configury : Fix LEB128 support for non-GNU assemblers.

The current configuration test for LEB128 support in the assembler is
(a) specific to GNU assemblers and (b) only checks that the directives
are accepted, not that they give correct output.

The patch extends the asm test to cover one failure case present in
assemblers based off an older version of GAS (where a 64 bit value with
the MSB set presented to a .uleb128 directive causes a fail).

The test is now generalized such that it does not make use of any
specific test for assembler source/version, but checks that the output
is as expected.  We cater for scanning the object with objdump (either
binutils or LLVM) or Darwin otool.

gcc/ChangeLog:

	* configure.ac (check leb128 support): Check that assemblers both
	accept the LEB128 directives and also give the expected output.
	Add a test for uleb128 with the MSB set for a 64 bit value.
	* configure: Regenerated.

diff --git a/gcc/configure b/gcc/configure
index c0d6dc9..5206f0d 100755 (executable)
--- a/gcc/configure
+++ b/gcc/configure
@@ -23953,6 +23953,8 @@ _ACEOF
 
 
 # Check if we have .[us]leb128, and support symbol arithmetic with it.
+# Older versions of GAS and some non-GNU assemblers, have a bugs handling
+# these directives, even when they appear to accept them.
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking assembler for .sleb128 and .uleb128" >&5
 $as_echo_n "checking assembler for .sleb128 and .uleb128... " >&6; }
 if ${gcc_cv_as_leb128+:} false; then :
@@ -23970,7 +23972,9 @@ fi
 L1:
        .uleb128 1280
        .sleb128 -1010
-L2:' > conftest.s
+L2:
+       .uleb128 0x8000000000000000
+' > conftest.s
     if { ac_try='$gcc_cv_as $gcc_cv_as_flags  -o conftest.o conftest.s >&5'
   { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
   (eval $ac_try) 2>&5
@@ -23978,22 +23982,22 @@ L2:' > conftest.s
   $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
   test $ac_status = 0; }; }
     then
-       # GAS versions before 2.11 do not support uleb128,
-  # despite appearing to.
-  # ??? There exists an elf-specific test that will crash
-  # the assembler.  Perhaps it's better to figure out whether
-  # arbitrary sections are supported and try the test.
-  as_ver=`$gcc_cv_as --version 2>/dev/null | sed 1q`
-  if echo "$as_ver" | grep GNU > /dev/null; then
-    as_vers=`echo $as_ver | sed -n \
-       -e 's,^.*[       ]\([0-9][0-9]*\.[0-9][0-9]*.*\)$,\1,p'`
-    as_major=`expr "$as_vers" : '\([0-9]*\)'`
-    as_minor=`expr "$as_vers" : '[0-9]*\.\([0-9]*\)'`
-    if test $as_major -eq 2 && test $as_minor -lt 11
-    then :
-    else gcc_cv_as_leb128=yes
-    fi
+
+if test "x$gcc_cv_objdump" != x; then
+  if $gcc_cv_objdump -s conftest.o 2>/dev/null \
+     | grep '04800a8e 78808080 80808080 808001' >/dev/null; then
+    gcc_cv_as_leb128=yes
+  fi
+elif test "x$gcc_cv_otool" != x; then
+  if $gcc_cv_otool -d conftest.o 2>/dev/null \
+     | grep '04 80 0a 8e 78 80 80 80 80 80 80 80 80 80 01' >/dev/null; then
+    gcc_cv_as_leb128=yes
   fi
+else
+  # play safe, assume the assembler is broken.
+  :
+fi
+
     else
       echo "configure: failed program was" >&5
       cat conftest.s >&5

diff --git a/gcc/configure.ac b/gcc/configure.ac
index 24679a5..ded124c 100644 (file)
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -3072,34 +3072,38 @@ AC_MSG_RESULT($gcc_cv_ld_ro_rw_mix)
 gcc_AC_INITFINI_ARRAY
 
 # Check if we have .[us]leb128, and support symbol arithmetic with it.
+# Older versions of GAS and some non-GNU assemblers, have a bugs handling
+# these directives, even when they appear to accept them.
 gcc_GAS_CHECK_FEATURE([.sleb128 and .uleb128], gcc_cv_as_leb128,
-  [elf,2,11,0],,
+ [elf,2,11,0],,
 [      .data
        .uleb128 L2 - L1
 L1:
        .uleb128 1280
        .sleb128 -1010
-L2:],
-[[# GAS versions before 2.11 do not support uleb128,
-  # despite appearing to.
-  # ??? There exists an elf-specific test that will crash
-  # the assembler.  Perhaps it's better to figure out whether
-  # arbitrary sections are supported and try the test.
-  as_ver=`$gcc_cv_as --version 2>/dev/null | sed 1q`
-  if echo "$as_ver" | grep GNU > /dev/null; then
-    as_vers=`echo $as_ver | sed -n \
-       -e 's,^.*[       ]\([0-9][0-9]*\.[0-9][0-9]*.*\)$,\1,p'`
-    as_major=`expr "$as_vers" : '\([0-9]*\)'`
-    as_minor=`expr "$as_vers" : '[0-9]*\.\([0-9]*\)'`
-    if test $as_major -eq 2 && test $as_minor -lt 11
-    then :
-    else gcc_cv_as_leb128=yes
-    fi
-  fi]],
-  [AC_DEFINE(HAVE_AS_LEB128, 1,
-    [Define if your assembler supports .sleb128 and .uleb128.])],
-  [AC_DEFINE(HAVE_AS_LEB128, 0,
-    [Define if your assembler supports .sleb128 and .uleb128.])])
+L2:
+       .uleb128 0x8000000000000000
+],
+[[
+if test "x$gcc_cv_objdump" != x; then
+  if $gcc_cv_objdump -s conftest.o 2>/dev/null \
+     | grep '04800a8e 78808080 80808080 808001' >/dev/null; then
+    gcc_cv_as_leb128=yes
+  fi
+elif test "x$gcc_cv_otool" != x; then
+  if $gcc_cv_otool -d conftest.o 2>/dev/null \
+     | grep '04 80 0a 8e 78 80 80 80 80 80 80 80 80 80 01' >/dev/null; then
+    gcc_cv_as_leb128=yes
+  fi
+else
+  # play safe, assume the assembler is broken.
+  :
+fi
+]],
+ [AC_DEFINE(HAVE_AS_LEB128, 1,
+   [Define if your assembler supports .sleb128 and .uleb128.])],
+ [AC_DEFINE(HAVE_AS_LEB128, 0,
+   [Define if your assembler supports .sleb128 and .uleb128.])])
 
 # Determine if an .eh_frame section is read-only.
 gcc_fn_eh_frame_ro () {