Change the default target CPU for OpenBSD/i386 to i586

(cherry picked from commit cd5ab56)

Author: brad0

clang/lib/Driver/ToolChains/Arch/X86.cpp

@@ -93,13 +93,13 @@ const char *x86::getX86TargetCPU(const ArgList &Args,
     return "x86-64";
 
   switch (Triple.getOS()) {
-  case llvm::Triple::FreeBSD:
-    return "i686";
   case llvm::Triple::NetBSD:
-  case llvm::Triple::OpenBSD:
     return "i486";
   case llvm::Triple::Haiku:
+  case llvm::Triple::OpenBSD:
     return "i586";
+  case llvm::Triple::FreeBSD:
+    return "i686";
   default:
     // Fallback to p4.
     return "pentium4";

clang/test/Driver/openbsd.c

@@ -14,6 +14,11 @@
 // CHECK-PG: clang{{.*}}" "-cc1" "-triple" "i686-pc-openbsd"
 // CHECK-PG: ld{{.*}}" "-e" "__start" "--eh-frame-hdr" "-Bdynamic" "-dynamic-linker" "{{.*}}ld.so" "-nopie" "-o" "a.out" "{{.*}}gcrt0.o" "{{.*}}crtbegin.o" "{{.*}}.o" "-lcompiler_rt" "-lpthread_p" "-lc_p" "-lcompiler_rt" "{{.*}}crtend.o"
 
+// Check CPU type for i386
+// RUN: %clang -target i386-unknown-openbsd -### -c %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-i386-CPU %s
+// CHECK-i386-CPU: "-target-cpu" "i586"
+
 // Check CPU type for MIPS64
 // RUN: %clang -target mips64-unknown-openbsd -### -c %s 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHECK-MIPS64-CPU %s