i386: Update document for inlining rules

gcc/ChangeLog:

	* doc/extend.texi: Move x86 inlining rule to a new subsubsection
	and add description for inling of function with arch and tune
	attributes.

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index d1b018ee6d6892d8c890c3461e205a043fcf12a9..d701b4d1d412a19a19cbb3621fa6bd8ba186b5e6 100644 (file)
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -7243,11 +7243,6 @@ Prefer 256-bit vector width for instructions.
 Prefer 512-bit vector width for instructions.
 @end table
 
-On the x86, the inliner does not inline a
-function that has different target options than the caller, unless the
-callee has a subset of the target options of the caller.  For example
-a function declared with @code{target("sse3")} can inline a function
-with @code{target("sse2")}, since @code{-msse3} implies @code{-msse2}.
 @end table
 
 @cindex @code{indirect_branch} function attribute, x86
@@ -7361,6 +7356,20 @@ counterpart to option @option{-mno-direct-extern-access}.
 
 @end table
 
+@subsubsection Inlining rules
+On the x86, the inliner does not inline a
+function that has different target options than the caller, unless the
+callee has a subset of the target options of the caller.  For example
+a function declared with @code{target("sse3")} can inline a function
+with @code{target("sse2")}, since @code{-msse3} implies @code{-msse2}.
+
+Besides the basic rule, when a function specifies
+@code{target("arch=@var{ARCH}")} or @code{target("tune=@var{TUNE}")}
+attribute, the inlining rule will be different. It allows inlining of
+a function with default @option{-march=x86-64} and
+@option{-mtune=generic} specified, or a function that has a subset
+of ISA features and marked with always_inline.
+
 @node Xstormy16 Function Attributes
 @subsection Xstormy16 Function Attributes