Tighten the insert() API for bundled instructions.

The normal insert() function takes an MBB::iterator position, and
inserts a stand-alone MachineInstr as before.

The insert() function that takes an MBB::instr_iterator position can
insert instructions inside a bundle, and will now update the bundle
flags correctly when that happens.

When the insert position is between two bundles, it is unclear whether
the instruction should be appended to the previous bundle, prepended to
the next bundle, or stand on its own. The MBB::insert() function doesn't
bundle the instruction in that case, use the MIBundleBuilder class for
that.

llvm-svn: 170437

2 files changed, 32 insertions, 14 deletions

diff --git a/llvm/include/llvm/CodeGen/MachineBasicBlock.h b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
index 91dcf1c4c39..0a12de318fe 100644
--- a/llvm/include/llvm/CodeGen/MachineBasicBlock.h
+++ b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
@@ -441,26 +441,32 @@ public:
   void pop_back() { Insts.pop_back(); }
   void push_back(MachineInstr *MI) { Insts.push_back(MI); }
 
-  template<typename IT>
-  void insert(instr_iterator I, IT S, IT E) {
-    Insts.insert(I, S, E);
-  }
-  instr_iterator insert(instr_iterator I, MachineInstr *M) {
-    return Insts.insert(I, M);
-  }
-  instr_iterator insertAfter(instr_iterator I, MachineInstr *M) {
-    return Insts.insertAfter(I, M);
-  }
+  /// Insert MI into the instruction list before I, possibly inside a bundle.
+  ///
+  /// If the insertion point is inside a bundle, MI will be added to the bundle,
+  /// otherwise MI will not be added to any bundle. That means this function
+  /// alone can't be used to prepend or append instructions to bundles. See
+  /// MIBundleBuilder::insert() for a more reliable way of doing that.
+  instr_iterator insert(instr_iterator I, MachineInstr *M);
 
+  /// Insert a range of instructions into the instruction list before I.
   template<typename IT>
   void insert(iterator I, IT S, IT E) {
     Insts.insert(I.getInstrIterator(), S, E);
   }
-  iterator insert(iterator I, MachineInstr *M) {
-    return Insts.insert(I.getInstrIterator(), M);
+
+  /// Insert MI into the instruction list before I.
+  iterator insert(iterator I, MachineInstr *MI) {
+    assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
+           "Cannot insert instruction with bundle flags");
+    return Insts.insert(I.getInstrIterator(), MI);
   }
-  iterator insertAfter(iterator I, MachineInstr *M) {
-    return Insts.insertAfter(I.getInstrIterator(), M);
+
+  /// Insert MI into the instruction list after I.
+  iterator insertAfter(iterator I, MachineInstr *MI) {
+    assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
+           "Cannot insert instruction with bundle flags");
+    return Insts.insertAfter(I.getInstrIterator(), MI);
   }
 
   /// Remove an instruction from the instruction list and delete it.
diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index b4ff6b4fcfc..027f777fcf4 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -814,6 +814,18 @@ MachineInstr *MachineBasicBlock::remove_instr(MachineInstr *MI) {
   return Insts.remove(MI);
 }
 
+MachineBasicBlock::instr_iterator
+MachineBasicBlock::insert(instr_iterator I, MachineInstr *MI) {
+  assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
+         "Cannot insert instruction with bundle flags");
+  // Set the bundle flags when inserting inside a bundle.
+  if (I != instr_end() && I->isBundledWithPred()) {
+    MI->setFlag(MachineInstr::BundledPred);
+    MI->setFlag(MachineInstr::BundledSucc);
+  }
+  return Insts.insert(I, MI);
+}
+
 void MachineBasicBlock::splice(MachineBasicBlock::iterator where,
                                MachineBasicBlock *Other,
                                MachineBasicBlock::iterator From) {