This patch fixes PR target/79439, which is a recursive call when the 64-bit
code is compiled with -fpic doesn't have the NOP after the call. It is
possible for the function to be overriden at link time. In such a case, the
call should call the module that is overriding the call, rather than itself.
The following patch was tested on a little endian Power8 Linux system (64-bit
only), a big endian Power8 Linux system (both 32-bit and 64-bit), and a big
endian Power7 Linux system (both 32-bit and 64-bit). There were no regressions
in the test suite, and I verified that the new test ran successfully in 64-bit
mode. Can I check this patch into the trunk?
Since the bug was reported against GCC 6, can I apply the patch to GCC 6
assuming the patch applies cleanly and has no regressions after a burn in
period on the GCC 7 trunk?
[gcc]
2017-02-28 Michael Meissner <meiss...@linux.vnet.ibm.com>
PR target/79439
* config/rs6000/predicates.md (current_file_function_operand): Do
not allow self calls to be local if the function is replaceable.
[gcc/testsuite]
2017-02-28 Michael Meissner <meiss...@linux.vnet.ibm.com>
PR target/79439
* gcc.target/powerpc/pr79439.c: New test.
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meiss...@linux.vnet.ibm.com, phone: +1 (978) 899-4797
Index: gcc/config/rs6000/predicates.md
===================================================================
--- gcc/config/rs6000/predicates.md (revision 245787)
+++ gcc/config/rs6000/predicates.md (working copy)
@@ -1110,7 +1110,8 @@ (define_predicate "current_file_function
(and (match_code "symbol_ref")
(match_test "(DEFAULT_ABI != ABI_AIX || SYMBOL_REF_FUNCTION_P (op))
&& (SYMBOL_REF_LOCAL_P (op)
- || op == XEXP (DECL_RTL (current_function_decl), 0))
+ || (op == XEXP (DECL_RTL (current_function_decl), 0)
+ && !decl_replaceable_p (current_function_decl)))
&& !((DEFAULT_ABI == ABI_AIX
|| DEFAULT_ABI == ABI_ELFv2)
&& (SYMBOL_REF_EXTERNAL_P (op)
Index: gcc/testsuite/gcc.target/powerpc/pr79439.c
===================================================================
--- gcc/testsuite/gcc.target/powerpc/pr79439.c (revision 0)
+++ gcc/testsuite/gcc.target/powerpc/pr79439.c (revision 0)
@@ -0,0 +1,26 @@
+/* { dg-do compile { target { powerpc*-*-* && lp64 } } } */
+/* { dg-require-effective-target powerpc_p8vector_ok } */
+/* { dg-options "-O2 -fpic" } */
+
+/* Bug 79439 -- we should not eliminate NOP in 'rec' call because it can be
+ interposed at link time for 64-bit ABIs. We need -fpic to tell the compiler
+ functions may be interposed. */
+
+int f (void);
+
+void
+g (void)
+{
+}
+
+int
+rec (int a)
+{
+ int ret = 0;
+ if (a > 10 && f ())
+ ret += rec (a - 1);
+ g ();
+ return a + ret;
+}
+
+/* { dg-final { scan-assembler-times {\mnop\M} 3 } } */
