findDeadCallerSavedReg needs to pay attention to calling convention

Caller saved regs differ between SysV and Win64. Use the tail call available set to scavenge from.

Refactor register info to create new helper to get at tail call GPRs. Added a new test case for windows. Fixed up a number of X64 tests since now RCX is preferred over RDX on SysV.

Differential Revision: http://reviews.llvm.org/D14878

llvm-svn: 253927

4 files changed, 26 insertions, 24 deletions

diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index 4fbe3613d1e..c7f71478f38 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -146,21 +146,14 @@ static unsigned getLEArOpcode(unsigned IsLP64) {
 /// to this register without worry about clobbering it.
 static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB,
                                        MachineBasicBlock::iterator &MBBI,
-                                       const TargetRegisterInfo *TRI,
+                                       const X86RegisterInfo *TRI,
                                        bool Is64Bit) {
   const MachineFunction *MF = MBB.getParent();
   const Function *F = MF->getFunction();
   if (!F || MF->getMMI().callsEHReturn())
     return 0;
 
-  static const uint16_t CallerSavedRegs32Bit[] = {
-    X86::EAX, X86::EDX, X86::ECX, 0
-  };
-
-  static const uint16_t CallerSavedRegs64Bit[] = {
-    X86::RAX, X86::RDX, X86::RCX, X86::RSI, X86::RDI,
-    X86::R8,  X86::R9,  X86::R10, X86::R11, 0
-  };
+  const TargetRegisterClass &AvailableRegs = *TRI->getGPRsForTailCall(*MF);
 
   unsigned Opc = MBBI->getOpcode();
   switch (Opc) {
@@ -189,10 +182,9 @@ static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB,
         Uses.insert(*AI);
     }
 
-    const uint16_t *CS = Is64Bit ? CallerSavedRegs64Bit : CallerSavedRegs32Bit;
-    for (; *CS; ++CS)
-      if (!Uses.count(*CS))
-        return *CS;
+    for (auto CS : AvailableRegs)
+      if (!Uses.count(CS) && CS != X86::RIP)
+        return CS;
   }
   }
 
diff --git a/llvm/lib/Target/X86/X86RegisterInfo.cpp b/llvm/lib/Target/X86/X86RegisterInfo.cpp
index 8b4bbac7007..39de5004143 100644
--- a/llvm/lib/Target/X86/X86RegisterInfo.cpp
+++ b/llvm/lib/Target/X86/X86RegisterInfo.cpp
@@ -177,20 +177,25 @@ X86RegisterInfo::getPointerRegClass(const MachineFunction &MF,
       return &X86::GR64_NOREX_NOSPRegClass;
     return &X86::GR32_NOREX_NOSPRegClass;
   case 4: // Available for tailcall (not callee-saved GPRs).
-    const Function *F = MF.getFunction();
-    if (IsWin64 || (F && F->getCallingConv() == CallingConv::X86_64_Win64))
-      return &X86::GR64_TCW64RegClass;
-    else if (Is64Bit)
-      return &X86::GR64_TCRegClass;
-
-    bool hasHipeCC = (F ? F->getCallingConv() == CallingConv::HiPE : false);
-    if (hasHipeCC)
-      return &X86::GR32RegClass;
-    return &X86::GR32_TCRegClass;
+    return getGPRsForTailCall(MF);
   }
 }
 
 const TargetRegisterClass *
+X86RegisterInfo::getGPRsForTailCall(const MachineFunction &MF) const {
+  const Function *F = MF.getFunction();
+  if (IsWin64 || (F && F->getCallingConv() == CallingConv::X86_64_Win64))
+    return &X86::GR64_TCW64RegClass;
+  else if (Is64Bit)
+    return &X86::GR64_TCRegClass;
+
+  bool hasHipeCC = (F ? F->getCallingConv() == CallingConv::HiPE : false);
+  if (hasHipeCC)
+    return &X86::GR32RegClass;
+  return &X86::GR32_TCRegClass;
+}
+
+const TargetRegisterClass *
 X86RegisterInfo::getCrossCopyRegClass(const TargetRegisterClass *RC) const {
   if (RC == &X86::CCRRegClass) {
     if (Is64Bit)
diff --git a/llvm/lib/Target/X86/X86RegisterInfo.h b/llvm/lib/Target/X86/X86RegisterInfo.h
index 1b1a1ccfc1a..c3a2845c362 100644
--- a/llvm/lib/Target/X86/X86RegisterInfo.h
+++ b/llvm/lib/Target/X86/X86RegisterInfo.h
@@ -87,6 +87,11 @@ public:
   const TargetRegisterClass *
   getCrossCopyRegClass(const TargetRegisterClass *RC) const override;
 
+  /// getGPRsForTailCall - Returns a register class with registers that can be
+  /// used in forming tail calls.
+  const TargetRegisterClass *
+  getGPRsForTailCall(const MachineFunction &MF) const;
+
   unsigned getRegPressureLimit(const TargetRegisterClass *RC,
                                MachineFunction &MF) const override;
 
diff --git a/llvm/lib/Target/X86/X86RegisterInfo.td b/llvm/lib/Target/X86/X86RegisterInfo.td
index 6c74dcbff5b..12f38c7946a 100644
--- a/llvm/lib/Target/X86/X86RegisterInfo.td
+++ b/llvm/lib/Target/X86/X86RegisterInfo.td
@@ -375,7 +375,7 @@ def GR32_TC   : RegisterClass<"X86", [i32], 32, (add EAX, ECX, EDX)>;
 def GR64_TC   : RegisterClass<"X86", [i64], 64, (add RAX, RCX, RDX, RSI, RDI,
                                                      R8, R9, R11, RIP)>;
 def GR64_TCW64 : RegisterClass<"X86", [i64], 64, (add RAX, RCX, RDX,
-                                                      R8, R9, R11)>;
+                                                      R8, R9, R10, R11)>;
 
 // GR8_NOREX - GR8 registers which do not require a REX prefix.
 def GR8_NOREX : RegisterClass<"X86", [i8], 8,