Complement commit b932f770f70d ("x86_64 frame unwind info"), SVN r46374,
<https://gcc.gnu.org/ml/gcc-patches/2001-10/msg00860.html>, and replace
`-fexceptions -fnon-call-exceptions' with `-fasynchronous-unwind-tables'
in LIB2_DIVMOD_FUNCS compilation flags so as to provide unwind tables
for the affected functions while not pulling the unwinder proper, which
is not required here.
Remove the ARM overrides accordingly, retaining the hook infrastructure
however, and make the ARM test case a generic one.
Beyond saving program space it fixes a RISC-V glibc build error due to
unsatisfied `malloc' and `free' references from the unwinder causing
link errors with `ld.so' where libgcc has been built at -O0.
gcc/
* testsuite/gcc.target/arm/div64-unwinding.c: Rename to...
* testsuite/gcc.dg/div64-unwinding.c: ... this.
libgcc/
* Makefile.in [!LIB2_DIVMOD_EXCEPTION_FLAGS]
(LIB2_DIVMOD_EXCEPTION_FLAGS): Replace `-fexceptions
-fnon-call-exceptions' with `-fasynchronous-unwind-tables'.
* config/arm/t-bpabi (LIB2_DIVMOD_EXCEPTION_FLAGS): Remove
variable.
* config/arm/t-netbsd-eabi (LIB2_DIVMOD_EXCEPTION_FLAGS):
Likewise.
---
Hi,
I realised we still use handwritten ChangeLog entries (I got confused
with now different policies each of the various pieces of the GNU
toolchain has), so here's v2 of the change with a fix for that problem
being the only update.
Also I have since run verification with the `riscv64-linux-gnu' target
and the ilp32d multilib as more representative for the change being made.
No problems were observed, although the now enabled test case scored:
UNSUPPORTED: gcc.dg/div64-unwinding.c
of course with the target failing the `! *-*-linux*' condition.
Given that for the `riscv64-linux-gnu' target and the ilp32d multilib
glibc currently fails to link against libgcc.a built at -O0 I first ran
reference testing with target libraries built at -O2, but comparing that
to change-under-test -O2 results revealed another issue with GCC target
libraries built at -O0 causing link failures across testsuites, namely
libgcov.a referring atomic primitives where libatomic.a has not been
linked in. I haven't figured out yet if the issue is in libgcov, the
testsuite or the specs. Examples of failures:
.../bin/riscv64-linux-gnu-ld:
.../gcc/testsuite/g++/../../lib32/ilp32d/libgcov.a(_gcov_indirect_call_profiler_v4.o):
in function `__gcov_topn_values_profiler_body':
.../libgcc/libgcov-profiler.c:116: undefined reference to `__atomic_fetch_add_8'
.../bin/riscv64-linux-gnu-ld: .../libgcc/libgcov-profiler.c:129: undefined
reference to `__atomic_fetch_add_8'
.../bin/riscv64-linux-gnu-ld: .../libgcc/libgcov-profiler.c:150: undefined
reference to `__atomic_fetch_sub_8'
collect2: error: ld returned 1 exit status
compiler exited with status 1
FAIL: g++.dg/other/pr55650.C -std=gnu++98 (test for excess errors)
There were some odd Fortran failures too, with test cases failing to link,
making the results difficult to interpret. Therefore I decided to arrange
for a special build with first stage GCC built with its target libraries
at -O2, so that first stage glibc builds, and then second stage GCC built
with its target libraries at -O0 and second stage glibc omitted. That
removed the extra Fortran failures regardless of whether this change has
been applied or not, but we may consider looking overall into why a full
`riscv64-linux-gnu' build at -O0 has regressions against -O2 at least in
the ilp32d multilib.
Meanwhile, OK to apply?
Maciej
Changes from v1:
- ChangeLog entries added.
---
gcc/testsuite/gcc.dg/div64-unwinding.c | 25 +++++++++++++++++++++++++
gcc/testsuite/gcc.target/arm/div64-unwinding.c | 25 -------------------------
libgcc/Makefile.in | 2 +-
libgcc/config/arm/t-bpabi | 5 -----
libgcc/config/arm/t-netbsd-eabi | 5 -----
5 files changed, 26 insertions(+), 36 deletions(-)
gcc-libgcc-divmod-asynchronous-unwind-tables.diff
Index: gcc/gcc/testsuite/gcc.dg/div64-unwinding.c
===================================================================
--- /dev/null
+++ gcc/gcc/testsuite/gcc.dg/div64-unwinding.c
@@ -0,0 +1,25 @@
+/* Performing a 64-bit division should not pull in the unwinder. */
+
+/* { dg-do run { target { { ! *-*-linux* } && { ! *-*-uclinux* } } } } */
+/* { dg-skip-if "load causes weak symbol resolution" { vxworks_kernel } } */
+/* { dg-options "-O0" } */
+
+#include <stdlib.h>
+
+long long
+foo (long long c, long long d)
+{
+ return c/d;
+}
+
+long long x = 0;
+long long y = 1;
+
+extern int (*_Unwind_RaiseException) (void *) __attribute__((weak));
+
+int main(void)
+{
+ if (&_Unwind_RaiseException != NULL)
+ abort ();;
+ return foo (x, y);
+}
Index: gcc/gcc/testsuite/gcc.target/arm/div64-unwinding.c
===================================================================
--- gcc.orig/gcc/testsuite/gcc.target/arm/div64-unwinding.c
+++ /dev/null
@@ -1,25 +0,0 @@
-/* Performing a 64-bit division should not pull in the unwinder. */
-
-/* { dg-do run { target { { ! *-*-linux* } && { ! *-*-uclinux* } } } } */
-/* { dg-skip-if "load causes weak symbol resolution" { vxworks_kernel } } */
-/* { dg-options "-O0" } */
-
-#include <stdlib.h>
-
-long long
-foo (long long c, long long d)
-{
- return c/d;
-}
-
-long long x = 0;
-long long y = 1;
-
-extern int (*_Unwind_RaiseException) (void *) __attribute__((weak));
-
-int main(void)
-{
- if (&_Unwind_RaiseException != NULL)
- abort ();;
- return foo (x, y);
-}
Index: gcc/libgcc/Makefile.in
===================================================================
--- gcc.orig/libgcc/Makefile.in
+++ gcc/libgcc/Makefile.in
@@ -533,7 +533,7 @@ endif
ifeq ($(LIB2_DIVMOD_EXCEPTION_FLAGS),)
# Provide default flags for compiling divmod functions, if they haven't been
# set already by a target-specific Makefile fragment.
-LIB2_DIVMOD_EXCEPTION_FLAGS := -fexceptions -fnon-call-exceptions
+LIB2_DIVMOD_EXCEPTION_FLAGS := -fasynchronous-unwind-tables
endif
# Build LIB2_DIVMOD_FUNCS.
Index: gcc/libgcc/config/arm/t-bpabi
===================================================================
--- gcc.orig/libgcc/config/arm/t-bpabi
+++ gcc/libgcc/config/arm/t-bpabi
@@ -13,8 +13,3 @@ LIB2ADDEH = $(srcdir)/config/arm/unwind-
# Add the BPABI names.
SHLIB_MAPFILES += $(srcdir)/config/arm/libgcc-bpabi.ver
-
-# On ARM, specifying -fnon-call-exceptions will needlessly pull in
-# the unwinder in simple programs which use 64-bit division. Omitting
-# the option is safe.
-LIB2_DIVMOD_EXCEPTION_FLAGS := -fexceptions
Index: gcc/libgcc/config/arm/t-netbsd-eabi
===================================================================
--- gcc.orig/libgcc/config/arm/t-netbsd-eabi
+++ gcc/libgcc/config/arm/t-netbsd-eabi
@@ -11,8 +11,3 @@ LIB2ADDEH =
# Add the BPABI names.
SHLIB_MAPFILES += $(srcdir)/config/arm/libgcc-bpabi.ver
-
-# On ARM, specifying -fnon-call-exceptions will needlessly pull in
-# the unwinder in simple programs which use 64-bit division. Omitting
-# the option is safe.
-LIB2_DIVMOD_EXCEPTION_FLAGS := -fexceptions
