[PATCH] D15899: Add -fno-movt frontend option, to disable movt/movw on ARM

[Dimitry Andric via cfe-commits]

dim created this revision.
dim added reviewers: davide, echristo, dexonsmith.
dim added subscribers: emaste, ahatanak, cfe-commits, davide.
Herald added subscribers: rengolin, aemerson.

In rL256641, @davide turned off movt generation by default for FreeBSD.
This was because our ld is very old, and did not support the relocations
for it.  However, Ian Lepore added the support very recently, so we
would like to revert rL256641, and replace it with a new `-fno-movt`
frontend option.  This way, it can be turned off when needed.

http://reviews.llvm.org/D15899

Files:
  include/clang/Driver/Options.td
  lib/Driver/Tools.cpp
  test/Driver/arm-no-movt.c

Index: test/Driver/arm-no-movt.c
===================================================================
--- test/Driver/arm-no-movt.c
+++ test/Driver/arm-no-movt.c
@@ -4,11 +4,11 @@
 // RUN: %clang -target armv7-apple-darwin -mkernel -### %s 2>&1 \
 // RUN:    | FileCheck %s -check-prefix CHECK-KERNEL
 
-// RUN: %clang -target armv7-gnueabi-freebsd11 -### %s 2>&1 \
-// RUN:    | FileCheck %s -check-prefix CHECK-FREEBSD
+// RUN: %clang -target armv7-none-gnueabi -fno-movt -### %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-NO-MOVT
 
 // CHECK-DEFAULT-NOT: "-target-feature" "+no-movt"
 
 // CHECK-KERNEL: "-target-feature" "+no-movt"
 
-// CHECK-FREEBSD: "-target-feature" "+no-movt"
+// CHECK-NO-MOVT: "-target-feature" "+no-movt"
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -938,8 +938,8 @@
   if (Args.hasArg(options::OPT_ffixed_r9))
     Features.push_back("+reserve-r9");
 
-  // The kext and FreeBSD linkers don't know how to deal with movw/movt.
-  if (KernelOrKext || Triple.isOSFreeBSD())
+  // The kext linker doesn't know how to deal with movw/movt.
+  if (KernelOrKext || Args.hasArg(options::OPT_fno_movt))
     Features.push_back("+no-movt");
 }
 
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -1385,6 +1385,8 @@
 def marm : Flag<["-"], "marm">, Alias<mno_thumb>;
 def ffixed_r9 : Flag<["-"], "ffixed-r9">, Group<m_arm_Features_Group>,
   HelpText<"Reserve the r9 register (ARM only)">;
+def fno_movt : Flag<["-"], "fno-movt">, Group<m_arm_Features_Group>,
+  HelpText<"Disallow use of movt/movw pairs (ARM only)">;
 def mcrc : Flag<["-"], "mcrc">, Group<m_arm_Features_Group>,
   HelpText<"Allow use of CRC instructions (ARM only)">;
 def mnocrc : Flag<["-"], "mnocrc">, Group<m_arm_Features_Group>,


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