Properly handle passing of FP stuff to varargs function on Win64:

value should be copied to the corresponding shadow reg as well.
Patch by Cameron Esfahani!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112262 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 42 insertions, 0 deletions

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 8927afe500..cddf5c6b33 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -2008,6 +2008,19 @@ X86TargetLowering::LowerCall(SDValue Chain, SDValue Callee,
 
     if (VA.isRegLoc()) {
       RegsToPass.push_back(std::make_pair(VA.getLocReg(), Arg));
+      if (isVarArg && Subtarget->isTargetWin64()) {
+        // Win64 ABI requires argument XMM reg to be copied to the corresponding
+        // shadow reg if callee is a varargs function.
+        unsigned ShadowReg = 0;
+        switch (VA.getLocReg()) {
+        case X86::XMM0: ShadowReg = X86::RCX; break;
+        case X86::XMM1: ShadowReg = X86::RDX; break;
+        case X86::XMM2: ShadowReg = X86::R8; break;
+        case X86::XMM3: ShadowReg = X86::R9; break;
+        }
+        if (ShadowReg)
+          RegsToPass.push_back(std::make_pair(ShadowReg, Arg));
+      }
     } else if (!IsSibcall && (!isTailCall || isByVal)) {
       assert(VA.isMemLoc());
       if (StackPtr.getNode() == 0)
diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index 91c45c2f8e..5280940cf4 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -1845,6 +1845,33 @@ static bool isHReg(unsigned Reg) {
   return X86::GR8_ABCD_HRegClass.contains(Reg);
 }
 
+// Try and copy between VR128/VR64 and GR64 registers.
+static unsigned CopyToFromAsymmetricReg(unsigned DestReg, unsigned SrcReg) {
+  // SrcReg(VR128) -> DestReg(GR64)
+  // SrcReg(VR64)  -> DestReg(GR64)
+  // SrcReg(GR64)  -> DestReg(VR128)
+  // SrcReg(GR64)  -> DestReg(VR64)
+
+  if (X86::GR64RegClass.contains(DestReg)) {
+    if (X86::VR128RegClass.contains(SrcReg)) {
+      // Copy from a VR128 register to a GR64 register.
+      return X86::MOVPQIto64rr;
+    } else if (X86::VR64RegClass.contains(SrcReg)) {
+      // Copy from a VR64 register to a GR64 register.
+      return X86::MOVSDto64rr;
+    }
+  } else if (X86::GR64RegClass.contains(SrcReg)) {
+    // Copy from a GR64 register to a VR128 register.
+    if (X86::VR128RegClass.contains(DestReg))
+      return X86::MOV64toPQIrr;
+    // Copy from a GR64 register to a VR64 register.
+    else if (X86::VR64RegClass.contains(DestReg))
+      return X86::MOV64toSDrr;
+  }
+
+  return 0;
+}
+
 void X86InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
                                MachineBasicBlock::iterator MI, DebugLoc DL,
                                unsigned DestReg, unsigned SrcReg,
@@ -1869,6 +1896,8 @@ void X86InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
     Opc = X86::MOVAPSrr;
   else if (X86::VR64RegClass.contains(DestReg, SrcReg))
     Opc = X86::MMX_MOVQ64rr;
+  else
+    Opc = CopyToFromAsymmetricReg(DestReg, SrcReg);
 
   if (Opc) {
     BuildMI(MBB, MI, DL, get(Opc), DestReg)