From 7a59b1cf90b50bdf3ddf6ea8f69b8f70097d75d6 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Tue, 30 Aug 2005 01:57:02 +0000
Subject: [PATCH] Make sure the selector emits register register copies with
 flag operands linking them to calls when appropriate, this prevents the
 scheduler from pulling these copies away from the call.

This fixes Ptrdist/yacr2

llvm-svn: 23143
---
 llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp | 30 ++++++++++++++-------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index f2d65697da7a..06f363601a42 100644
--- a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -1512,6 +1512,8 @@ SDOperand PPC32DAGToDAGISel::Select(SDOperand Op) {
       PPC::F8, PPC::F9, PPC::F10, PPC::F11, PPC::F12, PPC::F13
     };
     
+    SDOperand InFlag;  // Null incoming flag value.
+    
     for (unsigned i = 2, e = N->getNumOperands(); i != e; ++i) {
       unsigned DestReg = 0;
       MVT::ValueType RegTy;
@@ -1528,17 +1530,21 @@ SDOperand PPC32DAGToDAGISel::Select(SDOperand Op) {
       }
 
       if (N->getOperand(i).getOpcode() != ISD::UNDEF) {
-        SDOperand Reg = CurDAG->getRegister(DestReg, RegTy);
-        Chain = CurDAG->getNode(ISD::CopyToReg, MVT::Other, Chain, Reg,
-                                Select(N->getOperand(i)));
-        CallOperands.push_back(Reg);
+        Chain = CurDAG->getCopyToReg(Chain, DestReg,
+                                     Select(N->getOperand(i)), InFlag);
+        InFlag = Chain.getValue(1);
+        CallOperands.push_back(CurDAG->getRegister(DestReg, RegTy));
       }
     }
 
     // Finally, once everything is in registers to pass to the call, emit the
     // call itself.
-    CallOperands.push_back(Chain);
-    Chain = CurDAG->getTargetNode(CallOpcode, MVT::Other, CallOperands);
+    if (InFlag.Val)
+      CallOperands.push_back(InFlag);   // Strong dep on register copies.
+    else
+      CallOperands.push_back(Chain);    // Weak dep on whatever occurs before
+    Chain = CurDAG->getTargetNode(CallOpcode, MVT::Other, MVT::Flag,
+                                  CallOperands);
     
     std::vector<SDOperand> CallResults;
     
@@ -1548,18 +1554,22 @@ SDOperand PPC32DAGToDAGISel::Select(SDOperand Op) {
     case MVT::Other: break;
     case MVT::i32:
       if (N->getValueType(1) == MVT::i32) {
-        Chain = CurDAG->getCopyFromReg(Chain, PPC::R4, MVT::i32).getValue(1);
+        Chain = CurDAG->getCopyFromReg(Chain, PPC::R4, MVT::i32, 
+                                       Chain.getValue(1)).getValue(1);
         CallResults.push_back(Chain.getValue(0));
-        Chain = CurDAG->getCopyFromReg(Chain, PPC::R3, MVT::i32).getValue(1);
+        Chain = CurDAG->getCopyFromReg(Chain, PPC::R3, MVT::i32,
+                                       Chain.getValue(1)).getValue(1);
         CallResults.push_back(Chain.getValue(0));
       } else {
-        Chain = CurDAG->getCopyFromReg(Chain, PPC::R3, MVT::i32).getValue(1);
+        Chain = CurDAG->getCopyFromReg(Chain, PPC::R3, MVT::i32,
+                                       Chain.getValue(1)).getValue(1);
         CallResults.push_back(Chain.getValue(0));
       }
       break;
     case MVT::f32:
     case MVT::f64:
-      Chain = CurDAG->getCopyFromReg(Chain, PPC::F1, MVT::f64).getValue(1);
+      Chain = CurDAG->getCopyFromReg(Chain, PPC::F1, MVT::f64,
+                                     Chain.getValue(1)).getValue(1);
       if (N->getValueType(0) == MVT::f64)
         CallResults.push_back(Chain.getValue(0));
       else