[amdgcn] Silence warnings + add gcc_unreachable()

        * config/gcn/gcn.c (gcn_expand_scalar_to_vector_address,
        gcn_md_reorg): Remove unused variables.
        (gcn_emutls_var_init): Add missing (but unreachable) return
        to silence warning.
        (gcn_hsa_declare_function_name): Add gcc_unreachable to ensure
        target != TARGET_GCN3 or TARGET_GCN3 will fail instead of use
        an uninitialized variable.

From-SVN: r278678

gcc/ChangeLog

+2019-11-25  Tobias Burnus  <tobias@codesourcery.com>
+
+	* config/gcn/gcn.c (gcn_expand_scalar_to_vector_address,
+	gcn_md_reorg): Remove unused variables.
+	(gcn_emutls_var_init): Add missing (but unreachable) return
+	to silence warning.
+	(gcn_hsa_declare_function_name): Add gcc_unreachable to ensure
+	target != TARGET_GCN3 or TARGET_GCN3 will fail instead of use
+	an uninitialized variable.
+
 2019-11-25  Martin Jambor  <mjambor@suse.cz>
 
 	PR ipa/92109

gcc/config/gcn/gcn.c

@@ -1783,7 +1783,6 @@ gcn_expand_scalar_to_vector_address (machine_mode mode, rtx exec, rtx mem,
 	  /* tmp[:] += zext (mem_base)  */
 	  if (exec)
 	    {
-	      rtx undef_di = gcn_gen_undef (DImode);
 	      emit_insn (gen_addv64si3_vcc_dup_exec (tmplo, mem_base_lo, tmplo,
 						     vcc, undef_v64si, exec));
 	      emit_insn (gen_addcv64si3_exec (tmphi, tmphi, const0_rtx,
@@ -3213,6 +3212,7 @@ tree
 gcn_emutls_var_init (tree, tree decl, tree)
 {
   sorry_at (DECL_SOURCE_LOCATION (decl), "TLS is not implemented for GCN.");
+  return NULL_TREE;
 }
 
 /* }}}  */
@@ -4340,8 +4340,6 @@ gcn_md_reorg (void)
 {
   basic_block bb;
   rtx exec_reg = gen_rtx_REG (DImode, EXEC_REG);
-  rtx exec_lo_reg = gen_rtx_REG (SImode, EXEC_LO_REG);
-  rtx exec_hi_reg = gen_rtx_REG (SImode, EXEC_HI_REG);
   regset_head live;
 
   INIT_REG_SET (&live);
@@ -4937,6 +4935,8 @@ gcn_hsa_declare_function_name (FILE *file, const char *name, tree)
     granulated_sgprs = (sgpr + extra_regs + 7) / 8 - 1;
   else if (TARGET_GCN5)
     granulated_sgprs = 2 * ((sgpr + extra_regs + 15) / 16 - 1);
+  else
+    gcc_unreachable ();
 
   fputs ("\t.align\t256\n", file);
   fputs ("\t.type\t", file);