Re: ppc64le: gcc 12 vs -mabi=ibmlongdouble

[Florian Weimer <fweimer@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 1085 bytes --]

* DJ Delorie via Libc-alpha:

> I've been working on updating glibc for Fedora Rawhide, and have
> stumbled upon this issue (after working around the -Wuse-after-free
> issues with a cflags hack)...  A few of the math tests explicitly add
> -mlong-double-64 but configure adds -mabi=ibmlongdouble
>
> I would guess that we need a "CFLAGS -= -mabi=ibmlongdouble" in all
> the places we add -mlong-double-64 but I don't see an easy way of
> doing that, nor am I sure that's a valid solution.  Alternately, gcc
> could be changed to accept the conflicting flags in a meaningful way,
> if there is one.  Is there an -mabi= that undoes the
> -mabi=ibmlongdouble that we can just add to the -mlong-double-64 flag
> lines?

> cc1: error: '-mabi=ibmlongdouble' requires '-mlong-double-128'

I was able to reproduce with a GCC 12 build configured using
--with-long-double-format=ieee.

I tried the attached patch to remove the unwanted -mabi=ibmlongdouble,
but it does not work: it removes CFLAGS-*.c processing as a side effect.

Any suggestions how we can fix this properly?

Thanks,
Florian

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: 0001-powerpc64le-Filter-out-mabi-longdouble-in-64-bit-dou.patch --]
[-- Type: text/x-patch, Size: 2728 bytes --]

From b865fb6228bea8e956e6413002e7641f10d6e5e6 Mon Sep 17 00:00:00 2001
Message-Id: <b865fb6228bea8e956e6413002e7641f10d6e5e6.1643038207.git.fweimer@redhat.com>
From: Florian Weimer <fweimer@redhat.com>
Date: Mon, 24 Jan 2022 11:19:53 +0100
Subject: [PATCH] powerpc64le: Filter out -mabi=*longdouble in 64-bit double
 tests
To: libc-alpha@sourceware.org

GCC 12 configured with --with-long-double-format=ieee does not
accept -mabi=ibmlongdouble in combination with -mlong-double-64,
but this was how glibc tries to build these tests before this change.

sysdeps/unix/sysv/linux/configure adds -mabi=ibmlongdouble to CFLAGS,
so this variable has to be filtered as well.
---
 sysdeps/powerpc/powerpc64/le/Makefile | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/sysdeps/powerpc/powerpc64/le/Makefile b/sysdeps/powerpc/powerpc64/le/Makefile
index 7c036b45fc..2aaed2b75a 100644
--- a/sysdeps/powerpc/powerpc64/le/Makefile
+++ b/sysdeps/powerpc/powerpc64/le/Makefile
@@ -95,8 +95,12 @@ $(foreach suf,$(all-object-suffixes),\
          $(objpfx)test-narrow-macros-ldbl-64$(suf) \
          $(objpfx)test-nldbl-redirect$(suf) \
          $(objpfx)test-redirection-ldbl-64$(suf) \
-         ): sysdep-CFLAGS := $(filter-out -mabi=ieeelongdouble,$(sysdep-CFLAGS))
-
+         ): CFLAGS := $(filter-out -mabi=%longdouble,$(CFLAGS))
+$(foreach suf,$(all-object-suffixes),\
+         $(objpfx)test-narrow-macros-ldbl-64$(suf) \
+         $(objpfx)test-nldbl-redirect$(suf) \
+         $(objpfx)test-redirection-ldbl-64$(suf) \
+         ): sysdep-CFLAGS := $(filter-out -mabi=%longdouble,$(sysdep-CFLAGS))
 endif
 
 # Newer GCC (>7) doesn't like -mabi=* and -mlong-double-64
@@ -104,14 +108,21 @@ ifeq ($(subdir),misc)
 $(foreach suf,$(all-object-suffixes),\
          $(objpfx)tst-nldbl-warn$(suf) \
          $(objpfx)tst-nldbl-error$(suf) \
-         ): sysdep-CFLAGS := $(filter-out -mabi=ieeelongdouble,$(sysdep-CFLAGS))
+         ): CFLAGS := $(filter-out -mabi=%longdouble,$(CFLAGS))
+$(foreach suf,$(all-object-suffixes),\
+         $(objpfx)tst-nldbl-warn$(suf) \
+         $(objpfx)tst-nldbl-error$(suf) \
+         ): sysdep-CFLAGS := $(filter-out -mabi=%longdouble,$(sysdep-CFLAGS))
 endif
 
 # Newer GCC (>7) doesn't like -mabi=* and -mlong-double-64
 ifeq ($(subdir),argp)
 $(foreach suf,$(all-object-suffixes),\
          $(objpfx)tst-nldbl-argp$(suf) \
-         ): sysdep-CFLAGS := $(filter-out -mabi=ieeelongdouble,$(sysdep-CFLAGS))
+         ): CFLAGS := $(filter-out -mabi=%longdouble,$(CFLAGS))
+$(foreach suf,$(all-object-suffixes),\
+         $(objpfx)tst-nldbl-argp$(suf) \
+         ): sysdep-CFLAGS := $(filter-out -mabi=%longdouble,$(sysdep-CFLAGS))
 endif
 
 
-- 
2.34.1