[PATCH 1/3] configure: Allow LD to be LLD 9.0.0 or above and gold

[Fangrui Song <maskray@google.com>]

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On 2020-12-28, H.J. Lu wrote:
>On Mon, Dec 28, 2020 at 11:49 AM Fangrui Song via Libc-alpha
><libc-alpha@sourceware.org> wrote:
>>
>> When using lld as the linker, configure prints a confusing message.
>>
>> *** These critical programs are missing or too old: GNU ld
>>
>> lld>=8 can build glibc with very few patches. lld may be built with a
>> custom version information (e.g. git commit ID), so a version check is not
>> useful at all.
>
>But not all versions of lld can be used to build glibc.  Please find a way
>to check the working lld version.

Replaced this with "configure: Allow LD to be LLD 9.0.0 or above" in https://sourceware.org/git/?p=glibc.git;a=shortlog;h=refs/heads/maskray/lld

8.0.0 needs an additional workaround. Since 9.0.0 is quite common in
distributions, I just set the baseline to 9.0.0 to reduce friction.

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From 49c46455e41f1e0e396b17425eb93c5e0e776e1b Mon Sep 17 00:00:00 2001
From: Fangrui Song <maskray@google.com>
Date: Fri, 13 Mar 2020 13:29:46 -0700
Subject: [PATCH 1/3] configure: Allow LD to be LLD 9.0.0 or above

When using LLD (LLVM linker) as the linker, configure prints a confusing
message.

    *** These critical programs are missing or too old: GNU ld

LLD>=9.0.0 can build glibc with very few patches. (LLD 8.0.0 needs one
workaround for -Wl,-defsym=_begin=0). LLD>=9.0.0 is available on many
distributions, so just set the baseline version to 9.0.0.
---
 configure    | 77 +++++++++++++++++++++++++++++++++++++++++++++++++---
 configure.ac | 20 ++++++++++----
 2 files changed, 88 insertions(+), 9 deletions(-)

diff --git a/configure b/configure
index 6a35553805..f67eb287fc 100755
--- a/configure
+++ b/configure
@@ -4601,9 +4601,10 @@ if test $ac_verc_fail = yes; then
 fi
 
 
-if test -n "`$LD --version | sed -n 's/^GNU \(gold\).*$/\1/p'`"; then
+case $($LD --version) in
+  "GNU gold"*)
   # Accept gold 1.14 or higher
-  for ac_prog in $LD
+    for ac_prog in $LD
 do
   # Extract the first word of "$ac_prog", so it can be a program name with args.
 set dummy $ac_prog; ac_word=$2
@@ -4666,8 +4667,75 @@ if test $ac_verc_fail = yes; then
   LD=: critic_missing="$critic_missing GNU gold"
 fi
 
+    ;;
+  "LLD"*)
+  # Accept LLD 9.0 or higher
+    for ac_prog in $LD
+do
+  # Extract the first word of "$ac_prog", so it can be a program name with args.
+set dummy $ac_prog; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_LD+:} false; then :
+  $as_echo_n "(cached) " >&6
 else
-  for ac_prog in $LD
+  if test -n "$LD"; then
+  ac_cv_prog_LD="$LD" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_prog_LD="$ac_prog"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+LD=$ac_cv_prog_LD
+if test -n "$LD"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $LD" >&5
+$as_echo "$LD" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+  test -n "$LD" && break
+done
+
+if test -z "$LD"; then
+  ac_verc_fail=yes
+else
+  # Found it, now check the version.
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking version of $LD" >&5
+$as_echo_n "checking version of $LD... " >&6; }
+  ac_prog_version=`$LD --version 2>&1 | sed -n 's/^.*LLD.* \([0-9][0-9]*\.[0-9.]*\).*$/\1/p'`
+  case $ac_prog_version in
+    '') ac_prog_version="v. ?.??, bad"; ac_verc_fail=yes;;
+    9.*|[1-9][0-9].*)
+       ac_prog_version="$ac_prog_version, ok"; ac_verc_fail=no;;
+    *) ac_prog_version="$ac_prog_version, bad"; ac_verc_fail=yes;;
+
+  esac
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_prog_version" >&5
+$as_echo "$ac_prog_version" >&6; }
+fi
+if test $ac_verc_fail = yes; then
+  LD=: critic_missing="$critic_missing LLD"
+fi
+
+    ;;
+  *)
+    for ac_prog in $LD
 do
   # Extract the first word of "$ac_prog", so it can be a program name with args.
 set dummy $ac_prog; ac_word=$2
@@ -4730,7 +4798,8 @@ if test $ac_verc_fail = yes; then
   LD=: critic_missing="$critic_missing GNU ld"
 fi
 
-fi
+    ;;
+esac
 
 # These programs are version sensitive.
 
diff --git a/configure.ac b/configure.ac
index 43cfac9d48..59dbf9bda8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -979,18 +979,28 @@ AC_CHECK_PROG_VER(AS, $AS, --version,
 		  [2.1[0-9][0-9]*|2.2[5-9]*|2.[3-9][0-9]*|[3-9].*|[1-9][0-9]*],
 		  AS=: critic_missing="$critic_missing as")
 
-if test -n "`$LD --version | sed -n 's/^GNU \(gold\).*$/\1/p'`"; then
+case $($LD --version) in
+  "GNU gold"*)
   # Accept gold 1.14 or higher
-  AC_CHECK_PROG_VER(LD, $LD, --version,
+    AC_CHECK_PROG_VER(LD, $LD, --version,
 		    [GNU gold.* \([0-9][0-9]*\.[0-9.]*\)],
 		    [1.1[4-9]*|1.[2-9][0-9]*|1.1[0-9][0-9]*|[2-9].*|[1-9][0-9]*],
 		    LD=: critic_missing="$critic_missing GNU gold")
-else
-  AC_CHECK_PROG_VER(LD, $LD, --version,
+    ;;
+  "LLD"*)
+  # Accept LLD 9.0 or higher
+    AC_CHECK_PROG_VER(LD, $LD, --version,
+		    [LLD.* \([0-9][0-9]*\.[0-9.]*\)],
+		    [9.*|[1-9][0-9].*],
+		    LD=: critic_missing="$critic_missing LLD")
+    ;;
+  *)
+    AC_CHECK_PROG_VER(LD, $LD, --version,
 		    [GNU ld.* \([0-9][0-9]*\.[0-9.]*\)],
 		    [2.1[0-9][0-9]*|2.2[5-9]*|2.[3-9][0-9]*|[3-9].*|[1-9][0-9]*],
 		    LD=: critic_missing="$critic_missing GNU ld")
-fi
+    ;;
+esac
 
 # These programs are version sensitive.
 AC_CHECK_TOOL_PREFIX
-- 
2.29.2.729.g45daf8777d-goog