[Qemu-devel] [PATCH] qemu/compiler: Wrap __attribute__((flatten)) in a macro

[Thomas Huth]

Older versions of Clang (before 3.5) and GCC (before 4.1) do not
support the "__attribute__((flatten))" yet. Since at least Clang
3.4 is still used in EPEL for RHEL7 / CentOS 7, we should not
use this attribute directly but with a wrapper macro instead.

Signed-off-by: Thomas Huth <address@hidden>
---
 fpu/softfloat.c         | 30 +++++++++++++++---------------
 include/qemu/compiler.h | 15 +++++++++++++++
 2 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 59ca356..b75ca07 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -726,7 +726,7 @@ static FloatParts addsub_floats(FloatParts a, FloatParts b, 
bool subtract,
  * IEC/IEEE Standard for Binary Floating-Point Arithmetic.
  */
 
-float16  __attribute__((flatten)) float16_add(float16 a, float16 b,
+float16 QEMU_FLATTEN float16_add(float16 a, float16 b,
                                               float_status *status)
 {
     FloatParts pa = float16_unpack_canonical(a, status);
@@ -736,7 +736,7 @@ float16  __attribute__((flatten)) float16_add(float16 a, 
float16 b,
     return float16_round_pack_canonical(pr, status);
 }
 
-float32 __attribute__((flatten)) float32_add(float32 a, float32 b,
+float32 QEMU_FLATTEN float32_add(float32 a, float32 b,
                                              float_status *status)
 {
     FloatParts pa = float32_unpack_canonical(a, status);
@@ -746,7 +746,7 @@ float32 __attribute__((flatten)) float32_add(float32 a, 
float32 b,
     return float32_round_pack_canonical(pr, status);
 }
 
-float64 __attribute__((flatten)) float64_add(float64 a, float64 b,
+float64 QEMU_FLATTEN float64_add(float64 a, float64 b,
                                              float_status *status)
 {
     FloatParts pa = float64_unpack_canonical(a, status);
@@ -756,7 +756,7 @@ float64 __attribute__((flatten)) float64_add(float64 a, 
float64 b,
     return float64_round_pack_canonical(pr, status);
 }
 
-float16 __attribute__((flatten)) float16_sub(float16 a, float16 b,
+float16 QEMU_FLATTEN float16_sub(float16 a, float16 b,
                                              float_status *status)
 {
     FloatParts pa = float16_unpack_canonical(a, status);
@@ -766,7 +766,7 @@ float16 __attribute__((flatten)) float16_sub(float16 a, 
float16 b,
     return float16_round_pack_canonical(pr, status);
 }
 
-float32 __attribute__((flatten)) float32_sub(float32 a, float32 b,
+float32 QEMU_FLATTEN float32_sub(float32 a, float32 b,
                                              float_status *status)
 {
     FloatParts pa = float32_unpack_canonical(a, status);
@@ -776,7 +776,7 @@ float32 __attribute__((flatten)) float32_sub(float32 a, 
float32 b,
     return float32_round_pack_canonical(pr, status);
 }
 
-float64 __attribute__((flatten)) float64_sub(float64 a, float64 b,
+float64 QEMU_FLATTEN float64_sub(float64 a, float64 b,
                                              float_status *status)
 {
     FloatParts pa = float64_unpack_canonical(a, status);
@@ -835,7 +835,7 @@ static FloatParts mul_floats(FloatParts a, FloatParts b, 
float_status *s)
     g_assert_not_reached();
 }
 
-float16 __attribute__((flatten)) float16_mul(float16 a, float16 b,
+float16 QEMU_FLATTEN float16_mul(float16 a, float16 b,
                                              float_status *status)
 {
     FloatParts pa = float16_unpack_canonical(a, status);
@@ -845,7 +845,7 @@ float16 __attribute__((flatten)) float16_mul(float16 a, 
float16 b,
     return float16_round_pack_canonical(pr, status);
 }
 
-float32 __attribute__((flatten)) float32_mul(float32 a, float32 b,
+float32 QEMU_FLATTEN float32_mul(float32 a, float32 b,
                                              float_status *status)
 {
     FloatParts pa = float32_unpack_canonical(a, status);
@@ -855,7 +855,7 @@ float32 __attribute__((flatten)) float32_mul(float32 a, 
float32 b,
     return float32_round_pack_canonical(pr, status);
 }
 
-float64 __attribute__((flatten)) float64_mul(float64 a, float64 b,
+float64 QEMU_FLATTEN float64_mul(float64 a, float64 b,
                                              float_status *status)
 {
     FloatParts pa = float64_unpack_canonical(a, status);
@@ -1068,7 +1068,7 @@ static FloatParts muladd_floats(FloatParts a, FloatParts 
b, FloatParts c,
     return a;
 }
 
-float16 __attribute__((flatten)) float16_muladd(float16 a, float16 b, float16 
c,
+float16 QEMU_FLATTEN float16_muladd(float16 a, float16 b, float16 c,
                                                 int flags, float_status 
*status)
 {
     FloatParts pa = float16_unpack_canonical(a, status);
@@ -1079,7 +1079,7 @@ float16 __attribute__((flatten)) float16_muladd(float16 
a, float16 b, float16 c,
     return float16_round_pack_canonical(pr, status);
 }
 
-float32 __attribute__((flatten)) float32_muladd(float32 a, float32 b, float32 
c,
+float32 QEMU_FLATTEN float32_muladd(float32 a, float32 b, float32 c,
                                                 int flags, float_status 
*status)
 {
     FloatParts pa = float32_unpack_canonical(a, status);
@@ -1090,7 +1090,7 @@ float32 __attribute__((flatten)) float32_muladd(float32 
a, float32 b, float32 c,
     return float32_round_pack_canonical(pr, status);
 }
 
-float64 __attribute__((flatten)) float64_muladd(float64 a, float64 b, float64 
c,
+float64 QEMU_FLATTEN float64_muladd(float64 a, float64 b, float64 c,
                                                 int flags, float_status 
*status)
 {
     FloatParts pa = float64_unpack_canonical(a, status);
@@ -2402,21 +2402,21 @@ static FloatParts sqrt_float(FloatParts a, float_status 
*s, const FloatFmt *p)
     return a;
 }
 
-float16 __attribute__((flatten)) float16_sqrt(float16 a, float_status *status)
+float16 QEMU_FLATTEN float16_sqrt(float16 a, float_status *status)
 {
     FloatParts pa = float16_unpack_canonical(a, status);
     FloatParts pr = sqrt_float(pa, status, &float16_params);
     return float16_round_pack_canonical(pr, status);
 }
 
-float32 __attribute__((flatten)) float32_sqrt(float32 a, float_status *status)
+float32 QEMU_FLATTEN float32_sqrt(float32 a, float_status *status)
 {
     FloatParts pa = float32_unpack_canonical(a, status);
     FloatParts pr = sqrt_float(pa, status, &float32_params);
     return float32_round_pack_canonical(pr, status);
 }
 
-float64 __attribute__((flatten)) float64_sqrt(float64 a, float_status *status)
+float64 QEMU_FLATTEN float64_sqrt(float64 a, float_status *status)
 {
     FloatParts pa = float64_unpack_canonical(a, status);
     FloatParts pr = sqrt_float(pa, status, &float64_params);
diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
index 5843812..7753ee8 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -119,6 +119,21 @@
 #define GCC_FMT_ATTR(n, m)
 #endif
 
+/*
+ * Clang 3.4 claims to be compatible with GCC 4.2, but does not have the
+ * "flatten" attribute, so we've got to handle Clang via __has_attribute here
+ */
+#if defined(__clang__) && defined(__has_attribute)
+# if __has_attribute(flatten)
+#  define QEMU_FLATTEN __attribute__((flatten))
+# endif
+#elif !defined(__clang__) && QEMU_GNUC_PREREQ(4, 1)
+# define QEMU_FLATTEN __attribute__((flatten))
+#endif
+#ifndef QEMU_FLATTEN
+# define QEMU_FLATTEN
+#endif
+
 #ifndef __has_feature
 #define __has_feature(x) 0 /* compatibility with non-clang compilers */
 #endif
-- 
1.8.3.1