From d71cebf57591e2dc27930d3002848dddc76c3f92 Mon Sep 17 00:00:00 2001
From: Bruno Cardoso Lopes <bruno.cardoso@gmail.com>
Date: Wed, 25 Nov 2009 12:17:58 +0000
Subject: [PATCH] Support PIC loading of constant pool entries

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89863 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/Mips/MipsISelDAGToDAG.cpp        | 17 ++++++++---------
 lib/Target/Mips/MipsISelLowering.cpp        | 16 ++++++++++++----
 test/CodeGen/Mips/2009-11-16-CstPoolLoad.ll |  2 +-
 3 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/lib/Target/Mips/MipsISelDAGToDAG.cpp b/lib/Target/Mips/MipsISelDAGToDAG.cpp
index 43c3b70ceb7..ede111d5090 100644
--- a/lib/Target/Mips/MipsISelDAGToDAG.cpp
+++ b/lib/Target/Mips/MipsISelDAGToDAG.cpp
@@ -144,6 +144,7 @@ SelectAddr(SDValue Op, SDValue Addr, SDValue &Offset, SDValue &Base)
   // on PIC code Load GA
   if (TM.getRelocationModel() == Reloc::PIC_) {
     if ((Addr.getOpcode() == ISD::TargetGlobalAddress) || 
+        (Addr.getOpcode() == ISD::TargetConstantPool) || 
         (Addr.getOpcode() == ISD::TargetJumpTable)){
       Base   = CurDAG->getRegister(Mips::GP, MVT::i32);
       Offset = Addr;
@@ -174,23 +175,21 @@ SelectAddr(SDValue Op, SDValue Addr, SDValue &Offset, SDValue &Base)
     }
 
     // When loading from constant pools, load the lower address part in
-    // the instruction itself. Instead of:
+    // the instruction itself. Example, instead of:
     //  lui $2, %hi($CPI1_0)
     //  addiu $2, $2, %lo($CPI1_0)
     //  lwc1 $f0, 0($2)
     // Generate:
     //  lui $2, %hi($CPI1_0)
     //  lwc1 $f0, %lo($CPI1_0)($2)
-    if (Addr.getOperand(0).getOpcode() == MipsISD::Hi &&
+    if ((Addr.getOperand(0).getOpcode() == MipsISD::Hi || 
+         Addr.getOperand(0).getOpcode() == ISD::LOAD) &&
         Addr.getOperand(1).getOpcode() == MipsISD::Lo) {
       SDValue LoVal = Addr.getOperand(1); 
-      if (ConstantPoolSDNode *CP = dyn_cast<ConstantPoolSDNode>(
-          LoVal.getOperand(0))) {
-        if (!CP->getOffset()) {
-          Base = Addr.getOperand(0);
-          Offset = LoVal.getOperand(0);
-          return true;
-        }
+      if (dyn_cast<ConstantPoolSDNode>(LoVal.getOperand(0))) {
+        Base = Addr.getOperand(0);
+        Offset = LoVal.getOperand(0);
+        return true;
       }
     }
   }
diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index 3fc2ed8adf0..ced8b939336 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -563,8 +563,6 @@ LowerConstantPool(SDValue Op, SelectionDAG &DAG)
   SDValue ResNode;
   ConstantPoolSDNode *N = cast<ConstantPoolSDNode>(Op);
   Constant *C = N->getConstVal();
-  SDValue CP = DAG.getTargetConstantPool(C, MVT::i32, N->getAlignment(), 
-                                         N->getOffset(), MipsII::MO_ABS_HILO);
   // FIXME there isn't actually debug info here
   DebugLoc dl = Op.getDebugLoc();
 
@@ -577,11 +575,21 @@ LowerConstantPool(SDValue Op, SelectionDAG &DAG)
   //  SDValue GPRelNode = DAG.getNode(MipsISD::GPRel, MVT::i32, CP);
   //  SDValue GOT = DAG.getGLOBAL_OFFSET_TABLE(MVT::i32);
   //  ResNode = DAG.getNode(ISD::ADD, MVT::i32, GOT, GPRelNode); 
-  //} else { // %hi/%lo relocation
+
+  if (getTargetMachine().getRelocationModel() != Reloc::PIC_) {
+    SDValue CP = DAG.getTargetConstantPool(C, MVT::i32, N->getAlignment(), 
+                                      N->getOffset(), MipsII::MO_ABS_HILO);
     SDValue HiPart = DAG.getNode(MipsISD::Hi, dl, MVT::i32, CP);
     SDValue Lo = DAG.getNode(MipsISD::Lo, dl, MVT::i32, CP);
     ResNode = DAG.getNode(ISD::ADD, dl, MVT::i32, HiPart, Lo);
-  //}
+  } else {
+    SDValue CP = DAG.getTargetConstantPool(C, MVT::i32, N->getAlignment(), 
+                                      N->getOffset(), MipsII::MO_GOT);
+    SDValue Load = DAG.getLoad(MVT::i32, dl, DAG.getEntryNode(), 
+                                 CP, NULL, 0);
+    SDValue Lo = DAG.getNode(MipsISD::Lo, dl, MVT::i32, CP);
+    ResNode = DAG.getNode(ISD::ADD, dl, MVT::i32, Load, Lo);
+  }
 
   return ResNode;
 }
diff --git a/test/CodeGen/Mips/2009-11-16-CstPoolLoad.ll b/test/CodeGen/Mips/2009-11-16-CstPoolLoad.ll
index f59639f66ad..636b318014a 100644
--- a/test/CodeGen/Mips/2009-11-16-CstPoolLoad.ll
+++ b/test/CodeGen/Mips/2009-11-16-CstPoolLoad.ll
@@ -4,7 +4,7 @@ target triple = "mips-unknown-linux"
 
 define float @h() nounwind readnone {
 entry:
-; CHECK: lui $2, %hi($CPI1_0)
+; CHECK: lw $2, %got($CPI1_0)($gp)
 ; CHECK: lwc1 $f0, %lo($CPI1_0)($2)
   ret float 0x400B333340000000
 }
-- 
2.34.1