Check the specific target to figure out if a constraint is a valid
register constraint. Note that we're not checking if the register itself
is valid for the constraint.

Fixes rdar://9382985


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@133226 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/arm-asm-variable.c b/test/CodeGen/arm-asm-variable.c
new file mode 100644
index 0000000..a47356a
--- /dev/null
+++ b/test/CodeGen/arm-asm-variable.c
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -triple armv7-apple-darwin9 -emit-llvm -w -o - %s | FileCheck %s
+#include <stdint.h>
+
+#define ldrex_func(p, rl, rh) \
+  __asm__ __volatile__( \
+		       "ldrexd%[_rl], %[_rh], [%[_p]]" \
+		       : [_rl] "=&r" (rl), [_rh] "=&r" (rh) \
+		       : [_p] "p" (p) : "memory")
+
+int64_t foo(int64_t v, volatile int64_t *p)
+{
+  register uint32_t rl asm("r1");
+  register uint32_t rh asm("r2");
+
+  int64_t r;
+  uint32_t t;
+
+  __asm__ __volatile__(							\
+		       "ldrexd%[_rl], %[_rh], [%[_p]]"			\
+		       : [_rl] "=&r" (rl), [_rh] "=&r" (rh)		\
+		       : [_p] "p" (p) : "memory");
+
+  // CHECK: %0 = call %0 asm sideeffect "ldrexd$0, $1, [$2]", "={r1},={r2},r,~{memory}"(i64* %tmp)
+
+  return r;
+}