From c7da54edf4c2e3a3eb97eb5fb967143e5071a670 Mon Sep 17 00:00:00 2001
From: Ray Donnelly <mingw.android@gmail.com>
Date: Sat, 12 Apr 2014 13:16:52 +0100
Subject: [PATCH] glibc: Use common arch call to get multilib targets

The previous patch added the function 'CT_DoMultilibTarget()' to
scripts/build/arch/*.sh.

This patch calls the common function to (currently) get just the target
tuple for the current multilib target.

This patch was originally by: Cody P Schafer

Changed by Alexey Neyman: first, try `gcc -print-multiarch`. If it is
supported, use whatever it reports. Otherwise, fall back to our
guesswork. Move "i486" quirk into glibc.sh, as it is specific to glibc
(e.g. uclibc will need i386, which is what GCC reports).

Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>
Signed-off-by: Ray Donnelly <mingw.android@gmail.com>
Signed-off-by: Alexey Neyman <stilor@att.net>
---
 scripts/build/libc/glibc.sh | 19 ++++++++++++++++++-
 scripts/functions           | 19 +++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/scripts/build/libc/glibc.sh b/scripts/build/libc/glibc.sh
index f8c970da..192a0055 100644
--- a/scripts/build/libc/glibc.sh
+++ b/scripts/build/libc/glibc.sh
@@ -137,7 +137,7 @@ do_libc_backend() {
 
         CT_mkdir_pushd "${CT_BUILD_DIR}/build-libc-${libc_mode}${extra_dir//\//_}"
 
-        target=${CT_TARGET}
+        target=$( CT_DoMultilibTarget "${CT_TARGET}" ${extra_flags} )
         case "${target}" in
             # SPARC quirk: glibc 2.23 and newer dropped support for SPARCv8 and
             # earlier (corresponding pthread barrier code is missing). Until this
@@ -147,6 +147,18 @@ do_libc_backend() {
                     target=${target/#sparc-/sparcv9-}
                 fi
                 ;;
+            # x86 quirk: architecture name is i386, but glibc expects i[4567]86 - to
+            # indicate the desired optimization. If it was a multilib variant of x86_64,
+            # then it targets at least NetBurst a.k.a. i786, but we'll follow arch/x86.sh
+            # and set the optimization to i686. Otherwise, replace with the most
+            # conservative choice, i486.
+            i386-*)
+                if [ "${CT_TARGET_ARCH}" = "x86_64" ]; then
+                    target=${target/#i386-/i686-}
+                else
+                    target=${target/#i386-/i486-}
+                fi
+                ;;
         esac
 
         do_libc_backend_once extra_dir="${extra_dir}"               \
@@ -193,6 +205,7 @@ do_libc_backend() {
 #   libc_full           : Build full libc                       : bool      : n
 #   extra_flags         : Extra CFLAGS to use (for multilib)    : string    : (empty)
 #   extra_dir           : Extra subdir for multilib             : string    : (empty)
+#   target              : Build libc using this target (for multilib) : string : ${CT_TARGET}
 do_libc_backend_once() {
     local libc_headers
     local libc_startfiles
@@ -213,6 +226,10 @@ do_libc_backend_once() {
         eval "${arg// /\\ }"
     done
 
+    if [ "${target}" = "" ]; then
+        target="${CT_TARGET}"
+    fi
+
     CT_DoLog EXTRA "Configuring C library"
 
     case "${CT_LIBC}" in
diff --git a/scripts/functions b/scripts/functions
index 70c1ba61..62d264e3 100644
--- a/scripts/functions
+++ b/scripts/functions
@@ -1305,6 +1305,25 @@ CT_DoBuildTargetTuple() {
     CT_ARCH_TARGET_LDFLAGS="${CT_ARCH_TARGET_LDFLAGS} ${CT_ARCH_ENDIAN_LDFLAG}"
 }
 
+# This function determines the target tuple for a given set of compiler
+# flags, using either GCC's multiarch feature (if supported; if not,
+# GCC prints nothing and exits with status 0), falling back to calling
+# the architecture-specific functions.
+CT_DoMultilibTarget() {
+    local target="$1"; shift
+    local -a multi_flags=( "$@" )
+    local gcc_multiarch
+
+    gcc_multiarch=$( "${CT_TARGET}-gcc" -print-multiarch "${multi_flags[@]}" )
+    if [ -n "${gcc_multiarch}" ]; then
+        echo "${gcc_multiarch}"
+        return
+    fi
+
+    # Fall back to arch-specific guesswork
+    CT_DoArchMultilibTarget "${target}" "${multi_flags[@]}"
+}
+
 # This function does pause the build until the user strikes "Return"
 # Usage: CT_DoPause [optional_message]
 CT_DoPause() {