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Revert "Fix post-dominator tree in stack promotion"

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This broke the test suite under optimizations with a SIL verifier error: "stack dealloc does
not match most recent stack alloc".

This reverts commit 7a2ca23bc2, reversing
changes made to 4c55e8d7a7.
This commit is contained in:
Jordan Rose
2016-04-06 16:02:20 -07:00
parent b0d54b1f07
commit 52b961de61
3 changed files with 12 additions and 169 deletions
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136
lib/SILOptimizer/Transforms/StackPromotion.cpp
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@@ -17,9 +17,6 @@
#include "swift/SILOptimizer/Analysis/DominanceAnalysis.h"
#include "swift/SIL/SILArgument.h"
#include "swift/SIL/SILBuilder.h"
#include "swift/SIL/CFG.h"
#include "llvm/Support/GenericDomTree.h"
#include "llvm/Support/GenericDomTreeConstruction.h"
#include "llvm/ADT/Statistic.h"
STATISTIC(NumStackPromoted, "Number of objects promoted to the stack");
@@ -51,23 +48,9 @@ class StackPromoter {
SILFunction *F;
EscapeAnalysis::ConnectionGraph *ConGraph;
DominanceInfo *DT;
PostDominanceInfo *PDT;
EscapeAnalysis *EA;
// We use our own post-dominator tree instead of PostDominatorAnalysis,
// because we ignore unreachable blocks (actually all unreachable sub-graphs).
// Example:
// |
// bb1
// / \
// unreachable bb2
// \
//
// We want to get bb2 as immediate post-domiator of bb1. This is not the case
// with the regualar post-dominator tree.
llvm::DominatorTreeBase<SILBasicBlock> PostDomTree;
bool PostDomTreeValid;
// Pseudo-functions for (de-)allocating array buffers on the stack.
SILFunction *BufferAllocFunc = nullptr;
@@ -142,18 +125,11 @@ class StackPromoter {
}
bool strictlyPostDominates(SILBasicBlock *A, SILBasicBlock *B) {
calculatePostDomTree();
return A != B && PostDomTree.dominates(A, B);
}
bool postDominates(SILBasicBlock *A, SILBasicBlock *B) {
calculatePostDomTree();
return PostDomTree.dominates(A, B);
return A != B && PDT->dominates(A, B);
}
SILBasicBlock *getImmediatePostDom(SILBasicBlock *BB) {
calculatePostDomTree();
auto *Node = PostDomTree.getNode(BB);
auto *Node = PDT->getNode(BB);
if (!Node)
return nullptr;
auto *IDomNode = Node->getIDom();
@@ -161,22 +137,13 @@ class StackPromoter {
return nullptr;
return IDomNode->getBlock();
}
void calculatePostDomTree() {
if (!PostDomTreeValid) {
// The StackPromoter acts as a "graph" for which the post-dominator-tree
// is calculated.
PostDomTree.recalculate(*this);
PostDomTreeValid = true;
}
}
public:
StackPromoter(SILFunction *F, EscapeAnalysis::ConnectionGraph *ConGraph,
DominanceInfo *DT, EscapeAnalysis *EA) :
F(F), ConGraph(ConGraph), DT(DT), EA(EA), PostDomTree(true),
PostDomTreeValid(false) { }
DominanceInfo *DT, PostDominanceInfo *PDT,
EscapeAnalysis *EA) :
F(F), ConGraph(ConGraph), DT(DT), PDT(PDT), EA(EA) { }
/// What did the optimization change?
enum class ChangeState {
@@ -185,8 +152,6 @@ public:
Calls
};
SILFunction *getFunction() const { return F; }
/// The main entry point for the optimization.
ChangeState promote();
};
@@ -319,87 +284,6 @@ SILFunction *StackPromoter::getBufferDeallocFunc(SILFunction *OrigFunc,
return BufferDeallocFunc;
}
namespace {
/// Iterator which iterates over all basic blocks of a function which are not
/// terminated by an unreachable inst.
class NonUnreachableBlockIter :
public std::iterator<std::forward_iterator_tag, SILBasicBlock, ptrdiff_t> {
SILFunction::iterator BaseIterator;
SILFunction::iterator End;
void skipUnreachables() {
while (true) {
if (BaseIterator == End)
return;
if (!isa<UnreachableInst>(BaseIterator->getTerminator()))
return;
BaseIterator++;
}
}
public:
NonUnreachableBlockIter(SILFunction::iterator BaseIterator,
SILFunction::iterator End) :
BaseIterator(BaseIterator), End(End) {
skipUnreachables();
}
NonUnreachableBlockIter() = default;
SILBasicBlock &operator*() const { return *BaseIterator; }
SILBasicBlock &operator->() const { return *BaseIterator; }
NonUnreachableBlockIter &operator++() {
BaseIterator++;
skipUnreachables();
return *this;
}
NonUnreachableBlockIter operator++(int unused) {
NonUnreachableBlockIter Copy = *this;
++*this;
return Copy;
}
friend bool operator==(NonUnreachableBlockIter lhs,
NonUnreachableBlockIter rhs) {
return lhs.BaseIterator == rhs.BaseIterator;
}
friend bool operator!=(NonUnreachableBlockIter lhs,
NonUnreachableBlockIter rhs) {
return !(lhs == rhs);
}
};
}
namespace llvm {
/// Use the StackPromoter as a wrapper for the function. It holds the list of
/// basic blocks excluding all unreachable blocks.
template <> struct GraphTraits<StackPromoter *>
: public GraphTraits<swift::SILBasicBlock*> {
typedef StackPromoter *GraphType;
static NodeType *getEntryNode(GraphType SP) {
return &SP->getFunction()->front();
}
typedef NonUnreachableBlockIter nodes_iterator;
static nodes_iterator nodes_begin(GraphType SP) {
return nodes_iterator(SP->getFunction()->begin(), SP->getFunction()->end());
}
static nodes_iterator nodes_end(GraphType SP) {
return nodes_iterator(SP->getFunction()->end(), SP->getFunction()->end());
}
static unsigned size(GraphType SP) {
return std::distance(nodes_begin(SP), nodes_end(SP));
}
};
}
bool StackPromoter::canPromoteAlloc(SILInstruction *AI,
SILInstruction *&AllocInsertionPoint,
SILInstruction *&DeallocInsertionPoint) {
@@ -510,7 +394,7 @@ bool StackPromoter::canPromoteAlloc(SILInstruction *AI,
if (!Alloc)
return false;
// This should always be the case, but let's be on the safe side.
if (!postDominates(StartBlock, Alloc->getParent()))
if (!PDT->dominates(StartBlock, Alloc->getParent()))
return false;
AllocInsertionPoint = Alloc;
StackDepth++;
@@ -582,18 +466,20 @@ private:
auto *EA = PM->getAnalysis<EscapeAnalysis>();
auto *DA = PM->getAnalysis<DominanceAnalysis>();
auto *PDA = PM->getAnalysis<PostDominanceAnalysis>();
SILFunction *F = getFunction();
if (auto *ConGraph = EA->getConnectionGraph(F)) {
StackPromoter promoter(F, ConGraph, DA->get(F), EA);
StackPromoter promoter(F, ConGraph, DA->get(F), PDA->get(F), EA);
switch (promoter.promote()) {
case StackPromoter::ChangeState::None:
break;
case StackPromoter::ChangeState::Insts:
invalidateAnalysis(SILAnalysis::InvalidationKind::Instructions);
break;
case StackPromoter::ChangeState::Calls:
case StackPromoter::ChangeState::Calls: {
invalidateAnalysis(SILAnalysis::InvalidationKind::CallsAndInstructions);
}
break;
}
}