Subject: bug#32086: 26.1.50; Floating point exceptions during byte-compilation on alpha-unknown-linux-gnu

From: Paul Eggert <[email-masked]>
Date: Sat, 7 Jul 2018 14:27:39 -0700

Thanks for reporting the bug. Please try the attached patch, which I'd like to 
install into the emacs-26 branch if it fixes your problem.
From 960603eb5677265575b786671719d5746164e18c Mon Sep 17 00:00:00 2001
From: Paul Eggert <[email-masked]>
Date: Sat, 7 Jul 2018 14:24:46 -0700
Subject: [PATCH] Fix floating point exceptions on Alpha (Bug#32086)

* admin/merge-gnulib (GNULIB_MODULES): Add fpieee.
* m4/fpieee.m4: New file, copied from Gnulib.
* m4/gnulib-comp.m4: Regenerate.
---
 admin/merge-gnulib |  2 +-
 lib/gnulib.mk.in   |  2 +-
 m4/fpieee.m4       | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 m4/gnulib-comp.m4  |  3 +++
 4 files changed, 59 insertions(+), 2 deletions(-)
 create mode 100644 m4/fpieee.m4

diff --git a/admin/merge-gnulib b/admin/merge-gnulib
index 42edfbb..b23adc2 100755
--- a/admin/merge-gnulib
+++ b/admin/merge-gnulib
@@ -33,7 +33,7 @@ GNULIB_MODULES=
   d-type diffseq dtoastr dtotimespec dup2
   environ execinfo explicit_bzero faccessat
   fcntl fcntl-h fdatasync fdopendir
-  filemode filevercmp flexmember fstatat fsync
+  filemode filevercmp flexmember fpieee fstatat fsync
   getloadavg getopt-gnu gettime gettimeofday gitlog-to-changelog
   ignore-value intprops largefile lstat
   manywarnings memrchr minmax mkostemp mktime nstrftime
diff --git a/lib/gnulib.mk.in b/lib/gnulib.mk.in
index 71c01e3..e69ae45 100644
--- a/lib/gnulib.mk.in
+++ b/lib/gnulib.mk.in
@@ -21,7 +21,7 @@
 # the same distribution terms as the rest of that program.
 #
 # Generated by gnulib-tool.
-# Reproduce by: gnulib-tool --import --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=close --avoid=dup --avoid=fchdir --avoid=fstat --avoid=malloc-posix --avoid=msvc-inval --avoid=msvc-nothrow --avoid=openat-die --avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select --avoid=setenv --avoid=sigprocmask --avoid=stat --avoid=stdarg --avoid=stdbool --avoid=threadlib --avoid=tzset --avoid=unsetenv --avoid=utime --avoid=utime-h --gnu-make --makefile-name=gnulib.mk.in --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt binary-io byteswap c-ctype c-strcase careadlinkat close-stream count-leading-zeros count-one-bits count-trailing-zeros crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 d-type diffseq dtoastr dtotimespec dup2 environ execinfo explicit_bzero faccessat fcntl fcntl-h fdatasync fdopendir filemode filevercmp flexmember fstatat fsync getloadavg getopt-gnu gettime gettimeofday gitlog-to-changelog ignore-value intprops largefile lstat manywarnings memrchr minmax mkostemp mktime nstrftime pipe2 pselect pthread_sigmask putenv qcopy-acl readlink readlinkat sig2str socklen stat-time std-gnu11 stdalign stddef stdio stpcpy strtoimax symlink sys_stat sys_time tempname time time_r time_rz timegm timer-time timespec-add timespec-sub unlocked-io update-copyright utimens vla warnings
+# Reproduce by: gnulib-tool --import --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --avoid=close --avoid=dup --avoid=fchdir --avoid=fstat --avoid=malloc-posix --avoid=msvc-inval --avoid=msvc-nothrow --avoid=openat-die --avoid=opendir --avoid=raise --avoid=save-cwd --avoid=select --avoid=setenv --avoid=sigprocmask --avoid=stat --avoid=stdarg --avoid=stdbool --avoid=threadlib --avoid=tzset --avoid=unsetenv --avoid=utime --avoid=utime-h --gnu-make --makefile-name=gnulib.mk.in --conditional-dependencies --no-libtool --macro-prefix=gl --no-vc-files alloca-opt binary-io byteswap c-ctype c-strcase careadlinkat close-stream count-leading-zeros count-one-bits count-trailing-zeros crypto/md5 crypto/sha1 crypto/sha256 crypto/sha512 d-type diffseq dtoastr dtotimespec dup2 environ execinfo explicit_bzero faccessat fcntl fcntl-h fdatasync fdopendir filemode filevercmp flexmember fpieee fstatat fsync getloadavg getopt-gnu gettime gettimeofday gitlog-to-changelog ignore-value intprops largefile lstat manywarnings memrchr minmax mkostemp mktime nstrftime pipe2 pselect pthread_sigmask putenv qcopy-acl readlink readlinkat sig2str socklen stat-time std-gnu11 stdalign stddef stdio stpcpy strtoimax symlink sys_stat sys_time tempname time time_r time_rz timegm timer-time timespec-add timespec-sub unlocked-io update-copyright utimens vla warnings

 MOSTLYCLEANFILES += core *.stackdump
diff --git a/m4/fpieee.m4 b/m4/fpieee.m4
new file mode 100644
index 0000000..b58840f
--- /dev/null
+++ b/m4/fpieee.m4
@@ -0,0 +1,54 @@
+# fpieee.m4 serial 2  -*- coding: utf-8 -*-
+dnl Copyright (C) 2007, 2009-2018 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl IEEE 754 standardized three items:
+dnl - The formats of single-float and double-float - nowadays commonly
+dnl   available as 'float' and 'double' in C and C++.
+dnl   No autoconf test needed.
+dnl - The overflow and division by zero behaviour: The result are values
+dnl   '±Inf' and 'NaN', rather than exceptions as it was before.
+dnl   This file provides an autoconf macro for ensuring this behaviour of
+dnl   floating-point operations.
+dnl - A set of conditions (overflow, underflow, inexact, etc.) which can
+dnl   be configured to trigger an exception.
+dnl   This cannot be done in a portable way: it depends on the compiler,
+dnl   libc, kernel, and CPU.  No autoconf macro is provided for this.
+
+dnl Ensure non-trapping behaviour of floating-point overflow and
+dnl floating-point division by zero.
+dnl (For integer overflow, see gcc's -ftrapv option; for integer division by
+dnl zero, see the autoconf macro in intdiv0.m4.)
+
+AC_DEFUN([gl_FP_IEEE],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST])
+  # IEEE behaviour is the default on all CPUs except Alpha and SH
+  # (according to the test results of Bruno Haible's ieeefp/fenv_default.m4
+  # and the GCC 4.1.2 manual).
+  case "$host_cpu" in
+    alpha*)
+      # On Alpha systems, a compiler option provides the behaviour.
+      # See the ieee(3) manual page, also available at
+      # <https://backdrift.org/man/tru64/man3/ieee.3.html>
+      if test -n "$GCC"; then
+        # GCC has the option -mieee.
+        # For full IEEE compliance (rarely needed), use option -mieee-with-inexact.
+        CPPFLAGS="$CPPFLAGS -mieee"
+      else
+        # Compaq (ex-DEC) C has the option -ieee, equivalent to -ieee_with_no_inexact.
+        # For full IEEE compliance (rarely needed), use option -ieee_with_inexact.
+        CPPFLAGS="$CPPFLAGS -ieee"
+      fi
+      ;;
+    sh*)
+      if test -n "$GCC"; then
+        # GCC has the option -mieee.
+        CPPFLAGS="$CPPFLAGS -mieee"
+      fi
+      ;;
+  esac
+])
diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index 167356f..e30ff1f 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -86,6 +86,8 @@ AC_DEFUN
   # Code from module filevercmp:
   # Code from module flexmember:
   # Code from module fpending:
+  # Code from module fpieee:
+  AC_REQUIRE([gl_FP_IEEE])
   # Code from module fstatat:
   # Code from module fsync:
   # Code from module getdtablesize:
@@ -994,6 +996,7 @@ AC_DEFUN
   m4/filemode.m4
   m4/flexmember.m4
   m4/fpending.m4
+  m4/fpieee.m4
   m4/fstatat.m4
   m4/fsync.m4
   m4/getdtablesize.m4
-- 
2.7.4