[PowerPC][AIX] Using milicode for memcmp instead of libcall (#147093)

AIX has "millicode" routines, which are functions loaded at boot time
into fixed addresses in kernel memory. This allows them to be customized
for the processor. The __memcmp routine is a millicode implementation;
we use millicode for the memcmp function instead of a library call to
improve performance.

6 files changed, 52 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index bfa72bf..b9e72c9 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -8889,6 +8889,44 @@ static void checkAddrSpaceIsValidForLibcall(const TargetLowering *TLI,
   }
 }
 
+std::pair<SDValue, SDValue>
+SelectionDAG::getMemcmp(SDValue Chain, const SDLoc &dl, SDValue Mem0,
+                        SDValue Mem1, SDValue Size, const CallInst *CI) {
+  const char *LibCallName = TLI->getLibcallName(RTLIB::MEMCMP);
+  if (!LibCallName)
+    return {};
+
+  // Emit a library call.
+  auto GetEntry = [](Type *Ty, SDValue &SDV) {
+    TargetLowering::ArgListEntry E;
+    E.Ty = Ty;
+    E.Node = SDV;
+    return E;
+  };
+
+  PointerType *PT = PointerType::getUnqual(*getContext());
+  TargetLowering::ArgListTy Args = {
+      GetEntry(PT, Mem0), GetEntry(PT, Mem1),
+      GetEntry(getDataLayout().getIntPtrType(*getContext()), Size)};
+
+  TargetLowering::CallLoweringInfo CLI(*this);
+  bool IsTailCall = false;
+  bool ReturnsFirstArg = CI && funcReturnsFirstArgOfCall(*CI);
+  IsTailCall = CI && CI->isTailCall() &&
+               isInTailCallPosition(*CI, getTarget(), ReturnsFirstArg);
+
+  CLI.setDebugLoc(dl)
+      .setChain(Chain)
+      .setLibCallee(
+          TLI->getLibcallCallingConv(RTLIB::MEMCMP),
+          Type::getInt32Ty(*getContext()),
+          getExternalSymbol(LibCallName, TLI->getPointerTy(getDataLayout())),
+          std::move(Args))
+      .setTailCall(IsTailCall);
+
+  return TLI->LowerCallTo(CLI);
+}
+
 SDValue SelectionDAG::getMemcpy(
     SDValue Chain, const SDLoc &dl, SDValue Dst, SDValue Src, SDValue Size,
     Align Alignment, bool isVol, bool AlwaysInline, const CallInst *CI,
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 868e2f4..f5f5c14 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -9090,7 +9090,7 @@ bool SelectionDAGBuilder::visitMemCmpBCmpCall(const CallInst &I) {
   const SelectionDAGTargetInfo &TSI = DAG.getSelectionDAGInfo();
   std::pair<SDValue, SDValue> Res = TSI.EmitTargetCodeForMemcmp(
       DAG, getCurSDLoc(), DAG.getRoot(), getValue(LHS), getValue(RHS),
-      getValue(Size), MachinePointerInfo(LHS), MachinePointerInfo(RHS));
+      getValue(Size), &I);
   if (Res.first.getNode()) {
     processIntegerCallValue(I, Res.first, true);
     PendingLoads.push_back(Res.second);
diff --git a/llvm/lib/Target/PowerPC/PPCSelectionDAGInfo.cpp b/llvm/lib/Target/PowerPC/PPCSelectionDAGInfo.cpp
index 95de9f3..4039fed 100644
--- a/llvm/lib/Target/PowerPC/PPCSelectionDAGInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCSelectionDAGInfo.cpp
@@ -22,3 +22,9 @@ bool PPCSelectionDAGInfo::isTargetStrictFPOpcode(unsigned Opcode) const {
   return Opcode >= PPCISD::FIRST_STRICTFP_OPCODE &&
          Opcode <= PPCISD::LAST_STRICTFP_OPCODE;
 }
+
+std::pair<SDValue, SDValue> PPCSelectionDAGInfo::EmitTargetCodeForMemcmp(
+    SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Op1, SDValue Op2,
+    SDValue Op3, const CallInst *CI) const {
+  return DAG.getMemcmp(Chain, dl, Op1, Op2, Op3, CI);
+}
diff --git a/llvm/lib/Target/PowerPC/PPCSelectionDAGInfo.h b/llvm/lib/Target/PowerPC/PPCSelectionDAGInfo.h
index 08e2ddb..5635c6a 100644
--- a/llvm/lib/Target/PowerPC/PPCSelectionDAGInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCSelectionDAGInfo.h
@@ -20,6 +20,11 @@ public:
   bool isTargetMemoryOpcode(unsigned Opcode) const override;
 
   bool isTargetStrictFPOpcode(unsigned Opcode) const override;
+
+  std::pair<SDValue, SDValue>
+  EmitTargetCodeForMemcmp(SelectionDAG &DAG, const SDLoc &dl, SDValue Chain,
+                          SDValue Op1, SDValue Op2, SDValue Op3,
+                          const CallInst *CI) const;
 };
 
 } // namespace llvm
diff --git a/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp b/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp
index d76babe..afe838a 100644
--- a/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.cpp
@@ -181,8 +181,7 @@ static SDValue addIPMSequence(const SDLoc &DL, SDValue CCReg,
 
 std::pair<SDValue, SDValue> SystemZSelectionDAGInfo::EmitTargetCodeForMemcmp(
     SelectionDAG &DAG, const SDLoc &DL, SDValue Chain, SDValue Src1,
-    SDValue Src2, SDValue Size, MachinePointerInfo Op1PtrInfo,
-    MachinePointerInfo Op2PtrInfo) const {
+    SDValue Src2, SDValue Size, const CallInst *CI) const {
   SDValue CCReg;
   // Swap operands to invert CC == 1 vs. CC == 2 cases.
   if (auto *CSize = dyn_cast<ConstantSDNode>(Size)) {
diff --git a/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.h b/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.h
index c928f34..5a1e0cd 100644
--- a/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.h
+++ b/llvm/lib/Target/SystemZ/SystemZSelectionDAGInfo.h
@@ -41,8 +41,7 @@ public:
   std::pair<SDValue, SDValue>
   EmitTargetCodeForMemcmp(SelectionDAG &DAG, const SDLoc &DL, SDValue Chain,
                           SDValue Src1, SDValue Src2, SDValue Size,
-                          MachinePointerInfo Op1PtrInfo,
-                          MachinePointerInfo Op2PtrInfo) const override;
+                          const CallInst *CI) const override;
 
   std::pair<SDValue, SDValue>
   EmitTargetCodeForMemchr(SelectionDAG &DAG, const SDLoc &DL, SDValue Chain,