From f40944fcc506601b511018f3208af1c34a6db6e2 Mon Sep 17 00:00:00 2001
From: Edd Barrett <vext01@gmail.com>
Date: Mon, 21 Mar 2022 10:26:12 +0000
Subject: [PATCH] Add the `yk_outline` function attribute.

This annotations does two things:

 - It tells the Yk JIT to outline (not inline) calls to the function,
   when preparing a trace.

 - It adds the `noinline` attribute to the function, thus preventing
   LLVM from re-inlining calls to the function when compiling traces.
---
 clang/include/clang/Basic/Attr.td                         | 7 +++++++
 clang/include/clang/Basic/AttrDocs.td                     | 8 ++++++++
 clang/lib/CodeGen/CodeGenModule.cpp                       | 7 +++++++
 .../Misc/pragma-attribute-supported-attributes-list.test  | 1 +
 4 files changed, 23 insertions(+)

diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 12d09181a2ea87..a9d51d7d59e52c 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -3823,3 +3823,10 @@ def EnforceTCBLeaf : InheritableAttr {
   let Documentation = [EnforceTCBLeafDocs];
   bit InheritEvenIfAlreadyPresent = 1;
 }
+
+def YkOutline : InheritableAttr {
+  let Spellings = [GCC<"yk_outline">, Declspec<"yk_outline">];
+  let Subjects = SubjectList<[Function]>;
+  let Documentation = [YkOutlineDocs];
+  let SimpleHandler = 1;
+}
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index c265a877e3b1ac..ad3846fd2c14b4 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -6045,3 +6045,11 @@ def EnforceTCBLeafDocs : Documentation {
   - ``enforce_tcb_leaf(Name)`` indicates that this function is a part of the TCB named ``Name``
   }];
 }
+
+def YkOutlineDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+  The ``yk_outline`` attribute tells the Yk JIT to outline (not inline) calls
+  to the annotated function.
+  }];
+}
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 49a1396b58e3a2..9347184bc20320 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1868,6 +1868,13 @@ void CodeGenModule::SetLLVMFunctionAttributesForDefinition(const Decl *D,
       B.addAttribute(llvm::Attribute::MinSize);
   }
 
+  if (D->hasAttr<YkOutlineAttr>()) {
+    // Prevent the Yk trace compiler from inlining the call.
+    B.addAttribute("yk_outline");
+    // Prevent LLVM from inlining the call when optimising the trace.
+    B.addAttribute(llvm::Attribute::NoInline);
+  }
+
   F->addAttributes(llvm::AttributeList::FunctionIndex, B);
 
   unsigned alignment = D->getMaxAlignment() / Context.getCharWidth();
diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
index 290306bfb6a239..7a7a4fcb18907d 100644
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -185,4 +185,5 @@
 // CHECK-NEXT: WorkGroupSizeHint (SubjectMatchRule_function)
 // CHECK-NEXT: XRayInstrument (SubjectMatchRule_function, SubjectMatchRule_objc_method)
 // CHECK-NEXT: XRayLogArgs (SubjectMatchRule_function, SubjectMatchRule_objc_method)
+// CHECK-NEXT: YkOutline (SubjectMatchRule_function)
 // CHECK-NEXT: End of supported attributes.