Add check_effective_target_autoincdec.

Add check_effective_target_autoincdec that returns true if a target
runs the auto_inc_dec optimization pass.

    gcc/
	* doc/sourcebuild.texi (autoincdec): Add autoincdec description.

    gcc/testsuite/
	PR middle-end/46932
	* gcc.dg/pr46932.c: Use dg-require-effective-target autoincdec.
	* lib/target-supports.exp: Add check_effective_target_autoincdec.

From-SVN: r251087

gcc/ChangeLog

+2017-08-14  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	PR middle-end/46932
+	* doc/sourcebuild.texi (autoincdec): Add autoincdec description.
+
 2017-08-14  Georg-Johann Lay  <avr@gjlay.de>
 
 	PR target/81754

gcc/doc/sourcebuild.texi

@@ -1846,6 +1846,9 @@ PowerPC target supports executing VSX instructions (ISA 2.06).
 
 @c Please keep this table sorted alphabetically.
 @table @code
+@item autoincdec
+Target supports autoincrement/decrement addressing.
+
 @item avx
 Target supports compiling @code{avx} instructions.
 

gcc/testsuite/ChangeLog

+2017-08-14  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	PR middle-end/46932
+	* gcc.dg/pr46932.c: Use dg-require-effective-target autoincdec.
+	* lib/target-supports.exp: Add check_effective_target_autoincdec.
+
 2017-08-14  Szabolcs Nagy  <szabolcs.nagy@arm.com>
 
 	* gcc.target/aarch64/dbl_mov_immediate_1.c: Add

gcc/testsuite/gcc.dg/pr46932.c

 /* { dg-options "-O2 -fdump-rtl-auto_inc_dec" } */
-
-/* Build on targets which have pre increment.  */
-/* { dg-do compile { target aarch64*-*-* arm*-*-* rs6000-*-* powerpc*-*-* arc*-*-* m32r-*-* tic6x-*-* } } */
+/* { dg-require-effective-target autoincdec } */
 
 /* Check that accesses based on the frame pointer do not
    use auto increment.  */

gcc/testsuite/lib/target-supports.exp

@@ -8482,3 +8482,18 @@ proc check_effective_target_arm_coproc4_ok { } {
     return [check_cached_effective_target arm_coproc4_ok \
 		check_effective_target_arm_coproc4_ok_nocache]
 }
+
+# Return 1 if the target supports the auto_inc_dec optimization pass.
+proc check_effective_target_autoincdec { } {
+    if { ![check_no_compiler_messages auto_incdec assembly { void f () { }
+	 } "-O2 -fdump-rtl-auto_inc_dec" ] } {
+      return 0
+    }
+
+    set dumpfile [glob -nocomplain "auto_incdec[pid].c.\[0-9\]\[0-9\]\[0-9\]r.auto_inc_dec"]
+    if { [file exists $dumpfile ] } {
+	file delete $dumpfile
+	return 1
+    }
+    return 0
+}