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Add -fno-movt frontend option, to disable movt/movw on ARM 

Summary:
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.

Reviewers: dexonsmith, echristo, emaste, davide

Subscribers: andrew, aemerson, rengolin, davide, cfe-commits, ahatanak, emaste

Differential Revision: http://reviews.llvm.org/D15899

llvm-svn: 256920
This commit is contained in:
Dimitry Andric 2016-01-06 07:42:18 +00:00
parent 29a50bccb9
commit 0810739d4c
3 changed files with 7 additions and 5 deletions
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2
clang/include/clang/Driver/Options.td
View File

@ -1385,6 +1385,8 @@ def mno_restrict_it: Flag<["-"], "mno-restrict-it">, Group<m_arm_Features_Group>
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 mno_movt : Flag<["-"], "mno-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>,

4
clang/lib/Driver/Tools.cpp
View File

@ -938,8 +938,8 @@ static void getARMTargetFeatures(const ToolChain &TC,
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_mno_movt))
Features.push_back("+no-movt");
}

6
clang/test/Driver/arm-no-movt.c
View File

@ -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 -mno-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"