The Indexes Patch.

This introduces a new pass, SlotIndexes, which is responsible for numbering
instructions for register allocation (and other clients). SlotIndexes numbering
is designed to match the existing scheme, so this patch should not cause any
changes in the generated code.

For consistency, and to avoid naming confusion, LiveIndex has been renamed
SlotIndex.

The processImplicitDefs method of the LiveIntervals analysis has been moved
into its own pass so that it can be run prior to SlotIndexes. This was
necessary to match the existing numbering scheme.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85979 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 189 insertions, 0 deletions

diff --git a/lib/CodeGen/SlotIndexes.cpp b/lib/CodeGen/SlotIndexes.cpp
new file mode 100644
index 0000000000..6b04029fba
--- /dev/null
+++ b/lib/CodeGen/SlotIndexes.cpp
@@ -0,0 +1,189 @@
+//===-- SlotIndexes.cpp - Slot Indexes Pass  ------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "slotindexes"
+
+#include "llvm/CodeGen/SlotIndexes.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+std::auto_ptr<IndexListEntry> SlotIndex::emptyKeyPtr(0),
+                              SlotIndex::tombstoneKeyPtr(0);
+
+char SlotIndexes::ID = 0;
+static RegisterPass<SlotIndexes> X("slotindexes", "Slot index numbering");
+
+void SlotIndexes::getAnalysisUsage(AnalysisUsage &au) const {
+  au.setPreservesAll();
+  MachineFunctionPass::getAnalysisUsage(au);
+}
+
+void SlotIndexes::releaseMemory() {
+  mi2iMap.clear();
+  mbb2IdxMap.clear();
+  idx2MBBMap.clear();
+  terminatorGaps.clear();
+  clearList();
+}
+
+bool SlotIndexes::runOnMachineFunction(MachineFunction &fn) {
+
+  // Compute numbering as follows:
+  // Grab an iterator to the start of the index list.
+  // Iterate over all MBBs, and within each MBB all MIs, keeping the MI
+  // iterator in lock-step (though skipping it over indexes which have
+  // null pointers in the instruction field).
+  // At each iteration assert that the instruction pointed to in the index
+  // is the same one pointed to by the MI iterator. This 
+
+  // FIXME: This can be simplified. The mi2iMap_, Idx2MBBMap, etc. should
+  // only need to be set up once after the first numbering is computed.
+
+  mf = &fn;
+  initList();
+
+  const unsigned gap = 1;
+
+  // Check that the list contains only the sentinal.
+  assert(indexListHead->getNext() == 0 &&
+         "Index list non-empty at initial numbering?");
+  assert(idx2MBBMap.empty() &&
+         "Index -> MBB mapping non-empty at initial numbering?");
+  assert(mbb2IdxMap.empty() &&
+         "MBB -> Index mapping non-empty at initial numbering?");
+  assert(mi2iMap.empty() &&
+         "MachineInstr -> Index mapping non-empty at initial numbering?");
+
+  functionSize = 0;
+  /*  
+  for (unsigned s = 0; s < SlotIndex::NUM; ++s) {  
+    indexList.push_back(createEntry(0, s));
+  }
+
+  unsigned index = gap * SlotIndex::NUM;
+  */
+
+  unsigned index = 0;
+
+  // Iterate over the the function.
+  for (MachineFunction::iterator mbbItr = mf->begin(), mbbEnd = mf->end();
+       mbbItr != mbbEnd; ++mbbItr) {
+    MachineBasicBlock *mbb = &*mbbItr;
+
+    // Insert an index for the MBB start.
+    push_back(createEntry(0, index));
+    SlotIndex blockStartIndex(back(), SlotIndex::LOAD);
+
+    index += gap * SlotIndex::NUM;
+
+    for (MachineBasicBlock::iterator miItr = mbb->begin(), miEnd = mbb->end();
+         miItr != miEnd; ++miItr) {
+      MachineInstr *mi = &*miItr;
+
+      if (miItr == mbb->getFirstTerminator()) {
+        push_back(createEntry(0, index));
+        terminatorGaps.insert(
+          std::make_pair(mbb, SlotIndex(back(), SlotIndex::PHI_BIT)));
+        index += gap * SlotIndex::NUM;
+      }
+
+      // Insert a store index for the instr.
+      push_back(createEntry(mi, index));
+
+      // Save this base index in the maps.
+      mi2iMap.insert(
+        std::make_pair(mi, SlotIndex(back(), SlotIndex::LOAD)));
+ 
+      ++functionSize;
+
+      unsigned Slots = mi->getDesc().getNumDefs();
+      if (Slots == 0)
+        Slots = 1;
+
+      index += (Slots + 1) * gap * SlotIndex::NUM;
+    }
+
+    if (mbb->getFirstTerminator() == mbb->end()) {
+      push_back(createEntry(0, index));
+      terminatorGaps.insert(
+        std::make_pair(mbb, SlotIndex(back(), SlotIndex::PHI_BIT)));
+      index += gap * SlotIndex::NUM;
+    }
+
+    SlotIndex blockEndIndex(back(), SlotIndex::STORE);
+    mbb2IdxMap.insert(
+      std::make_pair(mbb, std::make_pair(blockStartIndex, blockEndIndex)));
+
+    idx2MBBMap.push_back(IdxMBBPair(blockStartIndex, mbb));
+  }
+
+  // One blank instruction at the end.
+  push_back(createEntry(0, index));
+
+  // Sort the Idx2MBBMap
+  std::sort(idx2MBBMap.begin(), idx2MBBMap.end(), Idx2MBBCompare());
+
+  DEBUG(dump());
+
+  // And we're done!
+  return false;
+}
+
+void SlotIndexes::renumber() {
+  assert(false && "SlotIndexes::runmuber is not fully implemented yet.");
+
+  // Compute numbering as follows:
+  // Grab an iterator to the start of the index list.
+  // Iterate over all MBBs, and within each MBB all MIs, keeping the MI
+  // iterator in lock-step (though skipping it over indexes which have
+  // null pointers in the instruction field).
+  // At each iteration assert that the instruction pointed to in the index
+  // is the same one pointed to by the MI iterator. This 
+
+  // FIXME: This can be simplified. The mi2iMap_, Idx2MBBMap, etc. should
+  // only need to be set up once - when the first numbering is computed.
+
+  assert(false && "Renumbering not supported yet.");
+}
+
+void SlotIndexes::dump() const {
+  for (const IndexListEntry *itr = front(); itr != getTail();
+       itr = itr->getNext()) {
+    errs() << itr->getIndex() << " ";
+
+    if (itr->getInstr() != 0) {
+      errs() << *itr->getInstr();
+    } else {
+      errs() << "\n";
+    }
+  }
+
+  for (MBB2IdxMap::iterator itr = mbb2IdxMap.begin();
+       itr != mbb2IdxMap.end(); ++itr) {
+    errs() << "MBB " << itr->first->getNumber() << " (" << itr->first << ") - ["
+           << itr->second.first << ", " << itr->second.second << "]\n";
+  }
+}
+
+// Print a SlotIndex to a raw_ostream.
+void SlotIndex::print(raw_ostream &os) const {
+  os << getIndex();
+  if (isPHI())
+    os << "*";
+}
+
+// Dump a SlotIndex to stderr.
+void SlotIndex::dump() const {
+  print(errs());
+  errs() << "\n";
+}
+