commit fc1675eb16785cebe4286af15d7853ec09854e0b
author Diana Picus <diana.picus@linaro.org> Wed Jul 05 12:57:24 2017 +0000
committer Diana Picus <diana.picus@linaro.org> Wed Jul 05 12:57:24 2017 +0000
tree 92f3f70d84c7e59b6e805a1ed3d991f9a64611ca
parent 6d14fdf62da34df9e65669a00745d597cfb882df

[GlobalISel] Refactor Legalizer helpers for libcalls

We used to have a helper that replaced an instruction with a libcall.
That turns out to be too aggressive, since sometimes we need to replace
the instruction with at least two libcalls. Therefore, change our
existing helper to only create the libcall and leave the instruction
removal as a separate step. Also rename the helper accordingly.

llvm-svn: 307149

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 84b0a0a..6b3c524 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -99,23 +99,17 @@
   llvm_unreachable("Unknown libcall function");
 }
 
-LegalizerHelper::LegalizeResult llvm::replaceWithLibcall(
-    MachineInstr &MI, MachineIRBuilder &MIRBuilder, RTLIB::Libcall Libcall,
-    const CallLowering::ArgInfo &Result, ArrayRef<CallLowering::ArgInfo> Args) {
+LegalizerHelper::LegalizeResult
+llvm::createLibcall(MachineIRBuilder &MIRBuilder, RTLIB::Libcall Libcall,
+                    const CallLowering::ArgInfo &Result,
+                    ArrayRef<CallLowering::ArgInfo> Args) {
   auto &CLI = *MIRBuilder.getMF().getSubtarget().getCallLowering();
   auto &TLI = *MIRBuilder.getMF().getSubtarget().getTargetLowering();
   const char *Name = TLI.getLibcallName(Libcall);
   MIRBuilder.getMF().getFrameInfo().setHasCalls(true);
-  MIRBuilder.setInstr(MI);
   if (!CLI.lowerCall(MIRBuilder, TLI.getLibcallCallingConv(Libcall),
                      MachineOperand::CreateES(Name), Result, Args))
     return LegalizerHelper::UnableToLegalize;
-
-  // We're about to remove MI, so move the insert point after it.
-  MIRBuilder.setInsertPt(MIRBuilder.getMBB(),
-                         std::next(MIRBuilder.getInsertPt()));
-
-  MI.eraseFromParent();
   return LegalizerHelper::Legalized;
 }
 
@@ -123,10 +117,9 @@
 simpleLibcall(MachineInstr &MI, MachineIRBuilder &MIRBuilder, unsigned Size,
               Type *OpType) {
   auto Libcall = getRTLibDesc(MI.getOpcode(), Size);
-  return replaceWithLibcall(MI, MIRBuilder, Libcall,
-                            {MI.getOperand(0).getReg(), OpType},
-                            {{MI.getOperand(1).getReg(), OpType},
-                             {MI.getOperand(2).getReg(), OpType}});
+  return createLibcall(MIRBuilder, Libcall, {MI.getOperand(0).getReg(), OpType},
+                       {{MI.getOperand(1).getReg(), OpType},
+                        {MI.getOperand(2).getReg(), OpType}});
 }
 
 LegalizerHelper::LegalizeResult
@@ -135,6 +128,8 @@
   unsigned Size = LLTy.getSizeInBits();
   auto &Ctx = MIRBuilder.getMF().getFunction()->getContext();
 
+  MIRBuilder.setInstr(MI);
+
   switch (MI.getOpcode()) {
   default:
     return UnableToLegalize;
@@ -143,15 +138,24 @@
   case TargetOpcode::G_SREM:
   case TargetOpcode::G_UREM: {
     Type *HLTy = Type::getInt32Ty(Ctx);
-    return simpleLibcall(MI, MIRBuilder, Size, HLTy);
+    auto Status = simpleLibcall(MI, MIRBuilder, Size, HLTy);
+    if (Status != Legalized)
+      return Status;
+    break;
   }
   case TargetOpcode::G_FADD:
   case TargetOpcode::G_FPOW:
   case TargetOpcode::G_FREM: {
     Type *HLTy = Size == 64 ? Type::getDoubleTy(Ctx) : Type::getFloatTy(Ctx);
-    return simpleLibcall(MI, MIRBuilder, Size, HLTy);
+    auto Status = simpleLibcall(MI, MIRBuilder, Size, HLTy);
+    if (Status != Legalized)
+      return Status;
+    break;
   }
   }
+
+  MI.eraseFromParent();
+  return Legalized;
 }
 
 LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,