diff mbox series

Check for working assembler --gdwarf-[45] options

Message ID 20201016175834.2289120-1-hjl.tools@gmail.com
State New
Headers show
Series Check for working assembler --gdwarf-[45] options | expand

Commit Message

H.J. Lu Oct. 16, 2020, 5:58 p.m. UTC 
Don't set HAVE_AS_GDWARF_5_DEBUG_FLAG nor HAVE_AS_WORKING_DWARF_4_FLAG
if there is an extra assembly input file in debug info generated by
--gdwarf-5/--gdwarf-4:

https://sourceware.org/bugzilla/show_bug.cgi?id=25878
https://sourceware.org/bugzilla/show_bug.cgi?id=26740

Also replace success with dwarf4_success in the 32-bit --gdwarf-4 check.

OK for master?

	PR bootstrap/97451
	* configure.ac (HAVE_AS_GDWARF_5_DEBUG_FLAG): Don't define if
	there is an extra assembly input file in debug info.
	(HAVE_AS_WORKING_DWARF_4_FLAG): Likewise.  Replace success with
	dwarf4_success in the 32-bit --gdwarf-4 check.
	* configure: Regenerated.
---
 gcc/configure    | 114 ++++++++++++++++++++++++++++++++++++++++++++---
 gcc/configure.ac |  70 ++++++++++++++++++++++++++---
 2 files changed, 172 insertions(+), 12 deletions(-)

Comments

Jakub Jelinek Oct. 16, 2020, 6:17 p.m. UTC | #1 
On Fri, Oct 16, 2020 at 10:58:34AM -0700, H.J. Lu wrote:
> Don't set HAVE_AS_GDWARF_5_DEBUG_FLAG nor HAVE_AS_WORKING_DWARF_4_FLAG
> if there is an extra assembly input file in debug info generated by
> --gdwarf-5/--gdwarf-4:
> 
> https://sourceware.org/bugzilla/show_bug.cgi?id=25878
> https://sourceware.org/bugzilla/show_bug.cgi?id=26740
> 
> Also replace success with dwarf4_success in the 32-bit --gdwarf-4 check.
> 
> OK for master?
> 
> 	PR bootstrap/97451
> 	* configure.ac (HAVE_AS_GDWARF_5_DEBUG_FLAG): Don't define if
> 	there is an extra assembly input file in debug info.
> 	(HAVE_AS_WORKING_DWARF_4_FLAG): Likewise.  Replace success with
> 	dwarf4_success in the 32-bit --gdwarf-4 check.
> 	* configure: Regenerated.

The HAVE_AS_GDWARF_5_DEBUG_FLAG macro should be solely about whether
-gdwarf-5 can be passed to as, nothing else.  That is because it is not only
used to decide if we can pass -gdwarf-5 to as for assembly of e.g. *.c
compilation, but also if we can pass it to as when gcc driver is invoked on
*.s and *.S.  And in that case the problems with -gdwarf-N having unwanted
effects on assembly with compiler generated .debug_info etc. sections.
don't really matter.

The HAVE_AS_WORKING_DWARF_4_FLAG perhaps could be renamed to
...DWARF_N_FLAG, it is meant to check for whether we can safely pass the
option also for *.c etc. compilation when we emit debug info sections by the
compiler.

For that, the question is, are all the issues already fixed on the binutils
trunk?  As in, do I get identical object files e.g. for -gdwarf-2
compilation no matter whether the compiler passes -gdwarf-2 to gas or not
(assuming dwarf 2 is the default in gas) when compiling various *.c/*.C
files?  Ditto for modified gas that would default to other .debug_line
versions and corresponding gcc -gdwarf-N flag and passing vs. not passing
that -gdwarf-N to gas?

The hope is that -gdwarf-N to gas would have two functions:
1) if the assembly doesn't contain .debug* sections/.file/.loc directives,
   emit debug info (mainly .debug_line) for the assembler file in order to
   be able to debug those
2) if the assembly does contain .debug* sections/.file/.loc directives,
   only change the version of the .debug_line generated for the .file/.loc
   directives, but nothing else; keep all .debug* sections but .debug_line
   as is

	Jakub
H.J. Lu Oct. 16, 2020, 6:29 p.m. UTC | #2 
On Fri, Oct 16, 2020 at 11:17 AM Jakub Jelinek <jakub@redhat.com> wrote:
>
> On Fri, Oct 16, 2020 at 10:58:34AM -0700, H.J. Lu wrote:
> > Don't set HAVE_AS_GDWARF_5_DEBUG_FLAG nor HAVE_AS_WORKING_DWARF_4_FLAG
> > if there is an extra assembly input file in debug info generated by
> > --gdwarf-5/--gdwarf-4:
> >
> > https://sourceware.org/bugzilla/show_bug.cgi?id=25878
> > https://sourceware.org/bugzilla/show_bug.cgi?id=26740
> >
> > Also replace success with dwarf4_success in the 32-bit --gdwarf-4 check.
> >
> > OK for master?
> >
> >       PR bootstrap/97451
> >       * configure.ac (HAVE_AS_GDWARF_5_DEBUG_FLAG): Don't define if
> >       there is an extra assembly input file in debug info.
> >       (HAVE_AS_WORKING_DWARF_4_FLAG): Likewise.  Replace success with
> >       dwarf4_success in the 32-bit --gdwarf-4 check.
> >       * configure: Regenerated.
>
> The HAVE_AS_GDWARF_5_DEBUG_FLAG macro should be solely about whether
> -gdwarf-5 can be passed to as, nothing else.  That is because it is not only
> used to decide if we can pass -gdwarf-5 to as for assembly of e.g. *.c
> compilation, but also if we can pass it to as when gcc driver is invoked on
> *.s and *.S.  And in that case the problems with -gdwarf-N having unwanted
> effects on assembly with compiler generated .debug_info etc. sections.
> don't really matter.
>
> The HAVE_AS_WORKING_DWARF_4_FLAG perhaps could be renamed to
> ...DWARF_N_FLAG, it is meant to check for whether we can safely pass the
> option also for *.c etc. compilation when we emit debug info sections by the
> compiler.
>
> For that, the question is, are all the issues already fixed on the binutils
> trunk?  As in, do I get identical object files e.g. for -gdwarf-2

Not yet.  This patch:

https://sourceware.org/pipermail/binutils/2020-October/113744.html

is needed for binutils master branch.  BTW, binutils 2.35 and 2.35.1 are
broken.

> compilation no matter whether the compiler passes -gdwarf-2 to gas or not
> (assuming dwarf 2 is the default in gas) when compiling various *.c/*.C
> files?  Ditto for modified gas that would default to other .debug_line
> versions and corresponding gcc -gdwarf-N flag and passing vs. not passing
> that -gdwarf-N to gas?
>
> The hope is that -gdwarf-N to gas would have two functions:
> 1) if the assembly doesn't contain .debug* sections/.file/.loc directives,
>    emit debug info (mainly .debug_line) for the assembler file in order to
>    be able to debug those
> 2) if the assembly does contain .debug* sections/.file/.loc directives,
>    only change the version of the .debug_line generated for the .file/.loc
>    directives, but nothing else; keep all .debug* sections but .debug_line
>    as is
diff mbox series

Patch

diff --git a/gcc/configure b/gcc/configure
index abff47d30eb..d63c2331157 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -28475,6 +28475,7 @@  $as_echo "#define HAVE_AS_GDWARF2_DEBUG_FLAG 1" >>confdefs.h
 fi
 
 
+ dwarf5_success=no
  { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for --gdwarf-5 option" >&5
 $as_echo_n "checking assembler for --gdwarf-5 option... " >&6; }
 if ${gcc_cv_as_gdwarf_5_flag+:} false; then :
@@ -28506,9 +28507,7 @@  fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_gdwarf_5_flag" >&5
 $as_echo "$gcc_cv_as_gdwarf_5_flag" >&6; }
 if test $gcc_cv_as_gdwarf_5_flag = yes; then
-
-$as_echo "#define HAVE_AS_GDWARF_5_DEBUG_FLAG 1" >>confdefs.h
-
+  dwarf5_success=yes
 fi
 
 
@@ -28701,7 +28700,7 @@  fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_debug_line_32_flag" >&5
 $as_echo "$gcc_cv_as_debug_line_32_flag" >&6; }
 if test $gcc_cv_as_debug_line_32_flag = yes; then
-  success=yes
+  dwarf4_success=yes
 fi
 
    else
@@ -28741,6 +28740,7 @@  fi
 
    fi
    if test $dwarf4_success = yes; then
+     dwarf4_success=no
      { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for --gdwarf-4 not refusing compiler generated .debug_line" >&5
 $as_echo_n "checking assembler for --gdwarf-4 not refusing compiler generated .debug_line... " >&6; }
 if ${gcc_cv_as_dwarf_4_debug_line_flag+:} false; then :
@@ -28772,9 +28772,7 @@  fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_dwarf_4_debug_line_flag" >&5
 $as_echo "$gcc_cv_as_dwarf_4_debug_line_flag" >&6; }
 if test $gcc_cv_as_dwarf_4_debug_line_flag = yes; then
-
-$as_echo "#define HAVE_AS_WORKING_DWARF_4_FLAG 1" >>confdefs.h
-
+  dwarf4_success=yes
 fi
 
      break
@@ -28785,6 +28783,108 @@  fi
    dwarf4_line_sz=5
  done
 
+ conftest_s="\
+	.text
+	.globl	foo
+	.type	foo, %function
+foo:
+	$insn
+	.size	foo, .-foo
+	.file	0 \"foo.c\"
+"
+ if test $dwarf5_success = yes; then
+   dwarf5_success=no
+   { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for working --gdwarf-5 option" >&5
+$as_echo_n "checking assembler for working --gdwarf-5 option... " >&6; }
+if ${gcc_cv_as_working_gdwarf_5_flag+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  gcc_cv_as_working_gdwarf_5_flag=no
+  if test x$gcc_cv_as != x; then
+    $as_echo "$conftest_s" > conftest.s
+    if { ac_try='$gcc_cv_as $gcc_cv_as_flags --gdwarf-5 -o conftest.o conftest.s >&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+    then
+	      if test x$gcc_cv_readelf != x \
+	 && $gcc_cv_readelf -w conftest.o 2>&1 \
+		| grep conftest.s > /dev/null 2>&1; then
+	dwarf5_success=no
+      else
+	dwarf5_success=yes
+      fi
+          else
+      echo "configure: failed program was" >&5
+      cat conftest.s >&5
+    fi
+    rm -f conftest.o conftest.s
+  fi
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_working_gdwarf_5_flag" >&5
+$as_echo "$gcc_cv_as_working_gdwarf_5_flag" >&6; }
+
+
+   if test $dwarf5_success = yes; then
+
+$as_echo "#define HAVE_AS_GDWARF_5_DEBUG_FLAG 1" >>confdefs.h
+
+   fi
+ fi
+
+ conftest_s="\
+	.text
+	.globl	foo
+	.type	foo, %function
+foo:
+	$insn
+	.size	foo, .-foo
+	.file	1 \"foo.c\"
+"
+ if test $dwarf4_success = yes; then
+   dwarf4_success=no
+   { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for working --gdwarf-4 option" >&5
+$as_echo_n "checking assembler for working --gdwarf-4 option... " >&6; }
+if ${gcc_cv_as_working_gdwarf_4_flag+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  gcc_cv_as_working_gdwarf_4_flag=no
+  if test x$gcc_cv_as != x; then
+    $as_echo "$conftest_s" > conftest.s
+    if { ac_try='$gcc_cv_as $gcc_cv_as_flags --gdwarf-4 -o conftest.o conftest.s >&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+    then
+	      if test x$gcc_cv_readelf != x \
+	 && $gcc_cv_readelf -w conftest.o 2>&1 \
+		| grep conftest.s > /dev/null 2>&1; then
+	dwarf4_success=no
+      else
+	dwarf4_success=yes
+      fi
+          else
+      echo "configure: failed program was" >&5
+      cat conftest.s >&5
+    fi
+    rm -f conftest.o conftest.s
+  fi
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_as_working_gdwarf_4_flag" >&5
+$as_echo "$gcc_cv_as_working_gdwarf_4_flag" >&6; }
+
+
+   if test $dwarf4_success = yes; then
+
+$as_echo "#define HAVE_AS_WORKING_DWARF_4_FLAG 1" >>confdefs.h
+
+   fi
+ fi
+
  { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for --gstabs option" >&5
 $as_echo_n "checking assembler for --gstabs option... " >&6; }
 if ${gcc_cv_as_gstabs_flag+:} false; then :
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 26a5d8e3619..0da3009fa5d 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -5197,11 +5197,11 @@  if test x"$insn" != x; then
   [AC_DEFINE(HAVE_AS_GDWARF2_DEBUG_FLAG, 1,
 [Define if your assembler supports the --gdwarf2 option.])])
 
+ dwarf5_success=no
  gcc_GAS_CHECK_FEATURE([--gdwarf-5 option],
   gcc_cv_as_gdwarf_5_flag,
   [elf,2,36,0], [--gdwarf-5], [$insn],,
-  [AC_DEFINE(HAVE_AS_GDWARF_5_DEBUG_FLAG, 1,
-[Define if your assembler supports the --gdwarf-5 option.])])
+  [dwarf5_success=yes])
 
  dwarf4_debug_info_size=0x46
  dwarf4_high_pc_form=7
@@ -5364,7 +5364,7 @@  foo:
      gcc_GAS_CHECK_FEATURE([assembly of compiler generated 32-bit .debug_line],
       gcc_cv_as_debug_line_32_flag,
       [elf,2,36,0], [], [$conftest_s],,
-      [success=yes])
+      [dwarf4_success=yes])
    else
      gcc_GAS_CHECK_FEATURE([assembly of compiler generated 64-bit .debug_line],
       gcc_cv_as_debug_line_64_flag,
@@ -5372,11 +5372,11 @@  foo:
       [dwarf4_success=yes])
    fi
    if test $dwarf4_success = yes; then
+     dwarf4_success=no
      gcc_GAS_CHECK_FEATURE([--gdwarf-4 not refusing compiler generated .debug_line],
       gcc_cv_as_dwarf_4_debug_line_flag,
       [elf,2,36,0], [--gdwarf-4], [$conftest_s],,
-      [AC_DEFINE(HAVE_AS_WORKING_DWARF_4_FLAG, 1,
-[Define if your assembler supports --gdwarf-4 even with compiler generated .debug_line])])
+      [dwarf4_success=yes])
      break
    fi
    dwarf4_debug_info_size=0x36
@@ -5385,6 +5385,66 @@  foo:
    dwarf4_line_sz=5
  done
 
+ conftest_s="\
+	.text
+	.globl	foo
+	.type	foo, %function
+foo:
+	$insn
+	.size	foo, .-foo
+	.file	0 \"foo.c\"
+"
+ if test $dwarf5_success = yes; then
+   dwarf5_success=no
+   gcc_GAS_CHECK_FEATURE([working --gdwarf-5 option],
+     gcc_cv_as_working_gdwarf_5_flag,,
+     [--gdwarf-5],
+     [$conftest_s],
+     [changequote(,)dnl
+      if test x$gcc_cv_readelf != x \
+	 && $gcc_cv_readelf -w conftest.o 2>&1 \
+		| grep conftest.s > /dev/null 2>&1; then
+	dwarf5_success=no
+      else
+	dwarf5_success=yes
+      fi
+      changequote([,])dnl])
+   if test $dwarf5_success = yes; then
+     AC_DEFINE(HAVE_AS_GDWARF_5_DEBUG_FLAG, 1,
+[Define if your assembler supports the --gdwarf-5 option.])
+   fi
+ fi
+
+ conftest_s="\
+	.text
+	.globl	foo
+	.type	foo, %function
+foo:
+	$insn
+	.size	foo, .-foo
+	.file	1 \"foo.c\"
+"
+ if test $dwarf4_success = yes; then
+   dwarf4_success=no
+   gcc_GAS_CHECK_FEATURE([working --gdwarf-4 option],
+     gcc_cv_as_working_gdwarf_4_flag,,
+     [--gdwarf-4],
+     [$conftest_s],
+     [changequote(,)dnl
+      if test x$gcc_cv_readelf != x \
+	 && $gcc_cv_readelf -w conftest.o 2>&1 \
+		| grep conftest.s > /dev/null 2>&1; then
+	dwarf4_success=no
+      else
+	dwarf4_success=yes
+      fi
+      changequote([,])dnl])
+   if test $dwarf4_success = yes; then
+     AC_DEFINE(HAVE_AS_WORKING_DWARF_4_FLAG, 1,
+[Define if your assembler supports --gdwarf-4 even with compiler generated .debug_line])
+   fi
+ fi
+
  gcc_GAS_CHECK_FEATURE([--gstabs option],
   gcc_cv_as_gstabs_flag,
   [elf,2,11,0], [--gstabs], [$insn],,