[interop][SwiftToCxx] verify that lowered function signature represented all LLVM IR params

Author: hyp

lib/IRGen/GenCall.cpp

@@ -1986,6 +1986,7 @@ SignatureExpansionABIDetails Signature::getUncachedABIDetails(
   SignatureExpansion expansion(IGM, formalType, kind);
   SignatureExpansionABIDetails result;
   expansion.expandFunctionType(&result);
+  result.numParamIRTypesInSignature = expansion.ParamIRTypes.size();
   return result;
 }
 

lib/IRGen/IRABIDetailsProvider.cpp

@@ -188,6 +188,35 @@ class IRABIDetailsProviderImpl {
             result.metadataSourceTypes.push_back(canType);
           });
     }
+    // Verify that the signature param count matches the IR param count.
+    size_t signatureParamCount = 0;
+    result.visitParameterList(
+        [&](const IRABIDetailsProvider::LoweredFunctionSignature::
+                IndirectResultValue &indirectResult) { ++signatureParamCount; },
+        [&](const IRABIDetailsProvider::LoweredFunctionSignature::
+                DirectParameter &param) {
+          param.enumerateRecordMembers([&](clang::CharUnits, clang::CharUnits,
+                                           Type) { ++signatureParamCount; });
+        },
+        [&](const IRABIDetailsProvider::LoweredFunctionSignature::
+                IndirectParameter &param) { ++signatureParamCount; },
+        [&](const IRABIDetailsProvider::LoweredFunctionSignature::
+                GenericRequirementParameter &genericRequirementParam) {
+          ++signatureParamCount;
+        },
+        [&](const IRABIDetailsProvider::LoweredFunctionSignature::
+                MetadataSourceParameter &metadataSrcParam) {
+          ++signatureParamCount;
+        },
+        [&](const IRABIDetailsProvider::LoweredFunctionSignature::
+                ContextParameter &) { ++signatureParamCount; },
+        [&](const IRABIDetailsProvider::LoweredFunctionSignature::
+                ErrorResultValue &) { ++signatureParamCount; });
+    // Return nothing if we were unable to represent the exact signature
+    // parameters.
+    if (signatureParamCount != abiDetails->numParamIRTypesInSignature)
+      return None;
+
     return result;
   }
 

lib/IRGen/Signature.h

@@ -163,6 +163,8 @@ class SignatureExpansionABIDetails {
   bool hasContextParam = false;
   /// True if an error result value indirect parameter is passed to the call.
   bool hasErrorResult = false;
+  /// The number of LLVM IR parameters in the LLVM IR function signature.
+  size_t numParamIRTypesInSignature = 0;
 };
 
 /// A signature represents something which can actually be called.