[llvm] [RISCV][GISel] Disable call lowering for integers larger than 2*XLen. (PR #69144)

[Philip Reames via llvm-commits]

================
@@ -153,15 +153,52 @@ struct RISCVCallReturnHandler : public RISCVIncomingValueHandler {
 RISCVCallLowering::RISCVCallLowering(const RISCVTargetLowering &TLI)
     : CallLowering(&TLI) {}
 
+// TODO: Support all argument types.
+static bool isSupportedArgumentType(Type *T, const RISCVSubtarget &Subtarget) {
+  // TODO: Integers larger than 2*XLen are passed indirectly which is not
+  // supported yet.
+  if (T->isIntegerTy())
+    return T->getIntegerBitWidth() <= Subtarget.getXLen() * 2;
+  if (T->isPointerTy())
+    return true;
+  return false;
+}
+
+// TODO: Only integer, pointer and aggregate types are supported now.
+static bool isSupportedReturnType(Type *T, const RISCVSubtarget &Subtarget) {
+  // TODO: Integers larger than 2*XLen are passed indirectly which is not
+  // supported yet.
+  if (T->isIntegerTy())
+    return T->getIntegerBitWidth() <= Subtarget.getXLen() * 2;
+  if (T->isPointerTy())
+    return true;
+
+  if (T->isArrayTy())
+    return isSupportedReturnType(T->getArrayElementType(), Subtarget);
----------------
preames wrote:

I think we're going to need a restriction on array and struct size here as well, but that can be a follow up patch.  

https://github.com/llvm/llvm-project/pull/69144