From ff110265753c19daf0468ee1facf357460497b7e Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Wed, 26 Sep 2007 21:31:07 +0000
Subject: [PATCH] - Added MRegisterInfo::getCrossCopyRegClass() hook. For
 register classes where reg to reg copies are not possible, this returns
 another register class which registers in the specified register class can be
 copied to (and copy back from). - X86 copyRegToReg() now supports copying
 between EFLAGS and GR32 / GR64 registers.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42372 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Target/MRegisterInfo.h | 13 +++++++++++++
 lib/Target/X86/X86RegisterInfo.cpp  | 30 +++++++++++++++++++++++++++++
 lib/Target/X86/X86RegisterInfo.h    |  3 +++
 3 files changed, 46 insertions(+)

diff --git a/include/llvm/Target/MRegisterInfo.h b/include/llvm/Target/MRegisterInfo.h
index 14ed6948e97..bc58080a5ec 100644
--- a/include/llvm/Target/MRegisterInfo.h
+++ b/include/llvm/Target/MRegisterInfo.h
@@ -315,6 +315,11 @@ public:
     return Reg >= FirstVirtualRegister;
   }
 
+  /// getPhysicalRegisterRegClass - Returns the Register Class of a physical
+  /// register of the given type.
+  const TargetRegisterClass *getPhysicalRegisterRegClass(MVT::ValueType VT,
+                                                         unsigned Reg) const;
+
   /// getAllocatableSet - Returns a bitset indexed by register number
   /// indicating if a register is allocatable or not. If a register class is
   /// specified, returns the subset for the class.
@@ -509,6 +514,14 @@ public:
                             const TargetRegisterClass *DestRC,
                             const TargetRegisterClass *SrcRC) const = 0;
 
+  /// getCrossCopyRegClass - Returns a legal register class to copy a register
+  /// in the specified class to or from. Returns NULL if it is possible to copy
+  /// between a two registers of the specified class.
+  virtual const TargetRegisterClass *
+  getCrossCopyRegClass(const TargetRegisterClass *RC) const {
+    return NULL;
+  }
+
   /// reMaterialize - Re-issue the specified 'original' instruction at the
   /// specific location targeting a new destination register.
   virtual void reMaterialize(MachineBasicBlock &MBB,
diff --git a/lib/Target/X86/X86RegisterInfo.cpp b/lib/Target/X86/X86RegisterInfo.cpp
index 98955a305ed..fdb259cd0e6 100644
--- a/lib/Target/X86/X86RegisterInfo.cpp
+++ b/lib/Target/X86/X86RegisterInfo.cpp
@@ -234,6 +234,30 @@ void X86RegisterInfo::copyRegToReg(MachineBasicBlock &MBB,
                                    const TargetRegisterClass *DestRC,
                                    const TargetRegisterClass *SrcRC) const {
   if (DestRC != SrcRC) {
+    // Moving EFLAGS to / from another register requires a push and a pop.
+    if (SrcRC == &X86::CCRRegClass) {
+      assert(SrcReg == X86::EFLAGS);
+      if (DestRC == &X86::GR64RegClass) {
+        BuildMI(MBB, MI, TII.get(X86::PUSHFQ));
+        BuildMI(MBB, MI, TII.get(X86::POP64r), DestReg);
+        return;
+      } else if (DestRC == &X86::GR32RegClass) {
+        BuildMI(MBB, MI, TII.get(X86::PUSHFD));
+        BuildMI(MBB, MI, TII.get(X86::POP32r), DestReg);
+        return;
+      }
+    } else if (DestRC == &X86::CCRRegClass) {
+      assert(DestReg == X86::EFLAGS);
+      if (SrcRC == &X86::GR64RegClass) {
+        BuildMI(MBB, MI, TII.get(X86::PUSH64r)).addReg(SrcReg);
+        BuildMI(MBB, MI, TII.get(X86::POPFQ));
+        return;
+      } else if (SrcRC == &X86::GR32RegClass) {
+        BuildMI(MBB, MI, TII.get(X86::PUSH32r)).addReg(SrcReg);
+        BuildMI(MBB, MI, TII.get(X86::POPFD));
+        return;
+      }
+    }
     cerr << "Not yet supported!";
     abort();
   }
@@ -272,6 +296,12 @@ void X86RegisterInfo::copyRegToReg(MachineBasicBlock &MBB,
   BuildMI(MBB, MI, TII.get(Opc), DestReg).addReg(SrcReg);
 }
 
+const TargetRegisterClass *
+X86RegisterInfo::getCrossCopyRegClass(const TargetRegisterClass *RC) const {
+  if (RC == &X86::CCRRegClass)
+    return &X86::GR32RegClass;
+  return NULL;
+}
 
 void X86RegisterInfo::reMaterialize(MachineBasicBlock &MBB,
                                     MachineBasicBlock::iterator I,
diff --git a/lib/Target/X86/X86RegisterInfo.h b/lib/Target/X86/X86RegisterInfo.h
index e0d1c6a4bf3..fd26d9fd7d1 100644
--- a/lib/Target/X86/X86RegisterInfo.h
+++ b/lib/Target/X86/X86RegisterInfo.h
@@ -81,6 +81,9 @@ public:
                     const TargetRegisterClass *DestRC,
                     const TargetRegisterClass *SrcRC) const;
  
+  const TargetRegisterClass *
+  getCrossCopyRegClass(const TargetRegisterClass *RC) const;
+
   void reMaterialize(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
                      unsigned DestReg, const MachineInstr *Orig) const;
 
-- 
2.34.1