[MIPS, committed] Tidy atomic-related failures for mips-elf

[Richard Sandiford]

Plain MIPS I testing on mips-elf has quite a few atomic-related failures,
due to the lack of LL and SC.  Fixed as below.

Tested on mips-elf, mips64-linux-gnu, and a host of others.  Applied.

Richard


gcc/testsuite/
        * lib/target-supports.exp (check_effective_target_mips_llsc): New.
        (check_effective_target_sync_int_long): Use it.
        (check_effective_target_sync_char_short): Likewise.
        * gcc.target/mips/atomic-memory-1.c: Restrict error check to mips_llsc.

Index: gcc/testsuite/lib/target-supports.exp
===================================================================
--- gcc/testsuite/lib/target-supports.exp       2012-02-05 14:34:48.000000000 
+0000
+++ gcc/testsuite/lib/target-supports.exp       2012-02-05 14:51:03.000000000 
+0000
@@ -890,6 +890,26 @@ proc check_effective_target_mips_newabi_
     } "-mabi=64"]
 }
 
+# Return true if the target is a MIPS target that has access
+# to the LL and SC instructions.
+
+proc check_effective_target_mips_llsc { } {
+    if { ![istarget mips*-*-*] } {
+       return 0
+    }
+    # Assume that these instructions are always implemented for
+    # non-elf* targets, via emulation if necessary.
+    if { ![istarget *-*-elf*] } {
+       return 1
+    }
+    # Otherwise assume LL/SC support for everything but MIPS I.
+    return [check_no_compiler_messages mips_llsc assembly {
+       #if __mips == 1
+       #error FOO
+       #endif
+    }]
+}
+
 # Return 1 if the current multilib does not generate PIC by default.
 
 proc check_effective_target_nonpic { } {
@@ -3770,7 +3790,7 @@ proc check_effective_target_sync_int_lon
             || [istarget powerpc*-*-*]
             || [istarget sparc64-*-*]
             || [istarget sparcv9-*-*]
-            || [istarget mips*-*-*] } {
+            || [check_effective_target_mips_llsc] } {
            set et_sync_int_long_saved 1
         }
     }
@@ -3800,7 +3820,7 @@ proc check_effective_target_sync_char_sh
             || [istarget powerpc*-*-*]
             || [istarget sparc64-*-*]
             || [istarget sparcv9-*-*]
-            || [istarget mips*-*-*] } {
+            || [check_effective_target_mips_llsc] } {
            set et_sync_char_short_saved 1
         }
     }
Index: gcc/testsuite/gcc.target/mips/atomic-memory-1.c
===================================================================
--- gcc/testsuite/gcc.target/mips/atomic-memory-1.c     2012-02-05 
14:34:48.000000000 +0000
+++ gcc/testsuite/gcc.target/mips/atomic-memory-1.c     2012-02-05 
14:50:33.000000000 +0000
@@ -1,6 +1,6 @@
 /* { dg-do run } */
 
-/* { dg-message "note: '__sync_nand_and_fetch' changed semantics in GCC 4.4" 
"" { target *-*-* } 0 } */
+/* { dg-message "note: '__sync_nand_and_fetch' changed semantics in GCC 4.4" 
"" { target mips_llsc } 0 } */
 
 extern void abort (void);
 extern void exit (int);