The local register allocator has to spill dirty callee saved registers before a

call that might throw. The landing pad assumes that all registers are in stack
slots.

We used to spill those dirty CSRs after the call, and the stack slots would be
wrong when arriving at the landing pad.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102770 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 33 insertions, 6 deletions

diff --git a/lib/CodeGen/RegAllocLocal.cpp b/lib/CodeGen/RegAllocLocal.cpp
index 1885fabab8..920ba5732a 100644
--- a/lib/CodeGen/RegAllocLocal.cpp
+++ b/lib/CodeGen/RegAllocLocal.cpp
@@ -189,6 +189,9 @@ namespace {
     ///
     void removePhysReg(unsigned PhysReg);
 
+    void storeVirtReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
+                      unsigned VirtReg, unsigned PhysReg, bool isKill);
+
     /// spillVirtReg - This method spills the value specified by PhysReg into
     /// the virtual register slot specified by VirtReg.  It then updates the RA
     /// data structures to indicate the fact that PhysReg is now available.
@@ -286,6 +289,17 @@ void RALocal::removePhysReg(unsigned PhysReg) {
     PhysRegsUseOrder.erase(It);
 }
 
+/// storeVirtReg - Store a virtual register to its assigned stack slot.
+void RALocal::storeVirtReg(MachineBasicBlock &MBB,
+                           MachineBasicBlock::iterator I,
+                           unsigned VirtReg, unsigned PhysReg,
+                           bool isKill) {
+  const TargetRegisterClass *RC = MF->getRegInfo().getRegClass(VirtReg);
+  int FrameIndex = getStackSpaceFor(VirtReg, RC);
+  DEBUG(dbgs() << " to stack slot #" << FrameIndex);
+  TII->storeRegToStackSlot(MBB, I, PhysReg, isKill, FrameIndex, RC);
+  ++NumStores;   // Update statistics
+}
 
 /// spillVirtReg - This method spills the value specified by PhysReg into the
 /// virtual register slot specified by VirtReg.  It then updates the RA data
@@ -309,15 +323,11 @@ void RALocal::spillVirtReg(MachineBasicBlock &MBB,
     // Otherwise, there is a virtual register corresponding to this physical
     // register.  We only need to spill it into its stack slot if it has been
     // modified.
-    const TargetRegisterClass *RC = MF->getRegInfo().getRegClass(VirtReg);
-    int FrameIndex = getStackSpaceFor(VirtReg, RC);
-    DEBUG(dbgs() << " to stack slot #" << FrameIndex);
     // If the instruction reads the register that's spilled, (e.g. this can
     // happen if it is a move to a physical register), then the spill
     // instruction is not a kill.
     bool isKill = !(I != MBB.end() && I->readsRegister(PhysReg));
-    TII->storeRegToStackSlot(MBB, I, PhysReg, isKill, FrameIndex, RC);
-    ++NumStores;   // Update statistics
+    storeVirtReg(MBB, I, VirtReg, PhysReg, isKill);
   }
 
   getVirt2PhysRegMapSlot(VirtReg) = 0;   // VirtReg no longer available
@@ -801,9 +811,12 @@ void RALocal::AllocateBasicBlock(MachineBasicBlock &MBB) {
         dbgs() << "\nStarting RegAlloc of: " << *MI;
         dbgs() << "  Regs have values: ";
         for (unsigned i = 0; i != TRI->getNumRegs(); ++i)
-          if (PhysRegsUsed[i] != -1 && PhysRegsUsed[i] != -2)
+          if (PhysRegsUsed[i] != -1 && PhysRegsUsed[i] != -2) {
+            if (PhysRegsUsed[i] && isVirtRegModified(PhysRegsUsed[i]))
+              dbgs() << "*";
             dbgs() << "[" << TRI->getName(i)
                    << ",%reg" << PhysRegsUsed[i] << "] ";
+          }
         dbgs() << '\n';
       });
 
@@ -1092,6 +1105,20 @@ void RALocal::AllocateBasicBlock(MachineBasicBlock &MBB) {
       }
     }
     
+    // If this instruction is a call, make sure there are no dirty registers. The
+    // call might throw an exception, and the landing pad expects to find all
+    // registers in stack slots.
+    if (TID.isCall())
+      for (unsigned i = 0, e = TRI->getNumRegs(); i != e; ++i) {
+        if (PhysRegsUsed[i] <= 0) continue;
+        unsigned VirtReg = PhysRegsUsed[i];
+        if (!isVirtRegModified(VirtReg)) continue;
+        DEBUG(dbgs() << "  Storing dirty %reg" << VirtReg);
+        storeVirtReg(MBB, MI, VirtReg, i, false);
+        markVirtRegModified(VirtReg, false);
+        DEBUG(dbgs() << " because the call might throw\n");
+      }
+
     // Finally, if this is a noop copy instruction, zap it.  (Except that if
     // the copy is dead, it must be kept to avoid messing up liveness info for
     // the register scavenger.  See pr4100.)