host-cpu-c-abi: support for aarch64 ILP32 ABI

[Bruno Haible]

Hi,

Andreas Schwab made me aware of that there is another 32-bit ABI on arm64
CPUs: the so-called "aarch64 ILP32" ABI.

References:
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dai0490a/ar01s01.html
https://wiki.linaro.org/Platform/arm64-ilp32


2017-06-08 Bruno Haible <***@clisp.org>

host-cpu-c-abi: Support for aarch64 ILP32 ABI.
* m4/host-cpu-c-abi.m4 (gl_HOST_CPU_C_ABI): Recognize the aarch64 ILP32
ABI. Set HOST_CPU_C_ABI=arm64-ilp32 and define __arm64_ilp32__ in this
case.

diff --git a/m4/host-cpu-c-abi.m4 b/m4/host-cpu-c-abi.m4
index 1ec2f74..a3a3d43 100644
--- a/m4/host-cpu-c-abi.m4
+++ b/m4/host-cpu-c-abi.m4
@@ -1,4 +1,4 @@
-# host-cpu-c-abi.m4 serial 3
+# host-cpu-c-abi.m4 serial 4
dnl Copyright (C) 2002-2017 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -89,13 +89,21 @@ changequote([,])dnl

arm* | aarch64 )
# Assume arm with EABI.
- # On arm64, the C compiler may be generating 64-bit (= aarch64) code
- # or 32-bit (= arm) code.
+ # On arm64 systems, the C compiler may be generating code in one of
+ # these ABIs:
+ # - aarch64 instruction set, 64-bit pointers, 64-bit 'long': arm64.
+ # - aarch64 instruction set, 32-bit pointers, 32-bit 'long': arm64-ilp32.
+ # - 32-bit instruction set, 32-bit pointers, 32-bit 'long': arm or armhf.
AC_EGREP_CPP([yes],
[#if defined(__aarch64__) || defined(__ARM_64BIT_STATE) || defined(__ARM_PCS_AAPCS64)
yes
#endif],
- [gl_cv_host_cpu_c_abi=arm64],
+ [AC_EGREP_CPP([yes],
+ [#if defined __ILP32__ || defined _ILP32
+ yes
+ #endif],
+ [gl_cv_host_cpu_c_abi=arm64-ilp32],
+ [gl_cv_host_cpu_c_abi=arm64])],
[# Don't distinguish little-endian and big-endian arm, since they
# don't require different machine code for simple operations and
# since the user can distinguish them through the preprocessot
@@ -242,6 +250,9 @@ EOF
#ifndef __armhf__
#undef __armhf__
#endif
+#ifndef __arm64_ilp32__
+#undef __arm64_ilp32__
+#endif
#ifndef __arm64__
#undef __arm64__
#endif