[mips] Make sure loads from lazy-binding entries do not get CSE'd or hoisted out

of loops.

Previously, two consecutive calls to function "func" would result in the
following sequence of instructions:

1. load $16, %got(func)($gp) // load address of lazy-binding stub.
2. move $25, $16
3. jalr $25                  // jump to lazy-binding stub.
4. nop
5. move $25, $16
6. jalr $25                  // jump to lazy-binding stub again.

With this patch, the second call directly jumps to func's address, bypassing
the lazy-binding resolution routine:

1. load $25, %got(func)($gp) // load address of lazy-binding stub.
2. jalr $25                  // jump to lazy-binding stub.
3. nop
4. load $25, %got(func)($gp) // load resolved address of func.
5. jalr $25                  // directly jump to func.

llvm-svn: 191591

1 files changed, 18 insertions, 8 deletions

diff --git a/llvm/lib/Target/Mips/MipsISelLowering.cpp b/llvm/lib/Target/Mips/MipsISelLowering.cpp
index 5aab3f8dd2f..3eb2dfb6d67 100644
--- a/llvm/lib/Target/Mips/MipsISelLowering.cpp
+++ b/llvm/lib/Target/Mips/MipsISelLowering.cpp
@@ -1468,10 +1468,12 @@ SDValue MipsTargetLowering::lowerGlobalAddress(SDValue Op,
 
   if (LargeGOT)
     return getAddrGlobalLargeGOT(N, Ty, DAG, MipsII::MO_GOT_HI16,
-                                 MipsII::MO_GOT_LO16);
+                                 MipsII::MO_GOT_LO16, DAG.getEntryNode(),
+                                 MachinePointerInfo::getGOT());
 
   return getAddrGlobal(N, Ty, DAG,
-                       HasMips64 ? MipsII::MO_GOT_DISP : MipsII::MO_GOT16);
+                       HasMips64 ? MipsII::MO_GOT_DISP : MipsII::MO_GOT16,
+                       DAG.getEntryNode(), MachinePointerInfo::getGOT());
 }
 
 SDValue MipsTargetLowering::lowerBlockAddress(SDValue Op,
@@ -2313,6 +2315,7 @@ MipsTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   MachineFunction &MF = DAG.getMachineFunction();
   MachineFrameInfo *MFI = MF.getFrameInfo();
   const TargetFrameLowering *TFL = MF.getTarget().getFrameLowering();
+  MipsFunctionInfo *FuncInfo = MF.getInfo<MipsFunctionInfo>();
   bool IsPIC = getTargetMachine().getRelocationModel() == Reloc::PIC_;
 
   // Analyze operands of the call, assigning locations to each operand.
@@ -2446,29 +2449,36 @@ MipsTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
 
   if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
     if (IsPICCall) {
-      InternalLinkage = G->getGlobal()->hasInternalLinkage();
+      const GlobalValue *Val = G->getGlobal();
+      InternalLinkage = Val->hasInternalLinkage();
 
       if (InternalLinkage)
         Callee = getAddrLocal(G, Ty, DAG, HasMips64);
       else if (LargeGOT)
         Callee = getAddrGlobalLargeGOT(G, Ty, DAG, MipsII::MO_CALL_HI16,
-                                       MipsII::MO_CALL_LO16);
+                                       MipsII::MO_CALL_LO16, Chain,
+                                       FuncInfo->callPtrInfo(Val));
       else
-        Callee = getAddrGlobal(G, Ty, DAG, MipsII::MO_GOT_CALL);
+        Callee = getAddrGlobal(G, Ty, DAG, MipsII::MO_GOT_CALL, Chain,
+                               FuncInfo->callPtrInfo(Val));
     } else
       Callee = DAG.getTargetGlobalAddress(G->getGlobal(), DL, getPointerTy(), 0,
                                           MipsII::MO_NO_FLAG);
     GlobalOrExternal = true;
   }
   else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee)) {
+    const char *Sym = S->getSymbol();
+
     if (!IsN64 && !IsPIC) // !N64 && static
-      Callee = DAG.getTargetExternalSymbol(S->getSymbol(), getPointerTy(),
+      Callee = DAG.getTargetExternalSymbol(Sym, getPointerTy(),
                                             MipsII::MO_NO_FLAG);
     else if (LargeGOT)
       Callee = getAddrGlobalLargeGOT(S, Ty, DAG, MipsII::MO_CALL_HI16,
-                                     MipsII::MO_CALL_LO16);
+                                     MipsII::MO_CALL_LO16, Chain,
+                                     FuncInfo->callPtrInfo(Sym));
     else // N64 || PIC
-      Callee = getAddrGlobal(S, Ty, DAG, MipsII::MO_GOT_CALL);
+      Callee = getAddrGlobal(S, Ty, DAG, MipsII::MO_GOT_CALL, Chain,
+                             FuncInfo->callPtrInfo(Sym));
 
     GlobalOrExternal = true;
   }