[mid-end][__RTL] Clean state despite unspecified __RTL startwith passes

Hi there,

When compiling an __RTL function that has an unspecified "startwith"
pass we currently don't run the cleanup pass, this means that we ICE on
the next function (if it's a basic function).

This change ensures that the clean_state pass is run even if the
startwith pass is unspecified.

We also ensure the name of the startwith pass is always freed correctly.

As an example, before this change the following code would ICE when compiling
the function `foo_a`.

When compiled with
./aarch64-none-linux-gnu-gcc -O0 -S unspecified-pass-error.c -o test.s

```
int __RTL () badfoo ()
{
(function "badfoo"
  (insn-chain
    (block 2
      (edge-from entry (flags "FALLTHRU"))
      (cnote 3 [bb 2] NOTE_INSN_BASIC_BLOCK)
      (cinsn 101 (set (reg:DI x19) (reg:DI x0)))
      (cinsn 10 (use (reg/i:SI x19)))
      (edge-to exit (flags "FALLTHRU"))
    ) ;; block 2
  ) ;; insn-chain
) ;; function "foo2"
}

int
foo_a ()
{
  return 200;
}
```

Now it silently ignores the __RTL function and successfully compiles foo_a.

regtest done on aarch64
regtest done on x86_64

OK for trunk?

gcc/ChangeLog:

2019-11-18  Matthew Malcomson  <matthew.malcomson@arm.com>

	* run-rtl-passes.c (run_rtl_passes): Accept and handle empty
	"initial_pass_name" argument -- by running "*clean_state" pass.
	Also free the "initial_pass_name" when done.

gcc/c/ChangeLog:

2019-11-18  Matthew Malcomson  <matthew.malcomson@arm.com>

	* c-parser.c (c_parser_parse_rtl_body): Always call
	run_rtl_passes, even if startwith pass is not provided.

gcc/testsuite/ChangeLog:

2019-11-18  Matthew Malcomson  <matthew.malcomson@arm.com>

	* gcc.dg/rtl/aarch64/unspecified-pass-error.c: New test.

From-SVN: r278393

6 files changed, 70 insertions, 20 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f5d4d77..78a9182 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2019-11-18  Matthew Malcomson  <matthew.malcomson@arm.com>
+
+	* run-rtl-passes.c (run_rtl_passes): Accept and handle empty
+	"initial_pass_name" argument -- by running "*clean_state" pass.
+	Also free the "initial_pass_name" when done.
+
 2019-11-18  Richard Biener  <rguenther@suse.de>
 
 	PR rtl-optimization/92462
diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index 0076e83..0658ea0d 100644
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -1,3 +1,8 @@
+2019-11-18  Matthew Malcomson  <matthew.malcomson@arm.com>
+
+	* c-parser.c (c_parser_parse_rtl_body): Always call
+	run_rtl_passes, even if startwith pass is not provided.
+
 2019-11-15  Joseph Myers  <joseph@codesourcery.com>
 
 	* c-parser.c (c_parser_std_attribute_specifier): Diagnose
diff --git a/gcc/c/c-parser.c b/gcc/c/c-parser.c
index e48760d..2efa234 100644
--- a/gcc/c/c-parser.c
+++ b/gcc/c/c-parser.c
@@ -21574,11 +21574,9 @@ c_parser_parse_rtl_body (c_parser *parser, char *start_with_pass)
       return;
     }
 
- /*  If a pass name was provided for START_WITH_PASS, run the backend
-     accordingly now, on the cfun created above, transferring
-     ownership of START_WITH_PASS.  */
-  if (start_with_pass)
-    run_rtl_passes (start_with_pass);
+ /*  Run the backend on the cfun created above, transferring ownership of
+     START_WITH_PASS.  */
+  run_rtl_passes (start_with_pass);
 }
 
 #include "gt-c-c-parser.h"
diff --git a/gcc/run-rtl-passes.c b/gcc/run-rtl-passes.c
index f65c0af..38765ebb 100644
--- a/gcc/run-rtl-passes.c
+++ b/gcc/run-rtl-passes.c
@@ -49,24 +49,31 @@ run_rtl_passes (char *initial_pass_name)
   switch_to_section (text_section);
   (*debug_hooks->assembly_start) ();
 
-  /* Pass "expand" normally sets this up.  */
+  if (initial_pass_name)
+    {
+      /* Pass "expand" normally sets this up.  */
 #ifdef INSN_SCHEDULING
-  init_sched_attrs ();
+      init_sched_attrs ();
 #endif
+      bitmap_obstack_initialize (NULL);
+      bitmap_obstack_initialize (&reg_obstack);
+      opt_pass *rest_of_compilation
+	= g->get_passes ()->get_rest_of_compilation ();
+      gcc_assert (rest_of_compilation);
+      execute_pass_list (cfun, rest_of_compilation);
 
-  bitmap_obstack_initialize (NULL);
-  bitmap_obstack_initialize (&reg_obstack);
-
-  opt_pass *rest_of_compilation
-    = g->get_passes ()->get_rest_of_compilation ();
-  gcc_assert (rest_of_compilation);
-  execute_pass_list (cfun, rest_of_compilation);
-
-  opt_pass *clean_slate = g->get_passes ()->get_clean_slate ();
-  gcc_assert (clean_slate);
-  execute_pass_list (cfun, clean_slate);
-
-  bitmap_obstack_release (&reg_obstack);
+      opt_pass *clean_slate = g->get_passes ()->get_clean_slate ();
+      gcc_assert (clean_slate);
+      execute_pass_list (cfun, clean_slate);
+      bitmap_obstack_release (&reg_obstack);
+    }
+  else
+    {
+      opt_pass *clean_slate = g->get_passes ()->get_clean_slate ();
+      gcc_assert (clean_slate);
+      execute_pass_list (cfun, clean_slate);
+    }
 
   cfun->curr_properties |= PROP_rtl;
+  free (initial_pass_name);
 }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 40a6112..87705b4 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2019-11-18  Matthew Malcomson  <matthew.malcomson@arm.com>
+
+	* gcc.dg/rtl/aarch64/unspecified-pass-error.c: New test.
+
 2019-11-18  Christophe Lyon  <christophe.lyon@linaro.org>
 
 	* lib/target-supports.exp
diff --git a/gcc/testsuite/gcc.dg/rtl/aarch64/unspecified-pass-error.c b/gcc/testsuite/gcc.dg/rtl/aarch64/unspecified-pass-error.c
new file mode 100644
index 0000000..596501e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/rtl/aarch64/unspecified-pass-error.c
@@ -0,0 +1,30 @@
+/* { dg-do compile { target aarch64-*-* } } */
+/* { dg-additional-options "-O0" } */
+
+/*
+   Ensure an __RTL function with an unspecified "startwith" pass doesn't cause
+   an assertion error on the next function.
+ */
+
+int __RTL () badfoo ()
+{
+(function "badfoo"
+  (insn-chain
+    (block 2
+      (edge-from entry (flags "FALLTHRU"))
+      (cnote 3 [bb 2] NOTE_INSN_BASIC_BLOCK)
+      (cinsn 101 (set (reg:DI x19) (reg:DI x0)))
+      (cinsn 10 (use (reg/i:SI x19)))
+      (edge-to exit (flags "FALLTHRU"))
+    ) ;; block 2
+  ) ;; insn-chain
+) ;; function "foo2"
+}
+
+/* Compile a valid C function to test the clean_state pass has been run.  */
+int
+foo_a ()
+{
+  return 200;
+}
+