add one addressing mode description hook to rule them all.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35520 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 97c0939..5cd099c 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1940,6 +1940,40 @@
// Loop Strength Reduction hooks
//===----------------------------------------------------------------------===//
+/// isLegalAddressingMode - Return true if the addressing mode represented
+/// by AM is legal for this target, for a load/store of the specified type.
+bool TargetLowering::isLegalAddressingMode(const AddrMode &AM,
+ const Type *Ty) const {
+ // The default implementation of this implements a conservative RISCy, r+r and
+ // r+i addr mode.
+
+ // Allows a sign-extended 16-bit immediate field.
+ if (AM.BaseOffs <= -(1LL << 16) || AM.BaseOffs >= (1LL << 16)-1)
+ return false;
+
+ // No global is ever allowed as a base.
+ if (AM.BaseGV)
+ return false;
+
+ // Only support r+r,
+ switch (AM.Scale) {
+ case 0: // "r+i" or just "i", depending on HasBaseReg.
+ break;
+ case 1:
+ if (AM.HasBaseReg && AM.BaseOffs) // "r+r+i" is not allowed.
+ return false;
+ // Otherwise we have r+r or r+i.
+ break;
+ case 2:
+ if (AM.HasBaseReg || AM.BaseOffs) // 2*r+r or 2*r+i is not allowed.
+ return false;
+ // Allow 2*r as r+r.
+ break;
+ }
+
+ return true;
+}
+
/// isLegalAddressImmediate - Return true if the integer value can be used as
/// the offset of the target addressing mode for load / store of the given
/// type.