Remove the unused/undefined `_cmd` parameter in `objc_direct` methods.

When `objc_direct` methods were implemented, the implicit `_cmd` parameter was left as an argument to the method implementation function, but was unset by callers; if the method body referenced the `_cmd` variable, a selector load would be emitted inside the body. However, this leaves an unused argument in the ABI, and is unnecessary.

This change removes the empty/unset argument, and if `_cmd` is referenced inside an `objc_direct` method it will emit local storage for the implicit variable. From the ABI perspective, `objc_direct` methods will have the implicit `self` parameter, immediately followed by whatever explicit arguments are defined on the method, rather than having one unset/undefined register in the middle.

Differential Revision: https://reviews.llvm.org/D131424

1 files changed, 4 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index ff39289..1df9c6b 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -484,9 +484,11 @@ const CGFunctionInfo &
 CodeGenTypes::arrangeObjCMessageSendSignature(const ObjCMethodDecl *MD,
                                               QualType receiverType) {
   SmallVector<CanQualType, 16> argTys;
-  SmallVector<FunctionProtoType::ExtParameterInfo, 4> extParamInfos(2);
+  SmallVector<FunctionProtoType::ExtParameterInfo, 4> extParamInfos(
+      MD->isDirectMethod() ? 1 : 2);
   argTys.push_back(Context.getCanonicalParamType(receiverType));
-  argTys.push_back(Context.getCanonicalParamType(Context.getObjCSelType()));
+  if (!MD->isDirectMethod())
+    argTys.push_back(Context.getCanonicalParamType(Context.getObjCSelType()));
   // FIXME: Kill copy?
   for (const auto *I : MD->parameters()) {
     argTys.push_back(Context.getCanonicalParamType(I->getType()));