When compiling MariaDB 10.2 (which uses cfi directives in inline asm,
but gets the conditionals wrong) on Solaris 11.4 with an
x86_64-pc-solaris2.11 gcc using gas, I noticed that this one incorrectly
doesn't use cfi directives although it could/should.
Looking closer, I noticed that the logic in gcc/configure.ac's
gcc_cv_as_cfi_directive test is not only hard to follow due to deeply
nested ifs, but plain wrong in the current case: for 64-bit Solaris/x86,
the .eh_frame section is (and should be) read-only, unlike the 32-bit
case, but is incorrectly rejected.
Unlike what we currently do, configure.ac needs to verify that both the
32 and 64-bit .eh_frame sections are as the toolchain requires them to
be, which is what the current patch does.
Since .eh_frame section test already appeared repeatedly, making the
whole code hard to read due to the redundancy, I've moved it to a shell
function. While gcc/configure.ac itself currently doesn't use those
directly, the generated configure already does, so we should be save
here.
Tested with a standalone script with the necessary boilerplate added on
Solaris 10, 11.3 and 11.4 with /bin/as, bundled gas (2.15, 2.23.1,
2.29), and gas 2.30 on both sparc and x86.
Also bootstrapped without regressions on i386-pc-solaris2.11 and
sparc-sun-solaris2.11 (as/ld, gas/ld, both 32 and 64-bit).
While this only touches Solaris-specific code, it would be nice if one
of the build maintainers could have a look.
Ok for mainline?
Rainer
--
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University
2018-01-30 Rainer Orth <r...@cebitec.uni-bielefeld.de>
* configure.ac (gcc_fn_eh_frame_ro): New function.
(gcc_cv_as_cfi_directive): Check both 32 and 64-bit assembler for
correct .eh_frame permissions.
* configure: Regenerate.
# HG changeset patch
# Parent f67a82dfb4ca8993e0153ceba8d8b064da71ad4d
Fix HAVE_GAS_CFI_DIRECTIVE for x86_64-pc-solaris2.*
diff --git a/gcc/configure.ac b/gcc/configure.ac
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -2754,6 +2754,13 @@ L2:],
[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 () {
+ $gcc_cv_as $1 -o conftest.o conftest.s > /dev/null 2>&1 && \
+ $gcc_cv_objdump -h conftest.o 2>/dev/null | \
+ sed -e '/.eh_frame/!d' -e N | grep READONLY > /dev/null
+}
+
# Check if we have assembler support for unwind directives.
gcc_GAS_CHECK_FEATURE([cfi directives], gcc_cv_as_cfi_directive,
,,
@@ -2769,41 +2776,41 @@ gcc_GAS_CHECK_FEATURE([cfi directives],
# If the linker used on Solaris (like Sun ld) isn't capable of merging
# read-only and read-write sections, we need to make sure that the
# assembler used emits read-write .eh_frame sections.
- if test "x$gcc_cv_ld_ro_rw_mix" != xread-write; then
- if test "x$gcc_cv_objdump" != x; then
- if $gcc_cv_objdump -h conftest.o 2>/dev/null | \
- sed -e /.eh_frame/!d -e N | grep READONLY > /dev/null; then
- gcc_cv_as_cfi_directive=no
- else
- case "$target" in
- i?86-*-solaris2.1[[0-9]]* | x86_64-*-solaris2.1[[0-9]]*)
- # On Solaris/x86, make sure that GCC and assembler agree on using
- # read-only .eh_frame sections for 64-bit.
- if test x$gas = xyes; then
- as_ix86_64_opt="--64"
- else
- as_ix86_64_opt="-xarch=amd64"
- fi
- if $gcc_cv_as $as_ix86_64_opt -o conftest.o conftest.s > /dev/null 2>&1 && \
- $gcc_cv_objdump -h conftest.o 2>/dev/null | \
- sed -e /.eh_frame/!d -e N | \
- grep READONLY > /dev/null; then
- gcc_cv_as_cfi_directive=yes
- else
- gcc_cv_as_cfi_directive=no
- fi
- ;;
- *)
- gcc_cv_as_cfi_directive=yes
- ;;
- esac
- fi
+ if test "x$gcc_cv_ld_ro_rw_mix" = xread-write; then
+ gcc_cv_as_cfi_directive=yes
+ elif test "x$gcc_cv_objdump" = x; then
+ # No objdump, err on the side of caution.
+ gcc_cv_as_cfi_directive=no
+ else
+ if test x$gas = xyes; then
+ as_32_opt="--32"
+ as_64_opt="--64"
else
- # no objdump, err on the side of caution
- gcc_cv_as_cfi_directive=no
+ as_32_opt="-m32"
+ as_64_opt="-m64"
fi
- else
- gcc_cv_as_cfi_directive=yes
+ case "$target" in
+ sparc*-*-solaris2.*)
+ # On Solaris/SPARC, .eh_frame sections should always be read-write.
+ if gcc_fn_eh_frame_ro $as_32_opt \
+ || gcc_fn_eh_frame_ro $as_64_opt; then
+ gcc_cv_as_cfi_directive=no
+ else
+ gcc_cv_as_cfi_directive=yes
+ fi
+ ;;
+ i?86-*-solaris2.* | x86_64-*-solaris2.*)
+ # On Solaris/x86, make sure that GCC and assembler agree on using
+ # read-only .eh_frame sections for 64-bit.
+ if gcc_fn_eh_frame_ro $as_32_opt; then
+ gcc_cv_as_cfi_directive=no
+ elif gcc_fn_eh_frame_ro $as_64_opt; then
+ gcc_cv_as_cfi_directive=yes
+ else
+ gcc_cv_as_cfi_directive=no
+ fi
+ ;;
+ esac
fi
;;
*-*-*)
