From 9b6b7d615543d73381cb1f994825d9bca024c838 Mon Sep 17 00:00:00 2001 From: Sandra Loosemore Date: Thu, 18 Jan 2024 23:19:39 +0000 Subject: [PATCH] Improve documentation of noinline and noipa attributes [PR108470] gcc/ChangeLog PR ipa/108470 * doc/extend.texi (Common Function Attributes): Document that noinline also disables some interprocedural optimizations and improve flow to the part about using inline asm instead to disable calls from being optimized away completely. Remove the sentence that says noipa is mainly for internal compiler testing. --- gcc/doc/extend.texi | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index d879ad544b5..616e26d47dc 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -3666,13 +3666,17 @@ propagation. @cindex @code{noinline} function attribute @item noinline This function attribute prevents a function from being considered for -inlining. +inlining. It also disables some other interprocedural optimizations; it's +preferable to use the more comprehensive @code{noipa} attribute instead +if that is your goal. + @c Don't enumerate the optimizations by name here; we try to be @c future-compatible with this mechanism. -If the function does not have side effects, there are optimizations -other than inlining that cause function calls to be optimized away, -although the function call is live. To keep such calls from being -optimized away, put +Even if a function is declared with the @code{noinline} attribute, +there are optimizations other than inlining that can cause calls to be +optimized away if it does not have side effects, although the function +call is live. To keep such calls from being optimized away, put + @smallexample asm (""); @end smallexample @@ -3691,8 +3695,7 @@ the body. This attribute implies @code{noinline}, @code{noclone} and to a combination of other attributes, because its purpose is to suppress existing and future optimizations employing interprocedural analysis, including those that do not have an attribute suitable for disabling -them individually. This attribute is supported mainly for the purpose -of testing the compiler. +them individually. @cindex @code{nonnull} function attribute @cindex functions with non-null pointer arguments