WebAssemblyAsmPrinter.cpp
WebAssemblyCallIndirectFixup.cpp
WebAssemblyCFGStackify.cpp
+ WebAssemblyCFGSort.cpp
WebAssemblyExplicitLocals.cpp
WebAssemblyFastISel.cpp
WebAssemblyFixIrreducibleControlFlow.cpp
FunctionPass *createWebAssemblyRegColoring();
FunctionPass *createWebAssemblyExplicitLocals();
FunctionPass *createWebAssemblyFixIrreducibleControlFlow();
+FunctionPass *createWebAssemblyCFGSort();
FunctionPass *createWebAssemblyCFGStackify();
FunctionPass *createWebAssemblyLowerBrUnless();
FunctionPass *createWebAssemblyRegNumbering();
--- /dev/null
+//===-- WebAssemblyCFGSort.cpp - CFG Sorting ------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief This file implements a CFG sorting pass.
+///
+/// This pass reorders the blocks in a function to put them into topological
+/// order, ignoring loop backedges, and without any loop being interrupted
+/// by a block not dominated by the loop header, with special care to keep the
+/// order as similar as possible to the original order.
+///
+////===----------------------------------------------------------------------===//
+
+#include "WebAssembly.h"
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "WebAssemblySubtarget.h"
+#include "WebAssemblyUtilities.h"
+#include "llvm/ADT/PriorityQueue.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/CodeGen/MachineDominators.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-cfg-sort"
+
+namespace {
+class WebAssemblyCFGSort final : public MachineFunctionPass {
+ StringRef getPassName() const override { return "WebAssembly CFG Sort"; }
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.setPreservesCFG();
+ AU.addRequired<MachineDominatorTree>();
+ AU.addPreserved<MachineDominatorTree>();
+ AU.addRequired<MachineLoopInfo>();
+ AU.addPreserved<MachineLoopInfo>();
+ MachineFunctionPass::getAnalysisUsage(AU);
+ }
+
+ bool runOnMachineFunction(MachineFunction &MF) override;
+
+public:
+ static char ID; // Pass identification, replacement for typeid
+ WebAssemblyCFGSort() : MachineFunctionPass(ID) {}
+};
+} // end anonymous namespace
+
+char WebAssemblyCFGSort::ID = 0;
+FunctionPass *llvm::createWebAssemblyCFGSort() {
+ return new WebAssemblyCFGSort();
+}
+
+static void MaybeUpdateTerminator(MachineBasicBlock *MBB) {
+#ifndef NDEBUG
+ bool AnyBarrier = false;
+#endif
+ bool AllAnalyzable = true;
+ for (const MachineInstr &Term : MBB->terminators()) {
+#ifndef NDEBUG
+ AnyBarrier |= Term.isBarrier();
+#endif
+ AllAnalyzable &= Term.isBranch() && !Term.isIndirectBranch();
+ }
+ assert((AnyBarrier || AllAnalyzable) &&
+ "AnalyzeBranch needs to analyze any block with a fallthrough");
+ if (AllAnalyzable)
+ MBB->updateTerminator();
+}
+
+namespace {
+/// Sort blocks by their number.
+struct CompareBlockNumbers {
+ bool operator()(const MachineBasicBlock *A,
+ const MachineBasicBlock *B) const {
+ return A->getNumber() > B->getNumber();
+ }
+};
+/// Sort blocks by their number in the opposite order..
+struct CompareBlockNumbersBackwards {
+ bool operator()(const MachineBasicBlock *A,
+ const MachineBasicBlock *B) const {
+ return A->getNumber() < B->getNumber();
+ }
+};
+/// Bookkeeping for a loop to help ensure that we don't mix blocks not dominated
+/// by the loop header among the loop's blocks.
+struct Entry {
+ const MachineLoop *Loop;
+ unsigned NumBlocksLeft;
+
+ /// List of blocks not dominated by Loop's header that are deferred until
+ /// after all of Loop's blocks have been seen.
+ std::vector<MachineBasicBlock *> Deferred;
+
+ explicit Entry(const MachineLoop *L)
+ : Loop(L), NumBlocksLeft(L->getNumBlocks()) {}
+};
+} // end anonymous namespace
+
+/// Sort the blocks, taking special care to make sure that loops are not
+/// interrupted by blocks not dominated by their header.
+/// TODO: There are many opportunities for improving the heuristics here.
+/// Explore them.
+static void SortBlocks(MachineFunction &MF, const MachineLoopInfo &MLI,
+ const MachineDominatorTree &MDT) {
+ // Prepare for a topological sort: Record the number of predecessors each
+ // block has, ignoring loop backedges.
+ MF.RenumberBlocks();
+ SmallVector<unsigned, 16> NumPredsLeft(MF.getNumBlockIDs(), 0);
+ for (MachineBasicBlock &MBB : MF) {
+ unsigned N = MBB.pred_size();
+ if (MachineLoop *L = MLI.getLoopFor(&MBB))
+ if (L->getHeader() == &MBB)
+ for (const MachineBasicBlock *Pred : MBB.predecessors())
+ if (L->contains(Pred))
+ --N;
+ NumPredsLeft[MBB.getNumber()] = N;
+ }
+
+ // Topological sort the CFG, with additional constraints:
+ // - Between a loop header and the last block in the loop, there can be
+ // no blocks not dominated by the loop header.
+ // - It's desirable to preserve the original block order when possible.
+ // We use two ready lists; Preferred and Ready. Preferred has recently
+ // processed sucessors, to help preserve block sequences from the original
+ // order. Ready has the remaining ready blocks.
+ PriorityQueue<MachineBasicBlock *, std::vector<MachineBasicBlock *>,
+ CompareBlockNumbers>
+ Preferred;
+ PriorityQueue<MachineBasicBlock *, std::vector<MachineBasicBlock *>,
+ CompareBlockNumbersBackwards>
+ Ready;
+ SmallVector<Entry, 4> Loops;
+ for (MachineBasicBlock *MBB = &MF.front();;) {
+ const MachineLoop *L = MLI.getLoopFor(MBB);
+ if (L) {
+ // If MBB is a loop header, add it to the active loop list. We can't put
+ // any blocks that it doesn't dominate until we see the end of the loop.
+ if (L->getHeader() == MBB)
+ Loops.push_back(Entry(L));
+ // For each active loop the block is in, decrement the count. If MBB is
+ // the last block in an active loop, take it off the list and pick up any
+ // blocks deferred because the header didn't dominate them.
+ for (Entry &E : Loops)
+ if (E.Loop->contains(MBB) && --E.NumBlocksLeft == 0)
+ for (auto DeferredBlock : E.Deferred)
+ Ready.push(DeferredBlock);
+ while (!Loops.empty() && Loops.back().NumBlocksLeft == 0)
+ Loops.pop_back();
+ }
+ // The main topological sort logic.
+ for (MachineBasicBlock *Succ : MBB->successors()) {
+ // Ignore backedges.
+ if (MachineLoop *SuccL = MLI.getLoopFor(Succ))
+ if (SuccL->getHeader() == Succ && SuccL->contains(MBB))
+ continue;
+ // Decrement the predecessor count. If it's now zero, it's ready.
+ if (--NumPredsLeft[Succ->getNumber()] == 0)
+ Preferred.push(Succ);
+ }
+ // Determine the block to follow MBB. First try to find a preferred block,
+ // to preserve the original block order when possible.
+ MachineBasicBlock *Next = nullptr;
+ while (!Preferred.empty()) {
+ Next = Preferred.top();
+ Preferred.pop();
+ // If X isn't dominated by the top active loop header, defer it until that
+ // loop is done.
+ if (!Loops.empty() &&
+ !MDT.dominates(Loops.back().Loop->getHeader(), Next)) {
+ Loops.back().Deferred.push_back(Next);
+ Next = nullptr;
+ continue;
+ }
+ // If Next was originally ordered before MBB, and it isn't because it was
+ // loop-rotated above the header, it's not preferred.
+ if (Next->getNumber() < MBB->getNumber() &&
+ (!L || !L->contains(Next) ||
+ L->getHeader()->getNumber() < Next->getNumber())) {
+ Ready.push(Next);
+ Next = nullptr;
+ continue;
+ }
+ break;
+ }
+ // If we didn't find a suitable block in the Preferred list, check the
+ // general Ready list.
+ if (!Next) {
+ // If there are no more blocks to process, we're done.
+ if (Ready.empty()) {
+ MaybeUpdateTerminator(MBB);
+ break;
+ }
+ for (;;) {
+ Next = Ready.top();
+ Ready.pop();
+ // If Next isn't dominated by the top active loop header, defer it until
+ // that loop is done.
+ if (!Loops.empty() &&
+ !MDT.dominates(Loops.back().Loop->getHeader(), Next)) {
+ Loops.back().Deferred.push_back(Next);
+ continue;
+ }
+ break;
+ }
+ }
+ // Move the next block into place and iterate.
+ Next->moveAfter(MBB);
+ MaybeUpdateTerminator(MBB);
+ MBB = Next;
+ }
+ assert(Loops.empty() && "Active loop list not finished");
+ MF.RenumberBlocks();
+
+#ifndef NDEBUG
+ SmallSetVector<MachineLoop *, 8> OnStack;
+
+ // Insert a sentinel representing the degenerate loop that starts at the
+ // function entry block and includes the entire function as a "loop" that
+ // executes once.
+ OnStack.insert(nullptr);
+
+ for (auto &MBB : MF) {
+ assert(MBB.getNumber() >= 0 && "Renumbered blocks should be non-negative.");
+
+ MachineLoop *Loop = MLI.getLoopFor(&MBB);
+ if (Loop && &MBB == Loop->getHeader()) {
+ // Loop header. The loop predecessor should be sorted above, and the other
+ // predecessors should be backedges below.
+ for (auto Pred : MBB.predecessors())
+ assert(
+ (Pred->getNumber() < MBB.getNumber() || Loop->contains(Pred)) &&
+ "Loop header predecessors must be loop predecessors or backedges");
+ assert(OnStack.insert(Loop) && "Loops should be declared at most once.");
+ } else {
+ // Not a loop header. All predecessors should be sorted above.
+ for (auto Pred : MBB.predecessors())
+ assert(Pred->getNumber() < MBB.getNumber() &&
+ "Non-loop-header predecessors should be topologically sorted");
+ assert(OnStack.count(MLI.getLoopFor(&MBB)) &&
+ "Blocks must be nested in their loops");
+ }
+ while (OnStack.size() > 1 && &MBB == LoopBottom(OnStack.back()))
+ OnStack.pop_back();
+ }
+ assert(OnStack.pop_back_val() == nullptr &&
+ "The function entry block shouldn't actually be a loop header");
+ assert(OnStack.empty() &&
+ "Control flow stack pushes and pops should be balanced.");
+#endif
+}
+
+bool WebAssemblyCFGSort::runOnMachineFunction(MachineFunction &MF) {
+ DEBUG(dbgs() << "********** CFG Sorting **********\n"
+ "********** Function: "
+ << MF.getName() << '\n');
+
+ const auto &MLI = getAnalysis<MachineLoopInfo>();
+ auto &MDT = getAnalysis<MachineDominatorTree>();
+ // Liveness is not tracked for VALUE_STACK physreg.
+ MF.getRegInfo().invalidateLiveness();
+
+ // Sort the blocks, with contiguous loops.
+ SortBlocks(MF, MLI, MDT);
+
+ return true;
+}
/// \file
/// \brief This file implements a CFG stacking pass.
///
-/// This pass reorders the blocks in a function to put them into topological
-/// order, ignoring loop backedges, and without any loop being interrupted
-/// by a block not dominated by the loop header, with special care to keep the
-/// order as similar as possible to the original order.
-///
-/// Then, it inserts BLOCK and LOOP markers to mark the start of scopes, since
+/// This pass inserts BLOCK and LOOP markers to mark the start of scopes, since
/// scope boundaries serve as the labels for WebAssembly's control transfers.
///
/// This is sufficient to convert arbitrary CFGs into a form that works on
#include "WebAssemblyMachineFunctionInfo.h"
#include "WebAssemblySubtarget.h"
#include "WebAssemblyUtilities.h"
-#include "llvm/ADT/PriorityQueue.h"
-#include "llvm/ADT/SetVector.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
return new WebAssemblyCFGStackify();
}
-/// Return the "bottom" block of a loop. This differs from
-/// MachineLoop::getBottomBlock in that it works even if the loop is
-/// discontiguous.
-static MachineBasicBlock *LoopBottom(const MachineLoop *Loop) {
- MachineBasicBlock *Bottom = Loop->getHeader();
- for (MachineBasicBlock *MBB : Loop->blocks())
- if (MBB->getNumber() > Bottom->getNumber())
- Bottom = MBB;
- return Bottom;
-}
-
-static void MaybeUpdateTerminator(MachineBasicBlock *MBB) {
-#ifndef NDEBUG
- bool AnyBarrier = false;
-#endif
- bool AllAnalyzable = true;
- for (const MachineInstr &Term : MBB->terminators()) {
-#ifndef NDEBUG
- AnyBarrier |= Term.isBarrier();
-#endif
- AllAnalyzable &= Term.isBranch() && !Term.isIndirectBranch();
- }
- assert((AnyBarrier || AllAnalyzable) &&
- "AnalyzeBranch needs to analyze any block with a fallthrough");
- if (AllAnalyzable)
- MBB->updateTerminator();
-}
-
-namespace {
-/// Sort blocks by their number.
-struct CompareBlockNumbers {
- bool operator()(const MachineBasicBlock *A,
- const MachineBasicBlock *B) const {
- return A->getNumber() > B->getNumber();
- }
-};
-/// Sort blocks by their number in the opposite order..
-struct CompareBlockNumbersBackwards {
- bool operator()(const MachineBasicBlock *A,
- const MachineBasicBlock *B) const {
- return A->getNumber() < B->getNumber();
- }
-};
-/// Bookkeeping for a loop to help ensure that we don't mix blocks not dominated
-/// by the loop header among the loop's blocks.
-struct Entry {
- const MachineLoop *Loop;
- unsigned NumBlocksLeft;
-
- /// List of blocks not dominated by Loop's header that are deferred until
- /// after all of Loop's blocks have been seen.
- std::vector<MachineBasicBlock *> Deferred;
-
- explicit Entry(const MachineLoop *L)
- : Loop(L), NumBlocksLeft(L->getNumBlocks()) {}
-};
-}
-
-/// Sort the blocks, taking special care to make sure that loops are not
-/// interrupted by blocks not dominated by their header.
-/// TODO: There are many opportunities for improving the heuristics here.
-/// Explore them.
-static void SortBlocks(MachineFunction &MF, const MachineLoopInfo &MLI,
- const MachineDominatorTree &MDT) {
- // Prepare for a topological sort: Record the number of predecessors each
- // block has, ignoring loop backedges.
- MF.RenumberBlocks();
- SmallVector<unsigned, 16> NumPredsLeft(MF.getNumBlockIDs(), 0);
- for (MachineBasicBlock &MBB : MF) {
- unsigned N = MBB.pred_size();
- if (MachineLoop *L = MLI.getLoopFor(&MBB))
- if (L->getHeader() == &MBB)
- for (const MachineBasicBlock *Pred : MBB.predecessors())
- if (L->contains(Pred))
- --N;
- NumPredsLeft[MBB.getNumber()] = N;
- }
-
- // Topological sort the CFG, with additional constraints:
- // - Between a loop header and the last block in the loop, there can be
- // no blocks not dominated by the loop header.
- // - It's desirable to preserve the original block order when possible.
- // We use two ready lists; Preferred and Ready. Preferred has recently
- // processed sucessors, to help preserve block sequences from the original
- // order. Ready has the remaining ready blocks.
- PriorityQueue<MachineBasicBlock *, std::vector<MachineBasicBlock *>,
- CompareBlockNumbers>
- Preferred;
- PriorityQueue<MachineBasicBlock *, std::vector<MachineBasicBlock *>,
- CompareBlockNumbersBackwards>
- Ready;
- SmallVector<Entry, 4> Loops;
- for (MachineBasicBlock *MBB = &MF.front();;) {
- const MachineLoop *L = MLI.getLoopFor(MBB);
- if (L) {
- // If MBB is a loop header, add it to the active loop list. We can't put
- // any blocks that it doesn't dominate until we see the end of the loop.
- if (L->getHeader() == MBB)
- Loops.push_back(Entry(L));
- // For each active loop the block is in, decrement the count. If MBB is
- // the last block in an active loop, take it off the list and pick up any
- // blocks deferred because the header didn't dominate them.
- for (Entry &E : Loops)
- if (E.Loop->contains(MBB) && --E.NumBlocksLeft == 0)
- for (auto DeferredBlock : E.Deferred)
- Ready.push(DeferredBlock);
- while (!Loops.empty() && Loops.back().NumBlocksLeft == 0)
- Loops.pop_back();
- }
- // The main topological sort logic.
- for (MachineBasicBlock *Succ : MBB->successors()) {
- // Ignore backedges.
- if (MachineLoop *SuccL = MLI.getLoopFor(Succ))
- if (SuccL->getHeader() == Succ && SuccL->contains(MBB))
- continue;
- // Decrement the predecessor count. If it's now zero, it's ready.
- if (--NumPredsLeft[Succ->getNumber()] == 0)
- Preferred.push(Succ);
- }
- // Determine the block to follow MBB. First try to find a preferred block,
- // to preserve the original block order when possible.
- MachineBasicBlock *Next = nullptr;
- while (!Preferred.empty()) {
- Next = Preferred.top();
- Preferred.pop();
- // If X isn't dominated by the top active loop header, defer it until that
- // loop is done.
- if (!Loops.empty() &&
- !MDT.dominates(Loops.back().Loop->getHeader(), Next)) {
- Loops.back().Deferred.push_back(Next);
- Next = nullptr;
- continue;
- }
- // If Next was originally ordered before MBB, and it isn't because it was
- // loop-rotated above the header, it's not preferred.
- if (Next->getNumber() < MBB->getNumber() &&
- (!L || !L->contains(Next) ||
- L->getHeader()->getNumber() < Next->getNumber())) {
- Ready.push(Next);
- Next = nullptr;
- continue;
- }
- break;
- }
- // If we didn't find a suitable block in the Preferred list, check the
- // general Ready list.
- if (!Next) {
- // If there are no more blocks to process, we're done.
- if (Ready.empty()) {
- MaybeUpdateTerminator(MBB);
- break;
- }
- for (;;) {
- Next = Ready.top();
- Ready.pop();
- // If Next isn't dominated by the top active loop header, defer it until
- // that loop is done.
- if (!Loops.empty() &&
- !MDT.dominates(Loops.back().Loop->getHeader(), Next)) {
- Loops.back().Deferred.push_back(Next);
- continue;
- }
- break;
- }
- }
- // Move the next block into place and iterate.
- Next->moveAfter(MBB);
- MaybeUpdateTerminator(MBB);
- MBB = Next;
- }
- assert(Loops.empty() && "Active loop list not finished");
- MF.RenumberBlocks();
-
-#ifndef NDEBUG
- SmallSetVector<MachineLoop *, 8> OnStack;
-
- // Insert a sentinel representing the degenerate loop that starts at the
- // function entry block and includes the entire function as a "loop" that
- // executes once.
- OnStack.insert(nullptr);
-
- for (auto &MBB : MF) {
- assert(MBB.getNumber() >= 0 && "Renumbered blocks should be non-negative.");
-
- MachineLoop *Loop = MLI.getLoopFor(&MBB);
- if (Loop && &MBB == Loop->getHeader()) {
- // Loop header. The loop predecessor should be sorted above, and the other
- // predecessors should be backedges below.
- for (auto Pred : MBB.predecessors())
- assert(
- (Pred->getNumber() < MBB.getNumber() || Loop->contains(Pred)) &&
- "Loop header predecessors must be loop predecessors or backedges");
- assert(OnStack.insert(Loop) && "Loops should be declared at most once.");
- } else {
- // Not a loop header. All predecessors should be sorted above.
- for (auto Pred : MBB.predecessors())
- assert(Pred->getNumber() < MBB.getNumber() &&
- "Non-loop-header predecessors should be topologically sorted");
- assert(OnStack.count(MLI.getLoopFor(&MBB)) &&
- "Blocks must be nested in their loops");
- }
- while (OnStack.size() > 1 && &MBB == LoopBottom(OnStack.back()))
- OnStack.pop_back();
- }
- assert(OnStack.pop_back_val() == nullptr &&
- "The function entry block shouldn't actually be a loop header");
- assert(OnStack.empty() &&
- "Control flow stack pushes and pops should be balanced.");
-#endif
-}
-
/// Test whether Pred has any terminators explicitly branching to MBB, as
/// opposed to falling through. Note that it's possible (eg. in unoptimized
/// code) for a branch instruction to both branch to a block and fallthrough
WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>();
MF.getRegInfo().invalidateLiveness();
- // Sort the blocks, with contiguous loops.
- SortBlocks(MF, MLI, MDT);
-
// Place the BLOCK and LOOP markers to indicate the beginnings of scopes.
PlaceMarkers(MF, MLI, TII, MDT, MFI);
// Insert explicit get_local and set_local operators.
addPass(createWebAssemblyExplicitLocals());
- // Put the CFG in structured form; insert BLOCK and LOOP markers.
+ // Sort the blocks of the CFG into topological order, a prerequisite for
+ // BLOCK and LOOP markers.
+ addPass(createWebAssemblyCFGSort());
+
+ // Insert BLOCK and LOOP markers.
addPass(createWebAssemblyCFGStackify());
// Lower br_unless into br_if.
#include "WebAssemblyUtilities.h"
#include "WebAssemblyMachineFunctionInfo.h"
#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
using namespace llvm;
bool WebAssembly::isArgument(const MachineInstr &MI) {
return false;
}
}
+
+MachineBasicBlock *llvm::LoopBottom(const MachineLoop *Loop) {
+ MachineBasicBlock *Bottom = Loop->getHeader();
+ for (MachineBasicBlock *MBB : Loop->blocks())
+ if (MBB->getNumber() > Bottom->getNumber())
+ Bottom = MBB;
+ return Bottom;
+}
namespace llvm {
+class MachineBasicBlock;
class MachineInstr;
+class MachineLoop;
class WebAssemblyFunctionInfo;
namespace WebAssembly {
bool isCallIndirect(const MachineInstr &MI);
} // end namespace WebAssembly
+
+/// Return the "bottom" block of a loop. This differs from
+/// MachineLoop::getBottomBlock in that it works even if the loop is
+/// discontiguous.
+MachineBasicBlock *LoopBottom(const MachineLoop *Loop);
+
} // end namespace llvm
#endif
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