Replace r102368 with code that's less fragile. This creates DBG_VALUE instructions for function arguments early and insert them after instruction selection is done.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102554 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 19 insertions, 5 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 2cdd1cc978..adb321d929 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -212,14 +212,28 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
 
   SelectAllBasicBlocks(Fn);
 
-  // Release function-specific state. SDB and CurDAG are already cleared
-  // at this point.
-  FuncInfo->clear();
-
   // If the first basic block in the function has live ins that need to be
   // copied into vregs, emit the copies into the top of the block before
   // emitting the code for the block.
-  RegInfo->EmitLiveInCopies(MF->begin(), TRI, TII);
+  MachineBasicBlock *EntryMBB = MF->begin();
+  RegInfo->EmitLiveInCopies(EntryMBB, TRI, TII);
+
+  // Insert DBG_VALUE instructions for function arguments to the entry block.
+  for (unsigned i = 0, e = FuncInfo->ArgDbgValues.size(); i != e; ++i) {
+    MachineInstr *MI = FuncInfo->ArgDbgValues[e-i-1];
+    unsigned Reg = MI->getOperand(0).getReg();
+    if (TargetRegisterInfo::isPhysicalRegister(Reg))
+      EntryMBB->insert(EntryMBB->begin(), MI);
+    else {
+      MachineInstr *Def = RegInfo->getVRegDef(Reg);
+      MachineBasicBlock::iterator InsertPos = Def;
+      EntryMBB->insert(llvm::next(InsertPos), MI);
+    }
+  }
+
+  // Release function-specific state. SDB and CurDAG are already cleared
+  // at this point.
+  FuncInfo->clear();
 
   return true;
 }