[dpdk-dev] [PATCH v3 02/15] vhost: unify unroll pragma parameter

[Marvin Liu]

Add macro for unifying Clang/ICC/GCC unroll pragma format. Batch
functions were contained of several small loops which optimized by
compiler’s loop unrolling pragma.

Signed-off-by: Marvin Liu <yong.liu at intel.com>

diff --git a/lib/librte_vhost/Makefile b/lib/librte_vhost/Makefile
index 8623e91c0..30839a001 100644
--- a/lib/librte_vhost/Makefile
+++ b/lib/librte_vhost/Makefile
@@ -16,6 +16,24 @@ CFLAGS += -I vhost_user
 CFLAGS += -fno-strict-aliasing
 LDLIBS += -lpthread
 
+ifeq ($(RTE_TOOLCHAIN), gcc)
+ifeq ($(shell test $(GCC_VERSION) -ge 83 && echo 1), 1)
+CFLAGS += -DSUPPORT_GCC_UNROLL_PRAGMA
+endif
+endif
+
+ifeq ($(RTE_TOOLCHAIN), clang)
+ifeq ($(shell test $(CLANG_MAJOR_VERSION)$(CLANG_MINOR_VERSION) -ge 37 && echo 1), 1)
+CFLAGS += -DSUPPORT_CLANG_UNROLL_PRAGMA
+endif
+endif
+
+ifeq ($(RTE_TOOLCHAIN), icc)
+ifeq ($(shell test $(ICC_MAJOR_VERSION) -ge 16 && echo 1), 1)
+CFLAGS += -DSUPPORT_ICC_UNROLL_PRAGMA
+endif
+endif
+
 ifeq ($(CONFIG_RTE_LIBRTE_VHOST_NUMA),y)
 LDLIBS += -lnuma
 endif
diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index 884befa85..4cba8c5ef 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -39,6 +39,24 @@
 
 #define VHOST_LOG_CACHE_NR 32
 
+#ifdef SUPPORT_GCC_UNROLL_PRAGMA
+#define UNROLL_PRAGMA_PARAM "GCC unroll 4"
+#endif
+
+#ifdef SUPPORT_CLANG_UNROLL_PRAGMA
+#define UNROLL_PRAGMA_PARAM "unroll 4"
+#endif
+
+#ifdef SUPPORT_ICC_UNROLL_PRAGMA
+#define UNROLL_PRAGMA_PARAM "unroll (4)"
+#endif
+
+#ifdef UNROLL_PRAGMA_PARAM
+#define UNROLL_PRAGMA(param) _Pragma(param)
+#else
+#define UNROLL_PRAGMA(param) do {} while (0);
+#endif
+
 /**
  * Structure contains buffer address, length and descriptor index
  * from vring to do scatter RX.
-- 
2.17.1