[Clang] always_inline statement attribute

Motivation:

```
int test(int x, int y) {
    int r = 0;
    [[clang::always_inline]] r += foo(x, y); // force compiler to inline this function here
    return r;
}
```

In 2018, @kuhar proposed "Introduce per-callsite inline intrinsics" in https://reviews.llvm.org/D51200 to solve this motivation case (and many others).

This patch solves this problem with call site attribute. "noinline" statement attribute already landed in D119061. Also, some LLVM Inliner fixes landed so call site attribute is stronger than function attribute.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D120717

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 2636a4d..598fb7f 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -554,6 +554,9 @@ public:
   /// True if the current statement has noinline attribute.
   bool InNoInlineAttributedStmt = false;
 
+  /// True if the current statement has always_inline attribute.
+  bool InAlwaysInlineAttributedStmt = false;
+
   // The CallExpr within the current statement that the musttail attribute
   // applies to.  nullptr if there is no 'musttail' on the current statement.
   const CallExpr *MustTailCall = nullptr;