Initial implementation of MipsTargetLowering::isLegalAddressingMode.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168230 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index e225b6c..6202ae9 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -3483,6 +3483,26 @@
 }
 
 bool
+MipsTargetLowering::isLegalAddressingMode(const AddrMode &AM, Type *Ty) const {
+  // No global is ever allowed as a base.
+  if (AM.BaseGV)
+    return false;
+
+  switch (AM.Scale) {
+  case 0: // "r+i" or just "i", depending on HasBaseReg.
+    break;
+  case 1:
+    if (!AM.HasBaseReg) // allow "r+i".
+      break;
+    return false; // disallow "r+r" or "r+r+i".
+  default:
+    return false;
+  }
+
+  return true;
+}
+
+bool
 MipsTargetLowering::isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const {
   // The Mips target isn't yet aware of offsets.
   return false;