[clang] [CIR] Function calls with aggregate arguments and return values (PR #143377)

[Andy Kaylor via cfe-commits]

================
@@ -312,8 +329,47 @@ RValue CIRGenFunction::emitCall(const CIRGenFunctionInfo &funcInfo,
       assert(!cir::MissingFeatures::opCallBitcastArg());
       cirCallArgs[argNo] = v;
     } else {
-      assert(!cir::MissingFeatures::opCallAggregateArgs());
-      cgm.errorNYI("emitCall: aggregate function call argument");
+      Address src = Address::invalid();
+      if (!arg.isAggregate())
+        cgm.errorNYI(loc, "emitCall: non-aggregate call argument");
+      else
+        src = arg.hasLValue() ? arg.getKnownLValue().getAddress()
+                              : arg.getKnownRValue().getAggregateAddress();
+
+      // Fast-isel and the optimizer generally like scalar values better than
+      // FCAs, so we flatten them if this is safe to do for this argument.
+      auto argRecordTy = cast<cir::RecordType>(argType);
+      auto srcTy = src.getElementType();
+      // FIXME(cir): get proper location for each argument.
+      auto argLoc = loc;
+
+      // If the source type is smaller than the destination type of the
+      // coerce-to logic, copy the source value into a temp alloca the size
+      // of the destination type to allow loading all of it. The bits past
+      // the source value are left undef.
+      // FIXME(cir): add data layout info and compare sizes instead of
+      // matching the types.
+      //
+      // uint64_t SrcSize = CGM.getDataLayout().getTypeAllocSize(SrcTy);
+      // uint64_t DstSize = CGM.getDataLayout().getTypeAllocSize(STy);
+      // if (SrcSize < DstSize) {
+      if (srcTy != argRecordTy)
----------------
andykaylor wrote:

The 'if' needs braces since the 'else' uses them.

https://github.com/llvm/llvm-project/pull/143377