[PATCH][AArch64] Skip gcc.target/aarch64/assembler_arch_1.c if assembler does not support it

[Kyrill Tkachov]

Hi all,

As Christophe reported at:
https://gcc.gnu.org/ml/gcc-patches/2016-02/msg00784.html

The test gcc.target/aarch64/assembler_arch_1.c fails to assemble on older 
assemblers that
don't support the LSE architecture extension.

I'd really like to keep the test an assemble test rather than just a compile 
one since
it is extracted from a real error when building the Linux kernel, so this patch 
is
the simplest way I can think of skipping the test for older assemblers.

I've tested that the test appears UNSUPPORTED when used with a binutils that 
doesn't
support LSE and PASSes normally on latest binutils.

Do we want to have such a specialised check for assembler capabilities?
Or do we want to just let this test FAIL on older assemblers and see this 
failure go away
in the future as users/testers migrate to later binutils releases?

If such a check is desired, here's a patch that does it.

Thanks,
Kyrill

2016-02-16  Kyrylo Tkachov  <kyrylo.tkac...@arm.com>

    * lib/target-supports.exp
    (check_effective_target_aarch64_lse_assembler): New effective target
    check.
    * gcc.target/aarch64/assembler_arch_1.c: Add arch64_lse_assembler
    effective target check.

diff --git a/gcc/testsuite/gcc.target/aarch64/assembler_arch_1.c b/gcc/testsuite/gcc.target/aarch64/assembler_arch_1.c
index 901e50a178d7a4a443a5ad0abe63f624688db268..ef34e76cef9c3076a3c32e76aa7a7f658774f786 100644
--- a/gcc/testsuite/gcc.target/aarch64/assembler_arch_1.c
+++ b/gcc/testsuite/gcc.target/aarch64/assembler_arch_1.c
@@ -1,4 +1,5 @@
 /* { dg-do assemble } */
+/* { dg-require-effective-target aarch64_lse_assembler } */
 /* { dg-options "-march=armv8-a" } */
 
 /* Make sure that the function header in assembly doesn't override
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 645981a8733b68a7c37919a53b324841d2c125aa..08b4eacc26f44506d00fda58f99c203a4199856b 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -6718,6 +6718,18 @@ proc check_effective_target_aarch64_tiny { } {
     }
 }
 
+# Return 1 if the target AArch64 assembler supports the LSE extensions.
+
+proc check_effective_target_aarch64_lse_assembler { } {
+    if { [istarget aarch64*-*-*] } {
+	return [check_no_compiler_messages aarch64_lse_assembler object {
+	  __asm__ (".arch_extension lse");
+	} "-march=armv8-a+lse"]
+    } else {
+	return 0
+    }
+}
+
 proc check_effective_target_aarch64_small { } {
     if { [istarget aarch64*-*-*] } {
 	return [check_no_compiler_messages aarch64_small object {