-
The function definition may list function notes which are used by
-various passes.
+
+
Function attributes are set to communicate additional information about
+ a function. Function attributes are considered to be part of the function,
+ not of the function type, so functions with different parameter attributes
+ can have the same function type.
+
+
Function attributes are simple keywords that follow the type specified. If
+ multiple attributes are needed, they are space separated. For
+ example:
-define void @f() notes(inline=Always) { ... }
-define void @f() notes(inline=Always,opt-size) { ... }
-define void @f() notes(inline=Never,opt-size) { ... }
-define void @f() notes(opt-size) { ... }
+define void @f() noinline { ... }
+define void @f() alwaysinline { ... }
+define void @f() alwaysinline optsize { ... }
+define void @f() optsize
-- inline=Always
-- This note requests inliner to inline this function irrespective of inlining
-size threshold for this function.
+- alwaysinline
+- This attribute requests inliner to inline this function irrespective of
+inlining size threshold for this function.
-- inline=Never
-- This note requests inliner to never inline this function in any situation.
-This note may not be used together with inline=Always note.
+- noinline
+- This attributes requests inliner to never inline this function in any
+situation. This attribute may not be used together with alwaysinline
+ attribute.
-- opt-size
-- This note suggests optimization passes and code generator passes to make
-choices that help reduce code size.
+- optsize
+- This attribute suggests optimization passes and code generator passes to
+make choices that help reduce code size.
+- noreturn
+- This function attribute indicates that the function never returns. This
+ indicates to LLVM that every call to this function should be treated as if
+ an unreachable instruction immediately followed the call.
+
+- nounwind
+- This function attribute indicates that no exceptions unwind out of the
+ function. Usually this is because the function makes no use of exceptions,
+ but it may also be that the function catches any exceptions thrown when
+ executing it.
+
+- readonly
+- This function attribute indicates that the function has no side-effects
+ except for producing a return value or throwing an exception. The value
+ returned must only depend on the function arguments and/or global variables.
+ It may use values obtained by dereferencing pointers.
+- readnone
+- A readnone function has the same restrictions as a readonly
+ function, but in addition it is not allowed to dereference any pointer arguments
+ or global variables.
-
Any notes that are not documented here are considered invalid notes.