Reduce the number of arguments in the instruction builder and make some

improvements on instruction selection that account for register and frame
index bases.

Patch contributed by Jeff Cohen. Thanks Jeff!

llvm-svn: 16110

llvm/lib/Target/X86/X86InstrBuilder.h

@@ -28,6 +28,29 @@
 
 namespace llvm {
 
+/// X86AddressMode - This struct holds a generalized full x86 address mode.
+/// The base register can be a frame index, which will eventually be replaced
+/// with BP or SP and Disp being offsetted accordingly.
+/// FIXME: add support for globals as a new base type.
+struct X86AddressMode {
+    enum {
+      UnknownBase,
+      RegBase,
+      FrameIndexBase
+    } BaseType;
+
+    union {
+      unsigned Reg;
+      int FrameIndex;
+    } Base;
+
+    unsigned Scale;
+    unsigned IndexReg;
+    unsigned Disp;
+
+    X86AddressMode() : BaseType(UnknownBase) {}
+};
+
 /// addDirectMem - This function is used to add a direct memory reference to the
 /// current instruction -- that is, a dereference of an address in a register,
 /// with no scale, index or displacement. An example is: DWORD PTR [EAX].
@@ -50,12 +73,16 @@ inline const MachineInstrBuilder &addRegOffset(const MachineInstrBuilder &MIB,
 }
 
 inline const MachineInstrBuilder &addFullAddress(const MachineInstrBuilder &MIB,
-                                                 unsigned BaseReg,
-                                                 unsigned Scale,
-                                                 unsigned IndexReg,
-                                                 unsigned Disp) {
-  assert (Scale == 1 || Scale == 2 || Scale == 4 || Scale == 8);
-  return MIB.addReg(BaseReg).addZImm(Scale).addReg(IndexReg).addSImm(Disp);
+                                                 const X86AddressMode &AM) {
+  assert (AM.Scale == 1 || AM.Scale == 2 || AM.Scale == 4 || AM.Scale == 8);
+
+  if (AM.BaseType == X86AddressMode::RegBase)
+    MIB.addReg(AM.Base.Reg);
+  else if (AM.BaseType == X86AddressMode::FrameIndexBase)
+    MIB.addFrameIndex(AM.Base.FrameIndex);
+  else
+    assert (0);
+  return MIB.addZImm(AM.Scale).addReg(AM.IndexReg).addSImm(AM.Disp);
 }
 
 /// addFrameReference - This function is used to add a reference to the base of