diff mbox series

[2/3] Fix LIBC_PROG_BINUTILS for -fuse-ld=lld

Message ID 20211026200346.3371750-3-adhemerval.zanella@linaro.org
State Committed
Commit 3d5ecb624638627869e6965410f558b15db6946e
Headers
Series Improve lld support and current status |

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent

Commit Message

Adhemerval Zanella Oct. 26, 2021, 8:03 p.m. UTC 
  GCC does not print the correct linker when -fuse-ld=lld is used with
the -print-prog-name=ld:

  $ gcc -v 2>&1 | tail -n 1
  gcc version 11.2.0 (Ubuntu 11.2.0-7ubuntu2)
  $ gcc
  ld

This is different than for gold:

  $ gcc -fuse-ld=gold -print-prog-name=ld
  ld.gold

Using ld.lld as the static linker name prints the expected result.

This is only required when -fuse-ld=lld is used, if lld is used as
the 'ld' programs (through a symlink) LIBC_PROG_BINUTILS works
as expected.

Checked on x86_64-linux-gnu.
---
 aclocal.m4 | 6 +++++-
 configure  | 6 +++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

Comments

Fangrui Song Oct. 26, 2021, 8:48 p.m. UTC | #1 
On 2021-10-26, Adhemerval Zanella wrote:
>GCC does not print the correct linker when -fuse-ld=lld is used with
>the -print-prog-name=ld:
>
>  $ gcc -v 2>&1 | tail -n 1
>  gcc version 11.2.0 (Ubuntu 11.2.0-7ubuntu2)
>  $ gcc
>  ld
>
>This is different than for gold:
>
>  $ gcc -fuse-ld=gold -print-prog-name=ld
>  ld.gold

I think it may be debatable whether -fuse-ld={bfd,gold,lld} should
affect -print-prog-name=ld output.

   # Should -fuse-ld= do anything with this?
   % aarch64-linux-gnu-gcc -print-prog-name=../bin/ld
   /usr/lib/gcc-cross/aarch64-linux-gnu/10/../../../../aarch64-linux-gnu/bin/../bin/ld

gcc/gcc.c has OPT_fuse_ld_bfd but not OPT_fuse_ld_lld, which may explain
the behavior difference.

Clang does not have the GCC -fuse-ld= --print-prog-name=ld behavior.




>Using ld.lld as the static linker name prints the expected result.
>
>This is only required when -fuse-ld=lld is used, if lld is used as
>the 'ld' programs (through a symlink) LIBC_PROG_BINUTILS works
>as expected.
>
>Checked on x86_64-linux-gnu.
>---
> aclocal.m4 | 6 +++++-
> configure  | 6 +++++-
> 2 files changed, 10 insertions(+), 2 deletions(-)
>
>diff --git a/aclocal.m4 b/aclocal.m4
>index c195c4db56..83da631822 100644
>--- a/aclocal.m4
>+++ b/aclocal.m4
>@@ -114,8 +114,12 @@ if test -n "$path_binutils"; then
>     path_binutils=`(cd $path_binutils; pwd) | sed 's%/*$%/%'`
>     CC="$CC -B$path_binutils"
> fi
>+case "$CC" in
>+    *fuse-ld=lld*) LDNAME=ld.lld;;
>+    *)             LDNAME=ld;;

Perhaps hard code -fuse-ld=bfd and -fuse-ld=gold as well?

I think gcc -print-prog-name=ld.bfd is more robust than
gcc -print-prog-name=ld -fuse-ld=bfd.

>+esac
> AS=`$CC -print-prog-name=as`
>-LD=`$CC -print-prog-name=ld`
>+LD=`$CC -print-prog-name=$LDNAME`
> AR=`$CC -print-prog-name=ar`
> AC_SUBST(AR)
> OBJDUMP=`$CC -print-prog-name=objdump`
>diff --git a/configure b/configure
>index 39d75eb4ed..2a28c58cd6 100755
>--- a/configure
>+++ b/configure
>@@ -4549,8 +4549,12 @@ if test -n "$path_binutils"; then
>     path_binutils=`(cd $path_binutils; pwd) | sed 's%/*$%/%'`
>     CC="$CC -B$path_binutils"
> fi
>+case "$CC" in
>+    *fuse-ld=lld*) LDNAME=ld.lld;;
>+    *)             LDNAME=ld;;
>+esac
> AS=`$CC -print-prog-name=as`
>-LD=`$CC -print-prog-name=ld`
>+LD=`$CC -print-prog-name=$LDNAME`
> AR=`$CC -print-prog-name=ar`
>
> OBJDUMP=`$CC -print-prog-name=objdump`
>-- 
>2.32.0
>
Adhemerval Zanella Oct. 27, 2021, 11:42 a.m. UTC | #2 
On 26/10/2021 17:48, Fangrui Song wrote:
> 
> On 2021-10-26, Adhemerval Zanella wrote:
>> GCC does not print the correct linker when -fuse-ld=lld is used with
>> the -print-prog-name=ld:
>>
>>  $ gcc -v 2>&1 | tail -n 1
>>  gcc version 11.2.0 (Ubuntu 11.2.0-7ubuntu2)
>>  $ gcc
>>  ld
>>
>> This is different than for gold:
>>
>>  $ gcc -fuse-ld=gold -print-prog-name=ld
>>  ld.gold
> 
> I think it may be debatable whether -fuse-ld={bfd,gold,lld} should
> affect -print-prog-name=ld output.
> 
>   # Should -fuse-ld= do anything with this?
>   % aarch64-linux-gnu-gcc -print-prog-name=../bin/ld
>   /usr/lib/gcc-cross/aarch64-linux-gnu/10/../../../../aarch64-linux-gnu/bin/../bin/ld

I think it would make sense, it allows to query the underlying static
linker used by the driver.  What does not make much sense to me is
allow arbitrary paths as input.

>  
> gcc/gcc.c has OPT_fuse_ld_bfd but not OPT_fuse_ld_lld, which may explain
> the behavior difference.

I think this is was oversight from lld gcc support and any case we need
to handle gcc that does not print the correct linker used if we want to
allow a way to set a non-default linker.

> 
> Clang does not have the GCC -fuse-ld= --print-prog-name=ld behavior.
> 
> 
> 
> 

This option is used solely to support --with-binutils.  Maybe we should
just remove it, since it is just simplify the use of a different binutils
and for clang it does not make sense (since it has different the integrated
assembly and different tool names).



>> Using ld.lld as the static linker name prints the expected result.
>>
>> This is only required when -fuse-ld=lld is used, if lld is used as
>> the 'ld' programs (through a symlink) LIBC_PROG_BINUTILS works
>> as expected.
>>
>> Checked on x86_64-linux-gnu.
>> ---
>> aclocal.m4 | 6 +++++-
>> configure  | 6 +++++-
>> 2 files changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/aclocal.m4 b/aclocal.m4
>> index c195c4db56..83da631822 100644
>> --- a/aclocal.m4
>> +++ b/aclocal.m4
>> @@ -114,8 +114,12 @@ if test -n "$path_binutils"; then
>>     path_binutils=`(cd $path_binutils; pwd) | sed 's%/*$%/%'`
>>     CC="$CC -B$path_binutils"
>> fi
>> +case "$CC" in
>> +    *fuse-ld=lld*) LDNAME=ld.lld;;
>> +    *)             LDNAME=ld;;
> 
> Perhaps hard code -fuse-ld=bfd and -fuse-ld=gold as well?
> 
> I think gcc -print-prog-name=ld.bfd is more robust than
> gcc -print-prog-name=ld -fuse-ld=bfd.

It outlines the missing gcc support, since with ld.bfd and ld.gold
does work with gcc.

I will maybe send a patch to remove LIBC_PROG_BINUTILS.

> 
>> +esac
>> AS=`$CC -print-prog-name=as`
>> -LD=`$CC -print-prog-name=ld`
>> +LD=`$CC -print-prog-name=$LDNAME`
>> AR=`$CC -print-prog-name=ar`
>> AC_SUBST(AR)
>> OBJDUMP=`$CC -print-prog-name=objdump`
>> diff --git a/configure b/configure
>> index 39d75eb4ed..2a28c58cd6 100755
>> --- a/configure
>> +++ b/configure
>> @@ -4549,8 +4549,12 @@ if test -n "$path_binutils"; then
>>     path_binutils=`(cd $path_binutils; pwd) | sed 's%/*$%/%'`
>>     CC="$CC -B$path_binutils"
>> fi
>> +case "$CC" in
>> +    *fuse-ld=lld*) LDNAME=ld.lld;;
>> +    *)             LDNAME=ld;;
>> +esac
>> AS=`$CC -print-prog-name=as`
>> -LD=`$CC -print-prog-name=ld`
>> +LD=`$CC -print-prog-name=$LDNAME`
>> AR=`$CC -print-prog-name=ar`
>>
>> OBJDUMP=`$CC -print-prog-name=objdump`
>> -- 
>> 2.32.0
>>
diff mbox series

Patch

diff --git a/aclocal.m4 b/aclocal.m4
index c195c4db56..83da631822 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -114,8 +114,12 @@  if test -n "$path_binutils"; then
     path_binutils=`(cd $path_binutils; pwd) | sed 's%/*$%/%'`
     CC="$CC -B$path_binutils"
 fi
+case "$CC" in
+    *fuse-ld=lld*) LDNAME=ld.lld;;
+    *)             LDNAME=ld;;
+esac
 AS=`$CC -print-prog-name=as`
-LD=`$CC -print-prog-name=ld`
+LD=`$CC -print-prog-name=$LDNAME`
 AR=`$CC -print-prog-name=ar`
 AC_SUBST(AR)
 OBJDUMP=`$CC -print-prog-name=objdump`
diff --git a/configure b/configure
index 39d75eb4ed..2a28c58cd6 100755
--- a/configure
+++ b/configure
@@ -4549,8 +4549,12 @@  if test -n "$path_binutils"; then
     path_binutils=`(cd $path_binutils; pwd) | sed 's%/*$%/%'`
     CC="$CC -B$path_binutils"
 fi
+case "$CC" in
+    *fuse-ld=lld*) LDNAME=ld.lld;;
+    *)             LDNAME=ld;;
+esac
 AS=`$CC -print-prog-name=as`
-LD=`$CC -print-prog-name=ld`
+LD=`$CC -print-prog-name=$LDNAME`
 AR=`$CC -print-prog-name=ar`
 
 OBJDUMP=`$CC -print-prog-name=objdump`