[PATCH] Mark asm goto with outputs as volatile

[Andrew Pinski <apinski@marvell.com>]

The manual references asm goto as being implicitly volatile already
and that was done when asm goto could not have outputs. When outputs
were added to `asm goto`, only asm goto without outputs were still being
marked as volatile. Now some parts of GCC decide, removing the `asm goto`
is ok if the output is not used, though not updating the CFG (this happens
on both the RTL level and the gimple level). Since the biggest user of `asm goto`
is the Linux kernel and they expect them to be volatile (they use them to
copy to/from userspace), we should just mark the inline-asm as volatile.

OK? Bootstrapped and tested on x86_64-linux-gnu.

	PR middle-end/110420
	PR middle-end/103979
	PR middle-end/98619

gcc/ChangeLog:

	* gimplify.cc (gimplify_asm_expr): Mark asm with labels as volatile.

gcc/testsuite/ChangeLog:

	* gcc.c-torture/compile/asmgoto-6.c: New test.
---
 gcc/gimplify.cc                               |  7 ++++-
 .../gcc.c-torture/compile/asmgoto-6.c         | 26 +++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.c-torture/compile/asmgoto-6.c

diff --git a/gcc/gimplify.cc b/gcc/gimplify.cc
index 0e24b915b8f..dc6a00e8bd9 100644
--- a/gcc/gimplify.cc
+++ b/gcc/gimplify.cc
@@ -6935,7 +6935,12 @@ gimplify_asm_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p)
       stmt = gimple_build_asm_vec (TREE_STRING_POINTER (ASM_STRING (expr)),
 				   inputs, outputs, clobbers, labels);
 
-      gimple_asm_set_volatile (stmt, ASM_VOLATILE_P (expr) || noutputs == 0);
+      /* asm is volatile if it was marked by the user as volatile or
+	 there is no outputs or this is an asm goto.  */
+      gimple_asm_set_volatile (stmt,
+			       ASM_VOLATILE_P (expr)
+			       || noutputs == 0
+			       || labels);
       gimple_asm_set_input (stmt, ASM_INPUT_P (expr));
       gimple_asm_set_inline (stmt, ASM_INLINE_P (expr));
 
diff --git a/gcc/testsuite/gcc.c-torture/compile/asmgoto-6.c b/gcc/testsuite/gcc.c-torture/compile/asmgoto-6.c
new file mode 100644
index 00000000000..0652bd4e4e1
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/asmgoto-6.c
@@ -0,0 +1,26 @@
+
+/* { dg-do compile } */
+/* PR middle-end/110420 */
+/* PR middle-end/103979 */
+/* PR middle-end/98619 */
+/* Test that the middle-end does not remove the asm goto
+   with an output. */
+
+static int t;
+void g(void);
+
+void f(void)
+{
+  int  __gu_val;
+  asm goto("#my asm "
+     : "=&r"(__gu_val)
+     :
+     :
+     : Efault);
+  t = __gu_val;
+  g();
+Efault:
+}
+
+/* Make sure "my asm " is still in the assembly. */
+/* { dg-final { scan-assembler "my asm " } } */
-- 
2.31.1