[PATCH, Testsuite] Add new effective target arm_prefer_ldrd_strd

[Greta Yorsh]

In the testsuite, distinguish between arm targets that prefer LDRD/STRD and
arm targets that prefer LDM/STM. This patch adds a new effective target test
and updates documentation accordingly.

Ok for trunk?

Thanks,
Greta

ChangeLog

gcc/testsuite/

2012-09-13  Greta Yorsh  <greta.yo...@arm.com>

        * gcc.target/arm/target-supports.exp
(check_effective_target_arm_prefer_ldrd_strd): New procedure.

gcc/

2012-09-13  Greta Yorsh  <greta.yo...@arm.com>

        * doc/sourcebuild.texi: Document new effective target keyword
        arm_prefer_ldrd_strd.
diff --git a/gcc/doc/sourcebuild.texi b/gcc/doc/sourcebuild.texi
index 055567b..b80ee02 100644
--- a/gcc/doc/sourcebuild.texi
+++ b/gcc/doc/sourcebuild.texi
@@ -1552,6 +1552,11 @@ ARM target generates Thumb-2 code for @code{-mthumb}.
 @item arm_vfp_ok
 ARM target supports @code{-mfpu=vfp -mfloat-abi=softfp}.
 Some multilibs may be incompatible with these options.
+
+@item arm_prefer_ldrd_strd
+ARM target prefers @code{LDRD} and @code{STRD} instructions over
+@code{LDM} and @code{STM} instructions.
+
 @end table
 
 @subsubsection MIPS-specific attributes
diff --git a/gcc/testsuite/lib/target-supports.exp 
b/gcc/testsuite/lib/target-supports.exp
index 8f793b7..4bf2424 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -2462,6 +2462,18 @@ proc check_effective_target_arm_iwmmxt_ok { } {
     }
 }
 
+# Return true if LDRD/STRD instructions are prefered over LDM/STM instructions
+# for an ARM target.
+proc check_effective_target_arm_prefer_ldrd_strd { } {
+    if { ![check_effective_target_arm32] } {
+      return 0;
+    }
+
+    return [check_no_messages_and_pattern arm_prefer_ldrd_strd "strd\tr" 
assembly {
+        void foo (int *p) { p[0] = 1; p[1] = 0;}
+    }  "-O2 -mthumb" ]
+}
+
 # Return 1 if this is a PowerPC target with floating-point registers.
 
 proc check_effective_target_powerpc_fprs { } {