[mips][FastISel] Disable code generation for unsupported targets through FastISel.

Summary:
Previously, we would check whether the target is supported or not, only in
fastSelectInstruction(). This means that 64-bit targets could use FastISel too.
We fix this by checking every overridden method of the FastISel class and
by falling back to SelectionDAG if the target isn't supported. This change
should have been committed along with r243638, but somehow I missed it.

Reviewers: dsanders

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D11755

llvm-svn: 243986

llvm/lib/Target/Mips/MipsFastISel.cpp

@@ -267,6 +267,9 @@ unsigned MipsFastISel::emitLogicalOp(unsigned ISDOpc, MVT RetVT,
 }
 
 unsigned MipsFastISel::fastMaterializeAlloca(const AllocaInst *AI) {
+  if (!TargetSupported)
+    return 0;
+
   assert(TLI.getValueType(DL, AI->getType(), true) == MVT::i32 &&
          "Alloca should always return a pointer.");
 
@@ -377,6 +380,9 @@ unsigned MipsFastISel::materializeExternalCallSym(MCSymbol *Sym) {
 // Materialize a constant into a register, and return the register
 // number (or zero if we failed to handle it).
 unsigned MipsFastISel::fastMaterializeConstant(const Constant *C) {
+  if (!TargetSupported)
+    return 0;
+
   EVT CEVT = TLI.getValueType(DL, C->getType(), true);
 
   // Only handle simple types.
@@ -1234,6 +1240,9 @@ bool MipsFastISel::finishCall(CallLoweringInfo &CLI, MVT RetVT,
 }
 
 bool MipsFastISel::fastLowerCall(CallLoweringInfo &CLI) {
+  if (!TargetSupported)
+    return false;
+
   CallingConv::ID CC = CLI.CallConv;
   bool IsTailCall = CLI.IsTailCall;
   bool IsVarArg = CLI.IsVarArg;
@@ -1318,6 +1327,9 @@ bool MipsFastISel::fastLowerCall(CallLoweringInfo &CLI) {
 }
 
 bool MipsFastISel::fastLowerIntrinsicCall(const IntrinsicInst *II) {
+  if (!TargetSupported)
+    return false;
+
   switch (II->getIntrinsicID()) {
   default:
     return false;