[PATCH] testsuite: fix is_amd64_regs_target

[Markus Metzger <markus dot t dot metzger at intel dot com>]

Commit

    c221b2f Testsuite: Add gdb_can_simple_compile

changed the source file name extension of the test program from .s to .c
resulting in compile fails.  This, in turn, causes is_amd64_regs_target
checks to fail.  In gdb.btrace/tailcall.exp and others, this causes the
wrong source file to be picked and the test to fail on 64-bit targets.

Change the test source from an assembly program to a C program using
inline assembly.

There is a similar case for is_aarch32_target that I have not touched as I
would not be able to test my changes.

2018-09-27  Markus Metzger  <markus.t.metzger@intel.com>

testsuite/
	* lib/gdb.exp (is_amd64_regs_target): Change assembly to C inline
	assembly.
---
 gdb/testsuite/lib/gdb.exp | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index f32abfedd52..1eea92298c4 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -2467,13 +2467,14 @@ gdb_caching_proc is_amd64_regs_target {
 	return 0
     }
 
-    set list {}
-    foreach reg \
-	{rax rbx rcx rdx rsi rdi rbp rsp r8 r9 r10 r11 r12 r13 r14 r15} {
-	    lappend list "\tincq %$reg"
-	}
+    return [gdb_can_simple_compile is_amd64_regs_target {
+	int main (void) {
+	    asm ("incq %rax");
+	    asm ("incq %r15");
 
-    return [gdb_can_simple_compile is_amd64_regs_target [join $list \n]]
+	    return 0;
+	}
+    }]
 }
 
 # Return 1 if this target is an x86 or x86-64 with -m32.
-- 
2.17.1