[RS6000] PR96493, powerpc local call linkage failure

[Alan Modra <amodra@gmail.com>]

This corrects current_file_function_operand, an operand predicate used
to determine whether a symbol_ref is safe to use with the local_call
patterns.  Calls between pcrel and non-pcrel code need to go via
linker stubs.  In the case of non-pcrel code to pcrel the stub saves
r2 but there needs to be a nop after the branch for the r2 restore.
So the local_call patterns can't be used there.  For pcrel code to
non-pcrel the local_call patterns could still be used, but I thought
it better to not use them since the call isn't direct.  Code generated
by the corresponding call_nonlocal_aix for pcrel is identical anyway.

Incidentally, without the TREE_CODE () == FUNCTION_DECL test,
gcc.c-torture/compile/pr37433.c and pr37433-1.c ICE.  Also, if you
make the test more strict by disallowing an op without a
SYMBOL_REF_DECL then a bunch of go and split-stack tests fail.  That's
because a prologue call to __morestack can't have a following nop.
(__morestack calls its caller at a fixed offset from the __morestack
call!)

Bootstrapped and regression tested powerpc64le-linux.  OK to apply?

Should I rename current_file_function_operand to something more
meaningful before committing?  direct_local_call_operand perhaps?

gcc/
	PR target/96493
	* config/rs6000/predicates.md (current_file_function_operand): Don't
	accept functions that differ in r2 usage.
gcc/testsuite/
	* gcc.target/powerpc/pr96493.c: New file.

diff --git a/gcc/config/rs6000/predicates.md b/gcc/config/rs6000/predicates.md
index afb7c02f129..2709e46f7e5 100644
--- a/gcc/config/rs6000/predicates.md
+++ b/gcc/config/rs6000/predicates.md
@@ -1051,7 +1051,12 @@
 		    && !((DEFAULT_ABI == ABI_AIX
 			  || DEFAULT_ABI == ABI_ELFv2)
 			 && (SYMBOL_REF_EXTERNAL_P (op)
-			     || SYMBOL_REF_WEAK (op)))")))
+			     || SYMBOL_REF_WEAK (op)))
+		    && !(DEFAULT_ABI == ABI_ELFv2
+			 && SYMBOL_REF_DECL (op) != NULL
+			 && TREE_CODE (SYMBOL_REF_DECL (op)) == FUNCTION_DECL
+			 && (rs6000_fndecl_pcrel_p (SYMBOL_REF_DECL (op))
+			     != rs6000_pcrel_p (cfun)))")))
 
 ;; Return 1 if this operand is a valid input for a move insn.
 (define_predicate "input_operand"
diff --git a/gcc/testsuite/gcc.target/powerpc/pr96493.c b/gcc/testsuite/gcc.target/powerpc/pr96493.c
new file mode 100644
index 00000000000..3ee0fc9fe45
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr96493.c
@@ -0,0 +1,28 @@
+/* { dg-do run } */
+/* { dg-options "-mdejagnu-cpu=powerpc64 -O2" } */
+/* { dg-require-effective-target powerpc_elfv2 } */
+
+/* Test local calls between pcrel and non-pcrel code.
+
+   Despite the cpu=power10 option, the code generated here should just
+   be plain powerpc64, even the necessary linker stubs.  */
+
+int one = 1;
+
+int __attribute__ ((target("cpu=power8"),noclone,noinline))
+p8_func (int x)
+{
+  return x - one;
+}
+
+int __attribute__ ((target("cpu=power10"),noclone,noinline))
+p10_func (int x)
+{
+  return p8_func (x);
+}
+
+int
+main (void)
+{
+  return p10_func (1);
+}

-- 
Alan Modra
Australia Development Lab, IBM