[PATCH, i386]: Fix PR81639, ICE in rtl_verify_bb_insns with a naked function

[Uros Bizjak]

Hello!

Naked functions should not sibcall, since in naked functions epilogue
point (placed just above sibcal insn) is unreachable and marked with a
trap insn.

2017-08-01  Uros Bizjak  <ubiz...@gmail.com>

    PR target/81639
    * config/i386/i386.c (ix86_funciton_naked): New prototype.
    (ix86_function_ok_for_sibcall): Return false for naked functions.

testsuite/ChangeLog:

2017-08-01  Uros Bizjak  <ubiz...@gmail.com>

    PR target/81639
    * gcc.target/i386/pr81639.c: New test.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Committed to mainline.

Uros.

Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c  (revision 250758)
+++ config/i386/i386.c  (working copy)
@@ -94,6 +94,7 @@ static rtx legitimize_pe_coff_extern_decl (rtx, bo
 static rtx legitimize_pe_coff_symbol (rtx, bool);
 static void ix86_print_operand_address_as (FILE *, rtx, addr_space_t, bool);
 static bool ix86_save_reg (unsigned int, bool, bool);
+static bool ix86_function_naked (const_tree);
 
 #ifndef CHECK_STACK_LIMIT
 #define CHECK_STACK_LIMIT (-1)
@@ -7929,6 +7930,9 @@ ix86_function_ok_for_sibcall (tree decl, tree exp)
   rtx a, b;
   bool bind_global = decl && !targetm.binds_local_p (decl);
 
+  if (ix86_function_naked (current_function_decl))
+    return false;
+
   /* Sibling call isn't OK if there are no caller-saved registers
      since all registers must be preserved before return.  */
   if (cfun->machine->no_caller_saved_registers)
Index: testsuite/gcc.target/i386/pr81639.c
===================================================================
--- testsuite/gcc.target/i386/pr81639.c (nonexistent)
+++ testsuite/gcc.target/i386/pr81639.c (working copy)
@@ -0,0 +1,12 @@
+/* PR target/81639 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+void b (void);
+
+void
+__attribute__ ((naked))
+a (void)
+{
+  b ();
+}