From ed185daba7432e9df717f0199336889784b10da3 Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanaka@mips.com>
Date: Thu, 13 Dec 2012 03:17:29 +0000
Subject: [PATCH] [mips] Do not copy GOT address to register $gp if the
 function being called has internal linkage.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170092 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/Mips/MipsISelLowering.cpp    | 13 ++++++++----
 test/CodeGen/Mips/gpreg-lazy-binding.ll | 27 +++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 4 deletions(-)
 create mode 100644 test/CodeGen/Mips/gpreg-lazy-binding.ll

diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index 65b33c12b82..f9a4d4acff4 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -2849,12 +2849,14 @@ MipsTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   // direct call is) turn it into a TargetGlobalAddress/TargetExternalSymbol
   // node so that legalize doesn't hack it.
   bool IsPICCall = (IsN64 || IsPIC); // true if calls are translated to jalr $25
-  bool GlobalOrExternal = false;
+  bool GlobalOrExternal = false, InternalLinkage = false;
   SDValue CalleeLo;
 
   if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
     if (IsPICCall) {
-      if (G->getGlobal()->hasInternalLinkage())
+      InternalLinkage = G->getGlobal()->hasInternalLinkage();
+
+      if (InternalLinkage)
         Callee = getAddrLocal(Callee, DAG, HasMips64);
       else if (LargeGOT)
         Callee = getAddrGlobalLargeGOT(Callee, DAG, MipsII::MO_CALL_HI16,
@@ -2901,8 +2903,11 @@ MipsTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   }
 
   // Insert node "GP copy globalreg" before call to function.
-  // Lazy-binding stubs require GP to point to the GOT.
-  if (IsPICCall) {
+  //
+  // R_MIPS_CALL* operators (emitted when non-internal functions are called
+  // in PIC mode) allow symbols to be resolved via lazy binding.
+  // The lazy binding stub requires GP to point to the GOT.
+  if (IsPICCall && !InternalLinkage) {
     unsigned GPReg = IsN64 ? Mips::GP_64 : Mips::GP;
     EVT Ty = IsN64 ? MVT::i64 : MVT::i32;
     RegsToPass.push_back(std::make_pair(GPReg, GetGlobalReg(DAG, Ty)));
diff --git a/test/CodeGen/Mips/gpreg-lazy-binding.ll b/test/CodeGen/Mips/gpreg-lazy-binding.ll
new file mode 100644
index 00000000000..85d8d4b1db1
--- /dev/null
+++ b/test/CodeGen/Mips/gpreg-lazy-binding.ll
@@ -0,0 +1,27 @@
+; RUN: llc -march=mipsel -disable-mips-delay-filler < %s | FileCheck %s 
+
+@g = external global i32
+
+; CHECK:     addu  $gp
+; CHECK:     jalr  $25
+; CHECK:     nop
+; CHECK-NOT: addu  $gp
+; CHECK:     jalr  $25
+
+define void @f0() nounwind {
+entry:
+  tail call void @externalFunc() nounwind
+  tail call fastcc void @internalFunc()
+  ret void
+}
+
+declare void @externalFunc()
+
+define internal fastcc void @internalFunc() nounwind noinline {
+entry:
+  %0 = load i32* @g, align 4
+  %inc = add nsw i32 %0, 1
+  store i32 %inc, i32* @g, align 4
+  ret void
+}
+
-- 
2.34.1