* extend.texi (Extended Asm): Mention that a memory clobber

does not count as a side-effect.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@35110 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8597b35..142e387 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,8 @@
 2000-07-17  Geoffrey Keating  <geoffk@cygnus.com>
 
+       * extend.texi (Extended Asm): Mention that a memory clobber
+       does not count as a side-effect.
+
        * unroll.c (copy_loop_body): Fix one instance of using host
        arithmetic on the target; fixes loop-4 on a 32-bit -> 64-bit
        cross-compile.

diff --git a/gcc/extend.texi b/gcc/extend.texi
index 3b8899b..6eefa62 100644 (file)
--- a/gcc/extend.texi
+++ b/gcc/extend.texi
@@ -2558,7 +2558,10 @@ effect.  But it is valid no matter what the machine.
 If your assembler instruction modifies memory in an unpredictable
 fashion, add @samp{memory} to the list of clobbered registers.  This
 will cause GNU CC to not keep memory values cached in registers across
-the assembler instruction.
+the assembler instruction.  You will also want to add the
+@code{volatile} keyword if the memory affected is not listed in the
+inputs or outputs of the @code{asm}, as the @samp{memory} clobber does
+not count as a side-effect of the @code{asm}.
 
 You can put multiple assembler instructions together in a single
 @code{asm} template, separated either with newlines (written as