From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 14 Aug 2009 21:08:36 +0200
Subject: [xen] always inline memcmp
Message-id: 1250276916-30916-3-git-send-email-pbonzini@redhat.com
O-Subject: [RHEL5.5 PATCH 2/2] Always inline memcmp
Bugzilla: 510686
RH-Acked-by: Juan Quintela <quintela@redhat.com>
RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>

Bugzilla: http://bugzilla.redhat.com/show_bug.cgi?id=510686

Brew build: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1929311

Upstream status: see below

GCC assumes the presence of a few string.h functions (memcpy, memset,
memcmp, memmove).  Xen tries to work around this, and force generation
of inline sequences, using this trick:

    #define memcmp __builtin_memcmp

However, this is not the purpose of __builtin_memcmp and there's no
guarantee that it actually expands to string operations unless
the -minline-all-stringops command-line option is given too.  The
attached patch future-proofs the code by passing the flag to GCC.

Upstream instead removed all arch-specific handling of memcmp (revs
16450 and 16454).  The attached patch is preferrable for RHEL since it
won't change at all the generated code.

Test status: used daily for a month.

diff --git a/x86_32.mk b/x86_32.mk
index ce0bb67..dc18d89 100644
--- a/x86_32.mk
+++ b/x86_32.mk
@@ -7,7 +7,7 @@ CONFIG_MIGRATE := y
 CONFIG_XCUTILS := y
 CONFIG_IOEMU := y
 
-CFLAGS += -m32 -march=i686
+CFLAGS += -m32 -march=i686 -minline-all-stringops
 LIBDIR := lib
 
 # Use only if calling $(LD) directly.
diff --git a/x86_64.mk b/x86_64.mk
index 2888786..e43f79f 100644
--- a/x86_64.mk
+++ b/x86_64.mk
@@ -8,7 +8,7 @@ CONFIG_MIGRATE := y
 CONFIG_XCUTILS := y
 CONFIG_IOEMU := y
 
-CFLAGS += -m64
+CFLAGS += -m64 -minline-all-stringops
 LIBDIR = $(LIB64DIR)
 
 # Use only if calling $(LD) directly.