Target RegisterInfo: devirtualize TargetFrameLowering

Summary:
The target frame lowering's concrete type is always known in RegisterInfo, yet it's only sometimes devirtualized through a static_cast. This change adds an auto-generated static function <Target>GenRegisterInfo::getFrameLowering(const MachineFunction &MF) which does this devirtualization, and uses this function in all targets which can.

This change was suggested by sunfish in D11070 for WebAssembly, I figure that I may as well improve the other targets while I'm here.

Subscribers: sunfish, ted, llvm-commits, jfb

Differential Revision: http://reviews.llvm.org/D11093

llvm-svn: 241921

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/utils/TableGen/RegisterInfoEmitter.cpp b/llvm/utils/TableGen/RegisterInfoEmitter.cpp
index 7506e91b6f4..9619fb9e356 100644
--- a/llvm/utils/TableGen/RegisterInfoEmitter.cpp
+++ b/llvm/utils/TableGen/RegisterInfoEmitter.cpp
@@ -1070,6 +1070,8 @@ RegisterInfoEmitter::runTargetHeader(raw_ostream &OS, CodeGenTarget &Target,
 
   OS << "namespace llvm {\n\n";
 
+  OS << "class " << TargetName << "FrameLowering;\n\n";
+
   OS << "struct " << ClassName << " : public TargetRegisterInfo {\n"
      << "  explicit " << ClassName
      << "(unsigned RA, unsigned D = 0, unsigned E = 0, unsigned PC = 0);\n"
@@ -1096,6 +1098,9 @@ RegisterInfoEmitter::runTargetHeader(raw_ostream &OS, CodeGenTarget &Target,
      << "unsigned RegUnit) const override;\n"
      << "  ArrayRef<const char *> getRegMaskNames() const override;\n"
      << "  ArrayRef<const uint32_t *> getRegMasks() const override;\n"
+     << "  /// Devirtualized TargetFrameLowering.\n"
+     << "  static const " << TargetName << "FrameLowering *getFrameLowering(\n"
+     << "      const MachineFunction &MF);\n"
      << "};\n\n";
 
   const auto &RegisterClasses = RegBank.getRegClasses();
@@ -1467,6 +1472,13 @@ RegisterInfoEmitter::runTargetDesc(raw_ostream &OS, CodeGenTarget &Target,
      << ");\n";
   OS << "}\n\n";
 
+  OS << "const " << TargetName << "FrameLowering *"
+     << TargetName << "GenRegisterInfo::\n"
+     << "    getFrameLowering(const MachineFunction &MF) {\n"
+     << "  return static_cast<const " << TargetName << "FrameLowering *>(\n"
+     << "      MF.getSubtarget().getFrameLowering());\n"
+     << "}\n\n";
+
   OS << "} // End llvm namespace\n";
   OS << "#endif // GET_REGINFO_TARGET_DESC\n\n";
 }