[aarch64] Distinguish the 'Q' and 'm' inline assembly memory constraints.

Summary:
But still handle them the same way since I don't know how they differ on
this target.

Clang also has code for 'Ump', 'Utf', 'Usa', and 'Ush' but calls
llvm_unreachable() on this code path so they are not converted to a
constraint id at the moment.

No functional change intended.

Reviewers: t.p.northover

Subscribers: aemerson, llvm-commits

Differential Revision: http://reviews.llvm.org/D8177

llvm-svn: 232941

llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp

@@ -212,13 +212,19 @@ static bool isOpcWithIntImmediate(const SDNode *N, unsigned Opc,
 
 bool AArch64DAGToDAGISel::SelectInlineAsmMemoryOperand(
     const SDValue &Op, unsigned ConstraintID, std::vector<SDValue> &OutOps) {
-  assert(ConstraintID == InlineAsm::Constraint_m &&
-         "unexpected asm memory constraint");
-  // Require the address to be in a register.  That is safe for all AArch64
-  // variants and it is hard to do anything much smarter without knowing
-  // how the operand is used.
-  OutOps.push_back(Op);
-  return false;
+  switch(ConstraintID) {
+  default:
+    llvm_unreachable("Unexpected asm memory constraint");
+  case InlineAsm::Constraint_i:
+  case InlineAsm::Constraint_m:
+  case InlineAsm::Constraint_Q:
+    // Require the address to be in a register.  That is safe for all AArch64
+    // variants and it is hard to do anything much smarter without knowing
+    // how the operand is used.
+    OutOps.push_back(Op);
+    return false;
+  }
+  return true;
 }
 
 /// SelectArithImmed - Select an immediate value that can be represented as

llvm/lib/Target/AArch64/AArch64ISelLowering.h

@@ -475,8 +475,12 @@ private:
 
   unsigned getInlineAsmMemConstraint(
       const std::string &ConstraintCode) const override {
-    // FIXME: Map different constraints differently.
-    return InlineAsm::Constraint_m;
+    if (ConstraintCode == "Q")
+      return InlineAsm::Constraint_Q;
+    // FIXME: clang has code for 'Ump', 'Utf', 'Usa', and 'Ush' but these are
+    //        followed by llvm_unreachable so we'll leave them unimplemented in
+    //        the backend for now.
+    return TargetLowering::getInlineAsmMemConstraint(ConstraintCode);
   }
 
   bool isUsedByReturnOnly(SDNode *N, SDValue &Chain) const override;