[SystemZ] Use upper words of GR64s for codegen

This just adds the basics necessary for allocating the upper words to
virtual registers (move, load and store).  The move support is parameterised
in a way that makes it easy to handle zero extensions, but the associated
zero-extend patterns are added by a later patch.

The easiest way of testing this seemed to be add a new "h" register
constraint for high words.  I don't expect the constraint to be useful
in real inline asms, but it should work, so I didn't try to hide it
behind an option.

llvm-svn: 191739

1 files changed, 10 insertions, 2 deletions

diff --git a/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp b/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
index 21653e85e1c..cb0f445cf74 100644
--- a/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
@@ -51,7 +51,10 @@ SystemZTargetLowering::SystemZTargetLowering(SystemZTargetMachine &tm)
   MVT PtrVT = getPointerTy();
 
   // Set up the register classes.
-  addRegisterClass(MVT::i32,  &SystemZ::GR32BitRegClass);
+  if (Subtarget.hasHighWord())
+    addRegisterClass(MVT::i32, &SystemZ::GRX32BitRegClass);
+  else
+    addRegisterClass(MVT::i32, &SystemZ::GR32BitRegClass);
   addRegisterClass(MVT::i64,  &SystemZ::GR64BitRegClass);
   addRegisterClass(MVT::f32,  &SystemZ::FP32BitRegClass);
   addRegisterClass(MVT::f64,  &SystemZ::FP64BitRegClass);
@@ -338,6 +341,7 @@ SystemZTargetLowering::getConstraintType(const std::string &Constraint) const {
     case 'a': // Address register
     case 'd': // Data register (equivalent to 'r')
     case 'f': // Floating-point register
+    case 'h': // High-part register
     case 'r': // General-purpose register
       return C_RegisterClass;
 
@@ -380,6 +384,7 @@ getSingleConstraintMatchWeight(AsmOperandInfo &info,
 
   case 'a': // Address register
   case 'd': // Data register (equivalent to 'r')
+  case 'h': // High-part register
   case 'r': // General-purpose register
     if (CallOperandVal->getType()->isIntegerTy())
       weight = CW_Register;
@@ -460,6 +465,9 @@ getRegForInlineAsmConstraint(const std::string &Constraint, MVT VT) const {
         return std::make_pair(0U, &SystemZ::ADDR128BitRegClass);
       return std::make_pair(0U, &SystemZ::ADDR32BitRegClass);
 
+    case 'h': // High-part register (an LLVM extension)
+      return std::make_pair(0U, &SystemZ::GRH32BitRegClass);
+
     case 'f': // Floating-point register
       if (VT == MVT::f64)
         return std::make_pair(0U, &SystemZ::FP64BitRegClass);
@@ -733,7 +741,7 @@ static bool canUseSiblingCall(CCState ArgCCInfo,
     if (!VA.isRegLoc())
       return false;
     unsigned Reg = VA.getLocReg();
-    if (Reg == SystemZ::R6L || Reg == SystemZ::R6D)
+    if (Reg == SystemZ::R6H || Reg == SystemZ::R6L || Reg == SystemZ::R6D)
       return false;
   }
   return true;