[PATCH] D51778: Introduce LLVM_HOT

[Dávid Bolvanský via Phabricator via llvm-commits]

xbolva00 created this revision.
Herald added a subscriber: llvm-commits.

>From GCC docs (I found no docs for this attribute in LLVM docs; but LLVM understands hot/cold attribute too):
"The hot attribute on a function is used to inform the compiler that the function is a hot spot of the compiled program. The function is optimized more aggressively and on many targets it is placed into a special subsection of the text section so all hot functions appear close together, improving locality."

https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes

We can mark Clang/LLVM hotspots with LLVM_HOT as follow-up.


Repository:
  rL LLVM

https://reviews.llvm.org/D51778

Files:
  include/llvm/Support/Compiler.h


Index: include/llvm/Support/Compiler.h
===================================================================
--- include/llvm/Support/Compiler.h
+++ include/llvm/Support/Compiler.h
@@ -217,6 +217,12 @@
 #define LLVM_ATTRIBUTE_RETURNS_NONNULL
 #endif
 
+#if __has_attribute(hot)
+#define LLVM_HOT __attribute__((__hot__))
+#else
+#define LLVM_HOT
+#endif
+
 /// \macro LLVM_ATTRIBUTE_RETURNS_NOALIAS Used to mark a function as returning a
 /// pointer that does not alias any other valid pointer.
 #ifdef __GNUC__


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