strub: enable conditional support

Targets that don't expose callee stacks to callers, such as nvptx, as
well as -fsplit-stack compilations, violate fundamental assumptions of
the current strub implementation.  This patch enables targets to
disable strub, and disables it when -fsplit-stack is enabled.

When strub support is disabled, the testsuite will now skip strub
tests, and libgcc will not build the strub runtime components.


for  gcc/ChangeLog

	* target.def (have_strub_support_for): New hook.
	* doc/tm.texi.in: Document it.
	* doc/tm.texi: Rebuild.
	* ipa-strub.cc: Include target.h.
	(strub_target_support_p): New.
	(can_strub_p): Call it.  Test for no flag_split_stack.
	(pass_ipa_strub::adjust_at_calls_call): Check for target
	support.
	* config/nvptx/nvptx.cc (TARGET_HAVE_STRUB_SUPPORT_FOR):
	Disable.
	* doc/sourcebuild.texi (strub): Document new effective
	target.

for  gcc/testsuite/ChangeLog

	* c-c++-common/strub-split-stack.c: New.
	* c-c++-common/strub-unsupported.c: New.
	* c-c++-common/strub-unsupported-2.c: New.
	* c-c++-common/strub-unsupported-3.c: New.
	* lib/target-supports.exp (check_effective_target_strub): New.
	* c-c++-common/strub-O0.c: Require effective target strub.
	* c-c++-common/strub-O1.c: Likewise.
	* c-c++-common/strub-O2.c: Likewise.
	* c-c++-common/strub-O2fni.c: Likewise.
	* c-c++-common/strub-O3.c: Likewise.
	* c-c++-common/strub-O3fni.c: Likewise.
	* c-c++-common/strub-Og.c: Likewise.
	* c-c++-common/strub-Os.c: Likewise.
	* c-c++-common/strub-all1.c: Likewise.
	* c-c++-common/strub-all2.c: Likewise.
	* c-c++-common/strub-apply1.c: Likewise.
	* c-c++-common/strub-apply2.c: Likewise.
	* c-c++-common/strub-apply3.c: Likewise.
	* c-c++-common/strub-apply4.c: Likewise.
	* c-c++-common/strub-at-calls1.c: Likewise.
	* c-c++-common/strub-at-calls2.c: Likewise.
	* c-c++-common/strub-defer-O1.c: Likewise.
	* c-c++-common/strub-defer-O2.c: Likewise.
	* c-c++-common/strub-defer-O3.c: Likewise.
	* c-c++-common/strub-defer-Os.c: Likewise.
	* c-c++-common/strub-internal1.c: Likewise.
	* c-c++-common/strub-internal2.c: Likewise.
	* c-c++-common/strub-parms1.c: Likewise.
	* c-c++-common/strub-parms2.c: Likewise.
	* c-c++-common/strub-parms3.c: Likewise.
	* c-c++-common/strub-relaxed1.c: Likewise.
	* c-c++-common/strub-relaxed2.c: Likewise.
	* c-c++-common/strub-short-O0-exc.c: Likewise.
	* c-c++-common/strub-short-O0.c: Likewise.
	* c-c++-common/strub-short-O1.c: Likewise.
	* c-c++-common/strub-short-O2.c: Likewise.
	* c-c++-common/strub-short-O3.c: Likewise.
	* c-c++-common/strub-short-Os.c: Likewise.
	* c-c++-common/strub-strict1.c: Likewise.
	* c-c++-common/strub-strict2.c: Likewise.
	* c-c++-common/strub-tail-O1.c: Likewise.
	* c-c++-common/strub-tail-O2.c: Likewise.
	* c-c++-common/strub-var1.c: Likewise.
	* c-c++-common/torture/strub-callable1.c: Likewise.
	* c-c++-common/torture/strub-callable2.c: Likewise.
	* c-c++-common/torture/strub-const1.c: Likewise.
	* c-c++-common/torture/strub-const2.c: Likewise.
	* c-c++-common/torture/strub-const3.c: Likewise.
	* c-c++-common/torture/strub-const4.c: Likewise.
	* c-c++-common/torture/strub-data1.c: Likewise.
	* c-c++-common/torture/strub-data2.c: Likewise.
	* c-c++-common/torture/strub-data3.c: Likewise.
	* c-c++-common/torture/strub-data4.c: Likewise.
	* c-c++-common/torture/strub-data5.c: Likewise.
	* c-c++-common/torture/strub-indcall1.c: Likewise.
	* c-c++-common/torture/strub-indcall2.c: Likewise.
	* c-c++-common/torture/strub-indcall3.c: Likewise.
	* c-c++-common/torture/strub-inlinable1.c: Likewise.
	* c-c++-common/torture/strub-inlinable2.c: Likewise.
	* c-c++-common/torture/strub-ptrfn1.c: Likewise.
	* c-c++-common/torture/strub-ptrfn2.c: Likewise.
	* c-c++-common/torture/strub-ptrfn3.c: Likewise.
	* c-c++-common/torture/strub-ptrfn4.c: Likewise.
	* c-c++-common/torture/strub-pure1.c: Likewise.
	* c-c++-common/torture/strub-pure2.c: Likewise.
	* c-c++-common/torture/strub-pure3.c: Likewise.
	* c-c++-common/torture/strub-pure4.c: Likewise.
	* c-c++-common/torture/strub-run1.c: Likewise.
	* c-c++-common/torture/strub-run2.c: Likewise.
	* c-c++-common/torture/strub-run3.c: Likewise.
	* c-c++-common/torture/strub-run4.c: Likewise.
	* c-c++-common/torture/strub-run4c.c: Likewise.
	* c-c++-common/torture/strub-run4d.c: Likewise.
	* c-c++-common/torture/strub-run4i.c: Likewise.
	* g++.dg/strub-run1.C: Likewise.
	* g++.dg/torture/strub-init1.C: Likewise.
	* g++.dg/torture/strub-init2.C: Likewise.
	* g++.dg/torture/strub-init3.C: Likewise.
	* gnat.dg/strub_attr.adb: Likewise.
	* gnat.dg/strub_ind.adb: Likewise.
	* gnat.dg/strub_access.adb: Likewise.
	* gnat.dg/strub_access1.adb: Likewise.
	* gnat.dg/strub_disp.adb: Likewise.
	* gnat.dg/strub_disp1.adb: Likewise.
	* gnat.dg/strub_ind1.adb: Likewise.
	* gnat.dg/strub_ind2.adb: Likewise.
	* gnat.dg/strub_intf.adb: Likewise.
	* gnat.dg/strub_intf1.adb: Likewise.
	* gnat.dg/strub_intf2.adb: Likewise.
	* gnat.dg/strub_renm.adb: Likewise.
	* gnat.dg/strub_renm1.adb: Likewise.
	* gnat.dg/strub_renm2.adb: Likewise.
	* gnat.dg/strub_var.adb: Likewise.
	* gnat.dg/strub_var1.adb: Likewise.

for  libgcc/ChangeLog

	* configure.ac: Check for strub support.
	* configure: Rebuilt.
	* Makefile.in: Compile strub.c conditionally.

3 files changed, 40 insertions, 1 deletions

diff --git a/libgcc/Makefile.in b/libgcc/Makefile.in
index d8163c5..3f77283 100644
--- a/libgcc/Makefile.in
+++ b/libgcc/Makefile.in
@@ -434,7 +434,7 @@ LIB2ADD += enable-execute-stack.c
 LIB2ADD += $(srcdir)/hardcfr.c
 
 # Stack scrubbing infrastructure.
-LIB2ADD += $(srcdir)/strub.c
+@HAVE_STRUB_SUPPORT@LIB2ADD += $(srcdir)/strub.c
 
 # While emutls.c has nothing to do with EH, it is in LIB2ADDEH*
 # instead of LIB2ADD because that's the way to be sure on some targets
diff --git a/libgcc/configure b/libgcc/configure
index cf14920..5671589 100755
--- a/libgcc/configure
+++ b/libgcc/configure
@@ -593,6 +593,7 @@ asm_hidden_op
 extra_parts
 cpu_type
 get_gcc_base_ver
+HAVE_STRUB_SUPPORT
 thread_header
 tm_defines
 tm_file
@@ -5702,6 +5703,31 @@ esac
 
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for strub support" >&5
+$as_echo_n "checking for strub support... " >&6; }
+if ${libgcc_cv_strub_support+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void __attribute__ ((__strub__)) fn (void) {}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  libgcc_cv_strub_support=yes
+else
+  libgcc_cv_strub_support=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libgcc_cv_strub_support" >&5
+$as_echo "$libgcc_cv_strub_support" >&6; }
+if test "x$libgcc_cv_strub_support" != xno; then
+  HAVE_STRUB_SUPPORT=
+else
+  HAVE_STRUB_SUPPORT='# '
+fi
+
+
 # Determine what GCC version number to use in filesystem paths.
 
   get_gcc_base_ver="cat"
diff --git a/libgcc/configure.ac b/libgcc/configure.ac
index 2fc9d5d..9c0e415 100644
--- a/libgcc/configure.ac
+++ b/libgcc/configure.ac
@@ -694,6 +694,19 @@ AC_SUBST(tm_defines)
 # Map from thread model to thread header.
 GCC_AC_THREAD_HEADER([$target_thread_file])
 
+AC_CACHE_CHECK([for strub support],
+  [libgcc_cv_strub_support],
+  [AC_COMPILE_IFELSE(
+    [AC_LANG_SOURCE([void __attribute__ ((__strub__)) fn (void) {}])],
+    [libgcc_cv_strub_support=yes],
+    [libgcc_cv_strub_support=no])])
+if test "x$libgcc_cv_strub_support" != xno; then
+  HAVE_STRUB_SUPPORT=
+else
+  HAVE_STRUB_SUPPORT='# '
+fi
+AC_SUBST(HAVE_STRUB_SUPPORT)
+
 # Determine what GCC version number to use in filesystem paths.
 GCC_BASE_VER