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//===--- Dominance.cpp - SIL basic block dominance analysis ---------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
#include "swift/SIL/SILFunction.h"
#include "swift/SIL/SILBasicBlock.h"
#include "swift/SIL/SILArgument.h"
#include "swift/SIL/Dominance.h"
#include "llvm/Support/GenericDomTreeConstruction.h"
using namespace swift;
template class llvm::DominatorTreeBase<SILBasicBlock, false>;
template class llvm::DominatorTreeBase<SILBasicBlock, true>;
template class llvm::DomTreeNodeBase<SILBasicBlock>;
namespace llvm {
namespace DomTreeBuilder {
template void Calculate<SILDomTree>(SILDomTree &DT);
template void Calculate<SILPostDomTree>(SILPostDomTree &DT);
} // namespace DomTreeBuilder
} // namespace llvm
/// Compute the immediate-dominators map.
DominanceInfo::DominanceInfo(SILFunction *F)
: DominatorTreeBase() {
assert(!F->isExternalDeclaration() &&
"Make sure the function is a definition and not a declaration.");
recalculate(*F);
}
DominanceInfo::~DominanceInfo() {
}
bool DominanceInfo::properlyDominates(SILInstruction *a, SILInstruction *b) {
auto aBlock = a->getParent(), bBlock = b->getParent();
// If the blocks are different, it's as easy as whether A's block
// dominates B's block.
if (aBlock != bBlock)
return properlyDominates(a->getParent(), b->getParent());
// Otherwise, they're in the same block, and we just need to check
// whether B comes after A. This is a non-strict computation.
auto aIter = a->getIterator();
auto bIter = b->getIterator();
auto fIter = aBlock->begin();
while (bIter != fIter) {
--bIter;
if (aIter == bIter)
return true;
}
return false;
}
/// Does value A properly dominate instruction B?
bool DominanceInfo::properlyDominates(SILValue a, SILInstruction *b) {
if (auto *Inst = a->getDefiningInstruction()) {
return properlyDominates(Inst, b);
}
if (auto *Arg = dyn_cast<SILArgument>(a)) {
return dominates(Arg->getParent(), b->getParent());
}
return false;
}
SILBasicBlock *DominanceInfo::getLeastCommonAncestorOfUses(SILValue value) {
SILBasicBlock *lca = nullptr;
for (auto *use : value->getUses()) {
auto *block = use->getParentBlock();
lca = lca ? findNearestCommonDominator(lca, block) : block;
}
return lca;
}
void DominanceInfo::verify() const {
// Recompute.
auto *F = getRoot()->getParent();
DominanceInfo OtherDT(F);
// And compare.
if (errorOccurredOnComparison(OtherDT)) {
llvm::errs() << "DominatorTree is not up to date!\nComputed:\n";
print(llvm::errs());
llvm::errs() << "\nActual:\n";
OtherDT.print(llvm::errs());
abort();
}
}
/// Compute the immediate-post-dominators map.
PostDominanceInfo::PostDominanceInfo(SILFunction *F)
: PostDominatorTreeBase() {
assert(!F->isExternalDeclaration() &&
"Cannot construct a post dominator tree for a declaration");
recalculate(*F);
}
bool
PostDominanceInfo::
properlyDominates(SILInstruction *I1, SILInstruction *I2) {
SILBasicBlock *BB1 = I1->getParent(), *BB2 = I2->getParent();
// If the blocks are different, it's as easy as whether BB1 post dominates
// BB2.
if (BB1 != BB2)
return properlyDominates(BB1, BB2);
// Otherwise, they're in the same block, and we just need to check
// whether A comes after B.
for (auto II = I1->getIterator(), IE = BB1->end(); II != IE; ++II) {
if (&*II == I2) {
return false;
}
}
return true;
}
bool PostDominanceInfo::properlyDominates(SILValue A, SILInstruction *B) {
if (auto *Inst = A->getDefiningInstruction()) {
return properlyDominates(Inst, B);
}
if (auto *Arg = dyn_cast<SILArgument>(A)) {
return dominates(Arg->getParent(), B->getParent());
}
return false;
}
void PostDominanceInfo::verify() const {
// Recompute.
//
// Even though at the SIL level we have "one" return function, we can have
// multiple exits provided by no-return functions.
auto *F = (*root_begin())->getParent();
PostDominanceInfo OtherDT(F);
// And compare.
if (errorOccurredOnComparison(OtherDT)) {
llvm::errs() << "PostDominatorTree is not up to date!\nComputed:\n";
print(llvm::errs());
llvm::errs() << "\nActual:\n";
OtherDT.print(llvm::errs());
abort();
}
}
void swift::computeDominatedBoundaryBlocks(
SILBasicBlock *root, DominanceInfo *domTree,
SmallVectorImpl<SILBasicBlock *> &boundary) {
assert(boundary.empty());
DominanceOrder domOrder(root, domTree);
while (SILBasicBlock *block = domOrder.getNext()) {
DominanceInfoNode *domNode = domTree->getNode(block);
if (!domNode->isLeaf()) {
domOrder.pushChildren(block);
continue;
}
if (block->getNumSuccessors() == 0) {
boundary.push_back(block);
continue;
}
auto *succ = block->getSingleSuccessorBlock();
if (!domTree->properlyDominates(root, succ)) {
boundary.push_back(block);
}
}
}
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