Add support for updating the LiveIntervals of registers used by 'exotic'

terminators that actually have register uses when splitting critical edges.

This commit also introduces a method repairIntervalsInRange() on LiveIntervals,
which allows for repairing LiveIntervals in a small range after an arbitrary
target hook modifies, inserts, and removes instructions. It's pretty limited
right now, but I hope to extend it to support all of the things that are done
by the convertToThreeAddress() target hooks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175382 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 29 insertions, 0 deletions

diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp
index df1c7c2a66..3d754366ee 100644
--- a/lib/CodeGen/MachineBasicBlock.cpp
+++ b/lib/CodeGen/MachineBasicBlock.cpp
@@ -698,6 +698,24 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
       }
     }
 
+  SmallVector<unsigned, 4> UsedRegs;
+  if (LIS) {
+    for (instr_iterator I = getFirstInstrTerminator(), E = instr_end();
+         I != E; ++I) {
+      MachineInstr *MI = I;
+
+      for (MachineInstr::mop_iterator OI = MI->operands_begin(),
+           OE = MI->operands_end(); OI != OE; ++OI) {
+        if (!OI->isReg() || OI->getReg() == 0)
+          continue;
+
+        unsigned Reg = OI->getReg();
+        if (std::find(UsedRegs.begin(), UsedRegs.end(), Reg) == UsedRegs.end())
+          UsedRegs.push_back(Reg);
+      }
+    }
+  }
+
   ReplaceUsesOfBlockWith(Succ, NMBB);
 
   // If updateTerminator() removes instructions, we need to remove them from
@@ -830,6 +848,17 @@ MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
         LI.removeRange(StartIndex, EndIndex);
       }
     }
+
+    // Update all intervals for registers whose uses may have been modified by
+    // updateTerminator().
+    iterator FirstTerminator = getFirstTerminator();
+    MachineInstr *FirstTerminatorMI = FirstTerminator;
+    if (FirstTerminatorMI->isBundled())
+      FirstTerminatorMI = getBundleStart(FirstTerminatorMI);
+    reverse_iterator PreTerminators =
+      (FirstTerminator == begin()) ? rend()
+                                   : reverse_iterator(FirstTerminatorMI);
+    LIS->repairIntervalsInRange(this, rbegin(), PreTerminators, UsedRegs);
   }
 
   if (MachineDominatorTree *MDT =