[ARM] Guard the declarations of f16 to f32 vcvt intrinsics in arm_neon.h by testing __ARM_FP

Summary:
Conversions between float and half are only available when the
taraget has the half-precision extension. Guard these intrinsics
so that they don't cause crashes in the backend.

Fixes PR27550.

Reviewers: rengolin, t.p.northover

Subscribers: cfe-commits, aemerson, t.p.northover, rengolin

Differential Revision: http://reviews.llvm.org/D19665

llvm-svn: 268047

2 files changed, 15 insertions, 2 deletions

diff --git a/clang/include/clang/Basic/arm_neon.td b/clang/include/clang/Basic/arm_neon.td
index 6641ed2edee..44325fde9f5 100644
--- a/clang/include/clang/Basic/arm_neon.td
+++ b/clang/include/clang/Basic/arm_neon.td
@@ -704,8 +704,10 @@ def VGET_LOW  : NoTestOpInst<"vget_low", "dk", "csilhfUcUsUiUlPcPs", OP_LO>;
 ////////////////////////////////////////////////////////////////////////////////
 // E.3.22 Converting vectors
 
-def VCVT_F16_F32 : SInst<"vcvt_f16_f32", "md", "Hf">;
-def VCVT_F32_F16 : SInst<"vcvt_f32_f16", "wd", "h">;
+let ArchGuard = "(__ARM_FP & 2)" in {
+  def VCVT_F16_F32 : SInst<"vcvt_f16_f32", "md", "Hf">;
+  def VCVT_F32_F16 : SInst<"vcvt_f32_f16", "wd", "h">;
+}
 
 def VCVT_S32     : SInst<"vcvt_s32", "xd",  "fQf">;
 def VCVT_U32     : SInst<"vcvt_u32", "ud",  "fQf">;
diff --git a/clang/test/Sema/arm-no-fp16.c b/clang/test/Sema/arm-no-fp16.c
new file mode 100644
index 00000000000..6443d83198c
--- /dev/null
+++ b/clang/test/Sema/arm-no-fp16.c
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple thumbv7-none-eabi %s -target-feature +neon -target-feature -fp16 -fsyntax-only -verify
+
+#include <arm_neon.h>
+
+float16x4_t test_vcvt_f16_f32(float32x4_t a) {
+  return vcvt_f16_f32(a); // expected-warning{{implicit declaration of function 'vcvt_f16_f32'}}  expected-error{{returning 'int' from a function with incompatible result type 'float16x4_t'}}
+}
+
+float32x4_t test_vcvt_f32_f16(float16x4_t a) {
+  return vcvt_f32_f16(a); // expected-warning{{implicit declaration of function 'vcvt_f32_f16'}} expected-error{{returning 'int' from a function with incompatible result type 'float32x4_t'}}
+}