumeUnwindBlock) {
irs->func()->resumeUnwindBlock = llvm::BasicBlock::Create(
irs->context(),
"unwind.resume",
irs->topfunc()
);
irs->context(), "unwind.resume", irs->topfunc());
llvm::BasicBlock *oldBB = irs->scopebb();
llvm::BasicBlock* oldBB = irs->scopebb();
irs->scope() = IRScope(irs->func()->resumeUnwindBlock);
llvm::Function* resumeFn = LLVM_D_GetRuntimeFunction(Loc(),
@ -364,14 +369,14 @@ llvm::BasicBlock* ScopeStack::emitLandingPad() {
// emitted to the EH tables.
landingPad->addClause(it->classInfoPtr);
llvm::BasicBlock *mismatchBB = llvm::BasicBlock::Create(
llvm::BasicBlock* mismatchBB = llvm::BasicBlock::Create(
irs->context(),
beginBB->getName() + llvm::Twine(".mismatch"),
irs->topfunc()
);
// "Call" llvm.eh.typeid.for, which gives us the eh selector value to compare with
llvm::Value *ehTypeId = irs->ir->CreateCall(GET_INTRINSIC_DECL(eh_typeid_for),
llvm::Value* ehTypeId = irs->ir->CreateCall(GET_INTRINSIC_DECL(eh_typeid_for),
DtoBitCast(it->classInfoPtr, getVoidPtrType()));
// Compare the selector value from the unwinder against the expected
@ -402,8 +407,7 @@ llvm::BasicBlock* ScopeStack::emitLandingPad() {
return beginBB;
}
IrFunction::IrFunction(FuncDeclaration* fd)
{
IrFunction::IrFunction(FuncDeclaration* fd) {
decl = fd;
Type* t = fd->type->toBasetype();
@ -435,8 +439,7 @@ IrFunction::IrFunction(FuncDeclaration* fd)
ehSelectorSlot = NULL;
}
void IrFunction::setNeverInline()
{
void IrFunction::setNeverInline() {
#if LDC_LLVM_VER >= 303
assert(!func->getAttributes().hasAttribute(llvm::AttributeSet::FunctionIndex, llvm::Attribute::AlwaysInline) && "function can't be never- and always-inline at the same time");
func->addFnAttr(llvm::Attribute::NoInline);
@ -449,8 +452,7 @@ void IrFunction::setNeverInline()
#endif
}
void IrFunction::setAlwaysInline()
{
void IrFunction::setAlwaysInline() {
#if LDC_LLVM_VER >= 303
assert(!func->getAttributes().hasAttribute(llvm::AttributeSet::FunctionIndex, llvm::Attribute::NoInline) && "function can't be never- and always-inline at the same time");
func->addFnAttr(llvm::Attribute::AlwaysInline);
@ -470,10 +472,9 @@ llvm::AllocaInst* IrFunction::getOrCreateEhPtrSlot() {
return ehPtrSlot;
}
IrFunction *getIrFunc(FuncDeclaration *decl, bool create)
IrFunction* getIrFunc(FuncDeclaration* decl, bool create)
{
if (!isIrFuncCreated(decl) && create)
{
if (!isIrFuncCreated(decl) && create) {
assert(decl->ir.irFunc == NULL);
decl->ir.irFunc = new IrFunction(decl);
decl->ir.m_type = IrDsymbol::FuncType;
@ -482,8 +483,7 @@ IrFunction *getIrFunc(FuncDeclaration *decl, bool create)
return decl->ir.irFunc;
}
bool isIrFuncCreated(FuncDeclaration *decl)
{
bool isIrFuncCreated(FuncDeclaration* decl) {
int t = decl->ir.type();
assert(t == IrDsymbol::FuncType || t == IrDsymbol::NotSet);
return t == IrDsymbol::FuncType;

154
ir/irfunction.h
View file

@ -7,7 +7,7 @@
//
//===----------------------------------------------------------------------===//
//
// Represents the status of a D function/method/... on its way through the
// Represents the state of a D function/method/... on its way through the
// codegen process.
//
//===----------------------------------------------------------------------===//
@ -31,16 +31,17 @@ class Statement;
/// Represents a position on the stack of currently active cleanup scopes.
///
/// Since we always need to run a contiguous part of the stack (or all) in
/// order, this is enough to uniquely identify the location of a given target.
/// order, two cursors (one of which is usually the currently top of the stack)
/// are enough to identify a sequence of cleanups to run.
typedef size_t CleanupCursor;
/// Stores information needed to correctly jump to a given label or loop
/// statement (break/continue).
/// Stores information needed to correctly jump to a given label or loop/switch
/// statement (break/continue can be labeled, but are not necessarily).
struct JumpTarget {
/// The basic block to ultimately branch to.
llvm::BasicBlock* targetBlock;
/// The index of the label target in the stack of active cleanup scopes.
/// The index of the target in the stack of active cleanup scopes.
///
/// When generating code for a jump to this label, the cleanups between
/// the current depth and that of the level will be emitted. Note that
@ -55,10 +56,12 @@ struct JumpTarget {
Statement* targetStatement;
};
/// Defines source and target label of a goto (used if we cannot immediately
/// figure out the target basic block).
/// Keeps track of source and target label of a goto.
///
/// Used if we cannot immediately emit all the code for a jump because we have
/// not generated code for the target yet.
struct GotoJump {
// The location of the jump instruction, for error reporting.
// The location of the goto instruction, for error reporting.
Loc sourceLoc;
/// The basic block which contains the goto as its terminator.
@ -73,8 +76,11 @@ struct GotoJump {
Identifier* targetLabel;
};
/// Describes a particular way to leave a certain scope and continue execution
/// at another one (return, break/continue, exception handling, etc.).
/// Describes a particular way to leave a cleanup scope and continue execution
/// with another one.
///
/// In general, there can be multiple ones (normal exit, early returns,
/// breaks/continues, exceptions, and so on).
struct CleanupExitTarget {
explicit CleanupExitTarget(llvm::BasicBlock* t) : branchTarget(t) {}
@ -98,7 +104,8 @@ struct CleanupExitTarget {
///
/// Our goal is to only emit each cleanup once such as to avoid generating an
/// exponential number of basic blocks/landing pads for handling all the
/// different ways of exiting a deeply nested scope (exception/no exception/...).
/// different ways of exiting a deeply nested scope (consider e.g. ten
/// local variables with destructors, each of which might throw itself).
class CleanupScope {
public:
CleanupScope(llvm::BasicBlock* beginBlock, llvm::BasicBlock* endBlock) :
@ -107,7 +114,7 @@ public:
/// The basic block to branch to for running the cleanup.
llvm::BasicBlock* beginBlock;
/// The basic block that contains the end of the cleanuip code (is different
/// The basic block that contains the end of the cleanup code (is different
/// from beginBlock if the cleanup contains control flow).
llvm::BasicBlock* endBlock;
@ -117,20 +124,30 @@ public:
/// Stores all possible targets blocks after running this cleanup, along
/// with what predecessors want to continue at that target. The index in
/// the vector corresponds to the branch selector value for that target.
// Note: This is of course a bad choice of data structure for many targets
// complexity-wise. However, situations where this matters should be
// exceedingly rare in both hand-written as well as generated code.
std::vector<CleanupExitTarget> exitTargets;
/// Keeps track of all the gotos somewhere inside this scope for which we
/// have not found the label yet (because it occurs lexically later in the
/// function).
/// Keeps track of all the gotos originating from somewhere inside this
/// scope for which we have not found the label yet (because it occurs
/// lexically later in the function).
// Note: Should also be a dense map from source block to the rest of the
// data if we expect many gotos.
std::vector<GotoJump> unresolvedGotos;
/// Caches landing pads generated for catches at this cleanup scope level
/// (null if not yet emitted, one element is pushed to/popped from the back
/// on entering/leaving a catch block).
/// Caches landing pads generated for catches at this cleanup scope level.
///
/// One element is pushed to the back on each time a catch block is entered,
/// and popped again once it is left. If the corresponding landing pad has
/// not been generated yet (this is done lazily), the pointer is null.
std::vector<llvm::BasicBlock*> landingPads;
};
/// Stores information to be able to branch to a catch clause if it matches.
///
/// Each catch body is emitted only once, but may be target from many landing
/// pads (in case of nested catch or cleanup scopes).
struct CatchScope {
/// The ClassInfo reference corresponding to the type to match the
/// exception object against.
@ -139,34 +156,49 @@ struct CatchScope {
/// The block to branch to if the exception type matches.
llvm::BasicBlock* bodyBlock;
/// The cleanup scope level corresponding to this catch.
/// The cleanup scope stack level corresponding to this catch.
CleanupCursor cleanupScope;
};
/// Contains transitory information about the current scope, etc. while
/// traversing the function for codegen purposes.
/// Keeps track of active (abstract) scopes in a function that influence code
/// generation of their contents. This includes cleanups (finally blocks,
/// destructors), try/catch blocks and labels for goto/break/continue.
///
/// Note that the entire code generation process, and this class in particular,
/// depends heavily on the fact that we visit the statement/expression tree in
/// its natural order, i.e. depth-first and in lexical order. In other words,
/// the code here expects that after a cleanup/catch/loop/etc. has been pushed,
/// the contents of the block are generated, and it is then popped again
/// afterwards. This is also encoded in the fact that none of the methods for
/// branching/running cleanups take a cursor for describing the "source" scope,
/// it is always assumed to be the current one.
///
/// Handling of break/continue could be moved into a separate layer that uses
/// the rest of the ScopeStack API, as it (in contrast to goto) never requires
/// resolving forward references across cleanup scopes.
class ScopeStack {
public:
ScopeStack(IRState *irs) : irs(irs) {}
ScopeStack(IRState* irs) : irs(irs) {}
~ScopeStack();
/// Registers a piece of cleanup code to be run.
///
/// The basic block is expected not to contain a terminator yet. It will be
/// added by ScopeStack as needed based on what followup blocks there will be
/// registered.
/// The end block is expected not to contain a terminator yet. It will be
/// added by ScopeStack as needed, based on what follow-up blocks code from
/// within this scope will branch to.
void pushCleanup(llvm::BasicBlock* beginBlock, llvm::BasicBlock* endBlock);
/// Terminates the current IRScope with a branch to the cleanups needed for
/// leaving the current scope and continuing execution at the target scope
/// stack level.
/// Terminates the current basic block with a branch to the cleanups needed
/// for leaving the current scope and continuing execution at the target
/// scope stack level.
///
/// After running them, execution will branch to the given basic block.
void runCleanups(CleanupCursor targetScope, llvm::BasicBlock* continueWith) {
runCleanups(currentCleanupScope(), targetScope, continueWith);
}
/// Like #runCleanups(), but runs all of them.
/// Like #runCleanups(), but runs all of them until the top-level scope is
/// reached.
void runAllCleanups(llvm::BasicBlock* continueWith);
/// Pops all the cleanups between the current scope and the target cursor.
@ -174,26 +206,28 @@ public:
/// This does not insert any cleanup calls, use #runCleanups() beforehand.
void popCleanups(CleanupCursor targetScope);
/// Returns a cursor that identifies the curernt cleanup scope, to be later
/// userd with #runCleanups() et al.
/// Returns a cursor that identifies the current cleanup scope, to be later
/// used with #runCleanups() et al.
///
/// Note that this cursor is only valid as long as the current scope is not
/// popped.
CleanupCursor currentCleanupScope() { return cleanupScopes.size(); }
/// Registers a catch block to be taken into consideration when an exception
/// is thrown within the current scope.
///
/// When a potentially throwing function call is emitted, a landing pad will
/// be emitted to compare the dynamic type info of the exception against the
/// given ClassInfo constant and to branch to the given body block if it
/// matches. The registered catch blocks are maintained on a stack, with the
/// top-most (i.e. last pushed, innermost) taking precedence.
void pushCatch(llvm::Constant* classInfoPtr, llvm::BasicBlock* bodyBlock);
///
/// Unregisters the last registered catch block.
void popCatch();
/// Emits a call or invoke to the given callee, depending on whether there
/// are catches/cleanups active or not.
template <typename T>
llvm::CallSite callOrInvoke(llvm::Value* callee, const T &args,
const char* name = "");
///
/// Registers a loop statement to be used as a target for break/continue
/// statements in the current scope.
void pushLoopTarget(Statement* loopStatement, llvm::BasicBlock* continueTarget,
llvm::BasicBlock* breakTarget);
@ -201,34 +235,55 @@ public:
/// consideration for resolving breaks/continues.
void popLoopTarget();
///
/// Registers a statement to be used as a target for break statements in the
/// current scope (currently applies only to switch statements).
void pushBreakTarget(Statement* switchStatement, llvm::BasicBlock* targetBlock);
///
/// Unregisters the last registered break target.
void popBreakTarget();
/// Adds a label to serve as a target for goto statements.
///
/// Also causes in-flight forward references to this label to be resolved.
void addLabelTarget(Identifier* labelName, llvm::BasicBlock* targetBlock);
/// Emits a call or invoke to the given callee, depending on whether there
/// are catches/cleanups active or not.
template <typename T>
llvm::CallSite callOrInvoke(llvm::Value* callee, const T &args,
const char* name = "");
/// Terminates the current basic block with an unconditional branch to the
/// given label, along with the cleanups to execute on the way there.
///
/// Legal forward references (i.e. within the same function, and not into
/// a cleanup scope) will be resolved.
void jumpToLabel(Loc loc, Identifier* labelName);
///
/// Terminates the current basic block with an unconditional branch to the
/// continue target generated by the given loop statement, along with
/// the cleanups to execute on the way there.
void continueWithLoop(Statement* loopStatement) {
jumpToStatement(continueTargets, loopStatement);
}
///
/// Terminates the current basic block with an unconditional branch to the
/// closest loop continue target, along with the cleanups to execute on
/// the way there.
void continueWithClosest() {
jumpToClosest(continueTargets);
}
///
/// Terminates the current basic block with an unconditional branch to the
/// break target generated by the given loop or switch statement, along with
/// the cleanups to execute on the way there.
void breakToStatement(Statement* loopOrSwitchStatement) {
jumpToStatement(breakTargets, loopOrSwitchStatement);
}
///
/// Terminates the current basic block with an unconditional branch to the
/// closest break statement target, along with the cleanups to execute on
/// the way there.
void breakToClosest() {
jumpToClosest(breakTargets);
}
@ -254,7 +309,7 @@ private:
/// The ambient IRState. For legacy reasons, there is currently a cyclic
/// dependency between the two.
IRState *irs;
IRState* irs;
typedef llvm::DenseMap<Identifier*, JumpTarget> LabelTargetMap;
/// The labels we have encountered in this function so far, accessed by
@ -344,6 +399,7 @@ struct IrFunction {
FuncDeclaration* decl;
TypeFunction* type;
/// Points to the associated scope stack while emitting code for the function.
ScopeStack* scopes;
bool queued;
@ -371,7 +427,7 @@ struct IrFunction {
/// A stack slot containing the exception object pointer while a landing pad
/// is active. Need this because the instruction must dominate all uses as a
/// _d_eh_resume_unwind parameter, but if we take a select at the end on a
/// cleanup on the way there, it also must dominate all other precedessors
/// cleanup on the way there, it also must dominate all other predecessors
/// of the cleanup. Thus, we just create an alloca at the start of the
/// function.
llvm::AllocaInst* ehPtrSlot;
@ -398,7 +454,7 @@ struct IrFunction {
IrFuncTy irFty;
};
IrFunction *getIrFunc(FuncDeclaration *decl, bool create = false);
bool isIrFuncCreated(FuncDeclaration *decl);
IrFunction* getIrFunc(FuncDeclaration* decl, bool create = false);
bool isIrFuncCreated(FuncDeclaration* decl);
#endif