ARM-Darwin: re-enable -momit-leaf-frame-pointer.

In r279546 I disabled all frame pointer elimination at the front-end on
ARM-Darwin (and warned about it) because before that the backend had been
silently ignoring these options. It turns out we didn't ignore
-momit-leaf-frame-pointer though, just the more general -fomit-frame-pointer.

So this re-enables passing that down to CodeGen so that everything really does
continue working as before (with better diagnostics).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@293311 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index 9bc9ae4..7e52514 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -1109,10 +1109,6 @@
                      options::OPT_fno_omit_frame_pointer, false))
       getDriver().Diag(clang::diag::warn_drv_unsupported_opt_for_target)
           << "-fomit-frame-pointer" << BoundArch;
-    if (Args.hasFlag(options::OPT_momit_leaf_frame_pointer,
-                     options::OPT_mno_omit_leaf_frame_pointer, false))
-      getDriver().Diag(clang::diag::warn_drv_unsupported_opt_for_target)
-          << "-momit-leaf-frame-pointer" << BoundArch;
   }
 
   return DAL;
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index dc3f208..30d48b7 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -3409,7 +3409,7 @@
   return false;
 }
 
-static bool mustUseFramePointerForTarget(const llvm::Triple &Triple) {
+static bool mustUseNonLeafFramePointerForTarget(const llvm::Triple &Triple) {
   switch (Triple.getArch()){
   default:
     return false;
@@ -3475,7 +3475,7 @@
   if (Arg *A = Args.getLastArg(options::OPT_fno_omit_frame_pointer,
                                options::OPT_fomit_frame_pointer))
     return A->getOption().matches(options::OPT_fno_omit_frame_pointer) ||
-           mustUseFramePointerForTarget(Triple);
+           mustUseNonLeafFramePointerForTarget(Triple);
 
   if (Args.hasArg(options::OPT_pg))
     return true;
@@ -3487,8 +3487,7 @@
                                       const llvm::Triple &Triple) {
   if (Arg *A = Args.getLastArg(options::OPT_mno_omit_leaf_frame_pointer,
                                options::OPT_momit_leaf_frame_pointer))
-    return A->getOption().matches(options::OPT_mno_omit_leaf_frame_pointer) ||
-           mustUseFramePointerForTarget(Triple);
+    return A->getOption().matches(options::OPT_mno_omit_leaf_frame_pointer);
 
   if (Args.hasArg(options::OPT_pg))
     return true;
diff --git a/test/Driver/frame-pointer-elim.c b/test/Driver/frame-pointer-elim.c
index e1d816e..e39499a 100644
--- a/test/Driver/frame-pointer-elim.c
+++ b/test/Driver/frame-pointer-elim.c
@@ -49,9 +49,9 @@
 
 // RUN: %clang -### -target armv7s-apple-ios8.0 -momit-leaf-frame-pointer %s 2>&1 | \
 // RUN:   FileCheck --check-prefix=WARN-OMIT-LEAF-7S %s
-// WARN-OMIT-LEAF-7S: warning: optimization flag '-momit-leaf-frame-pointer' is not supported for target 'armv7s'
+// WARN-OMIT-LEAF-7S-NOT: warning: optimization flag '-momit-leaf-frame-pointer' is not supported for target 'armv7s'
 // WARN-OMIT-LEAF-7S: "-mdisable-fp-elim"
-// WARN-OMIT-LEAF-7S-NOT: "-momit-leaf-frame-pointer"
+// WARN-OMIT-LEAF-7S: "-momit-leaf-frame-pointer"
 
 // On the PS4, we default to omitting the frame pointer on leaf functions
 // (OMIT_LEAF check line is above)