From 459a36bd34809ffc5d74de79b3e46f6e02e5184f Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Wed, 4 Aug 2010 18:42:02 +0000
Subject: [PATCH] While spilling live registers at the end of block check
 whether they are used by DBG_VALUE machine instructions or not. If a spilled
 register is used by DBG_VALUE machine instruction then insert a new DBG_VALUE
 machine instruction to encode variable's new location on stack.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110235 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/RegAllocFast.cpp | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/lib/CodeGen/RegAllocFast.cpp b/lib/CodeGen/RegAllocFast.cpp
index 66f83d823e2..9567308aa73 100644
--- a/lib/CodeGen/RegAllocFast.cpp
+++ b/lib/CodeGen/RegAllocFast.cpp
@@ -16,6 +16,7 @@
 #include "llvm/BasicBlock.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/Passes.h"
@@ -80,6 +81,8 @@ namespace {
     // that is currently available in a physical register.
     LiveRegMap LiveVirtRegs;
 
+    DenseMap<unsigned, MachineInstr *> LiveDbgValueMap;
+
     // RegState - Track the state of a physical register.
     enum RegState {
       // A disabled register is not available for allocation, but an alias may
@@ -265,6 +268,24 @@ void RAFast::spillVirtReg(MachineBasicBlock::iterator MI,
     TII->storeRegToStackSlot(*MBB, MI, LR.PhysReg, SpillKill, FI, RC, TRI);
     ++NumStores;   // Update statistics
 
+    // If this register is used by DBG_VALUE then insert new DBG_VALUE to 
+    // identify spilled location as the place to find corresponding variable's
+    // value.
+    if (MachineInstr *DBG = LiveDbgValueMap.lookup(LRI->first)) {
+      const MDNode *MDPtr = 
+        DBG->getOperand(DBG->getNumOperands()-1).getMetadata();
+      int64_t Offset = 0;
+      if (DBG->getOperand(1).isImm())
+        Offset = DBG->getOperand(1).getImm();
+      DebugLoc DL = MI->getDebugLoc();
+      if (MachineInstr *NewDV = 
+          TII->emitFrameIndexDebugValue(*MF, FI, Offset, MDPtr, DL)) {
+        MachineBasicBlock *MBB = DBG->getParent();
+        MBB->insert(MI, NewDV);
+        DEBUG(dbgs() << "Inserting debug info due to spill:" << "\n" << *NewDV);
+        LiveDbgValueMap[LRI->first] = NewDV;
+      }
+    }
     if (SpillKill)
       LR.LastUse = 0; // Don't kill register again
   }
@@ -761,6 +782,7 @@ void RAFast::AllocateBasicBlock() {
           if (!MO.isReg()) continue;
           unsigned Reg = MO.getReg();
           if (!Reg || TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
+          LiveDbgValueMap[Reg] = MI;
           LiveRegMap::iterator LRI = LiveVirtRegs.find(Reg);
           if (LRI != LiveVirtRegs.end())
             setPhysReg(MI, i, LRI->second.PhysReg);
@@ -770,7 +792,7 @@ void RAFast::AllocateBasicBlock() {
               MO.setReg(0); // We can't allocate a physreg for a DebugValue, sorry!
             else {
               // Modify DBG_VALUE now that the value is in a spill slot.
-              uint64_t Offset = MI->getOperand(1).getImm();
+              int64_t Offset = MI->getOperand(1).getImm();
               const MDNode *MDPtr = 
                 MI->getOperand(MI->getNumOperands()-1).getMetadata();
               DebugLoc DL = MI->getDebugLoc();
@@ -1004,6 +1026,7 @@ bool RAFast::runOnMachineFunction(MachineFunction &Fn) {
 
   SkippedInstrs.clear();
   StackSlotForVirtReg.clear();
+  LiveDbgValueMap.clear();
   return true;
 }
 
-- 
2.11.0