[glibc] powerpc64le: workaround ieee long double / _Float128 stdc++ bug

[glibc] powerpc64le: workaround ieee long double / _Float128 stdc++ bug

[Paul E. Murphy]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=8e72163b16bfe874a415a558f78911e5d05c5f22

commit 8e72163b16bfe874a415a558f78911e5d05c5f22
Author: Paul E. Murphy <murphyp@linux.vnet.ibm.com>
Date:   Fri Feb 7 14:08:20 2020 -0600

    powerpc64le: workaround ieee long double / _Float128 stdc++ bug
    
    -mabi=ieeelongdouble triggers the stdc++ libraries _Float128
    support, which then breaks if algorithm is included.  For now,
    explicitly disable _Float128 for such tests.
    
    I have opened up GCC BZ 94080 to track this.
    
    Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>

Diff:
---
 sysdeps/powerpc/powerpc64/le/Makefile | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sysdeps/powerpc/powerpc64/le/Makefile b/sysdeps/powerpc/powerpc64/le/Makefile
index 441a8a14e5..96834d3e2b 100644
--- a/sysdeps/powerpc/powerpc64/le/Makefile
+++ b/sysdeps/powerpc/powerpc64/le/Makefile
@@ -140,3 +140,14 @@ $(foreach suf,$(all-object-suffixes), $(ldbl-ibm128-files)) \
 	  $(foreach r,$(ldbl-128ibm-routines) $(ldbl-tests), \
 		    $(objpfx)$(r)$(suf)): \
   sysdep-CFLAGS := $(filter-out -mabi=ieeelongdouble,$(sysdep-CFLAGS))
+
+# TODO: a bug in stdc++ will fail if -mabi=ieeelongdouble and -mfloat128
+# are both enabled.  The latter is enabled by default in GCC 8+.  This is
+# tracked via GCC BZ 94080.
+ifeq ($(subdir),support)
+CFLAGS-links-dso-program.cc += -mno-float128
+endif
+ifeq ($(subdir),nptl)
+CFLAGS-tst-thread_local1.cc += -mno-float128
+CFLAGS-tst-minstack-throw.cc += -mno-float128
+endif