X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=docs%2FLangRef.rst;h=91f2289d6bf4b50ff5e4f703f175728ffb99a608;hb=7172b38af7ed5d1c1e2c97fadfb0ae0c19aff816;hp=b98332b3f6e23c66ab0d4cacaa29f435ea64713f;hpb=2253a2f52f3c46ae75cd05f5885acb987bd1d6b6;p=oota-llvm.git diff --git a/docs/LangRef.rst b/docs/LangRef.rst index b98332b3f6e..91f2289d6bf 100644 --- a/docs/LangRef.rst +++ b/docs/LangRef.rst @@ -817,17 +817,17 @@ example: This attribute indicates that the inliner should attempt to inline this function into callers whenever possible, ignoring any active inlining size threshold for this caller. -``cold`` - This attribute indicates that this function is rarely called. When - computing edge weights, basic blocks post-dominated by a cold - function call are also considered to be cold; and, thus, given low - weight. ``builtin`` This indicates that the callee function at a call site should be recognized as a built-in function, even though the function's declaration - uses the ``nobuiltin'' attribute. This is only valid at call sites for + uses the ``nobuiltin`` attribute. This is only valid at call sites for direct calls to functions which are declared with the ``nobuiltin`` attribute. +``cold`` + This attribute indicates that this function is rarely called. When + computing edge weights, basic blocks post-dominated by a cold + function call are also considered to be cold; and, thus, given low + weight. ``nonlazybind`` This attribute suppresses lazy symbol binding for the function. This may make calls to the function faster, at the cost of extra program @@ -879,17 +879,21 @@ example: passes make choices that keep the code size of this function low, and otherwise do optimizations specifically to reduce code size. ``readnone`` - This attribute indicates that the function computes its result (or - decides to unwind an exception) based strictly on its arguments, + On a function, this attribute indicates that the function computes its + result (or decides to unwind an exception) based strictly on its arguments, without dereferencing any pointer arguments or otherwise accessing any mutable state (e.g. memory, control registers, etc) visible to caller functions. It does not write through any pointer arguments (including ``byval`` arguments) and never changes any state visible to callers. This means that it cannot unwind exceptions by calling the ``C++`` exception throwing methods. + + On an argument, this attribute indicates that the function does not + dereference that pointer argument, even though it may read or write the + memory that the pointer points to if accessed through other pointers. ``readonly`` - This attribute indicates that the function does not write through - any pointer arguments (including ``byval`` arguments) or otherwise + On a function, this attribute indicates that the function does not write + through any pointer arguments (including ``byval`` arguments) or otherwise modify any state (e.g. memory, control registers, etc) visible to caller functions. It may dereference pointer arguments and read state that may be set in the caller. A readonly function always @@ -897,6 +901,10 @@ example: called with the same set of arguments and global state. It cannot unwind an exception by calling the ``C++`` exception throwing methods. + + On an argument, this attribute indicates that the function does not write + through this pointer argument, even though it may write to the memory that + the pointer points to. ``returns_twice`` This attribute indicates that this function can return twice. The C ``setjmp`` is an example of such a function. The compiler disables