[dpdk-dev] [PATCH v2] mk: Rework gcc version detection to permit versions newer than 4.x

[Panu Matilainen <pmatilai@redhat.com>]

Separately comparing major and minor versions becomes seriously clumsy
when with major version changes, convert the entire version string into
a numeric value (ie 4.6.0 becomes 460 and 5.0.0 becomes 500) and use
that for comparisons, eliminate unnecessary negations while at it.
This makes the comparisons simpler, more obvious and makes gcc 5.0
naturally recognized at least as capable as newest 4.x.

This three-digit scheme would run into trouble if gcc ever went to
two-digit version segments, but that hasn't happened in the last 10+
years so it seems like a safe assumption.

Signed-off-by: Panu Matilainen <pmatilai@redhat.com>
---
 lib/librte_pmd_fm10k/Makefile            |  2 +-
 lib/librte_pmd_i40e/Makefile             |  2 +-
 lib/librte_pmd_ixgbe/Makefile            |  6 +++---
 lib/librte_pmd_vmxnet3/Makefile          |  2 +-
 mk/toolchain/gcc/rte.toolchain-compat.mk | 22 ++++++++++------------
 5 files changed, 16 insertions(+), 18 deletions(-)

diff --git a/lib/librte_pmd_fm10k/Makefile b/lib/librte_pmd_fm10k/Makefile
index 986f4ef..2902d64 100644
--- a/lib/librte_pmd_fm10k/Makefile
+++ b/lib/librte_pmd_fm10k/Makefile
@@ -62,7 +62,7 @@ else
 #
 # CFLAGS for gcc
 #
-ifneq ($(shell test $(GCC_MAJOR_VERSION) -le 4 -a $(GCC_MINOR_VERSION) -le 3 && echo 1), 1)
+ifeq ($(shell test $(GCC_VERSION) -ge 440 && echo 1), 1)
 CFLAGS     += -Wno-deprecated
 endif
 CFLAGS_BASE_DRIVER = -Wno-unused-parameter -Wno-unused-value
diff --git a/lib/librte_pmd_i40e/Makefile b/lib/librte_pmd_i40e/Makefile
index 9a0eec8..484379a 100644
--- a/lib/librte_pmd_i40e/Makefile
+++ b/lib/librte_pmd_i40e/Makefile
@@ -69,7 +69,7 @@ CFLAGS_BASE_DRIVER += -Wno-pointer-to-int-cast
 CFLAGS_BASE_DRIVER += -Wno-format-nonliteral
 CFLAGS_BASE_DRIVER += -Wno-format-security
 
-ifeq ($(shell test $(GCC_MAJOR_VERSION) -ge 4 -a $(GCC_MINOR_VERSION) -ge 4 && echo 1), 1)
+ifeq ($(shell test $(GCC_VERSION) -ge 440 && echo 1), 1)
 CFLAGS_BASE_DRIVER += -Wno-unused-but-set-variable
 endif
 
diff --git a/lib/librte_pmd_ixgbe/Makefile b/lib/librte_pmd_ixgbe/Makefile
index 0279f8c..ab56cbf 100644
--- a/lib/librte_pmd_ixgbe/Makefile
+++ b/lib/librte_pmd_ixgbe/Makefile
@@ -60,18 +60,18 @@ else
 #
 # CFLAGS for gcc
 #
-ifneq ($(shell test $(GCC_MAJOR_VERSION) -le 4 -a $(GCC_MINOR_VERSION) -le 3 && echo 1), 1)
+ifeq ($(shell test $(GCC_VERSION) -ge 440 && echo 1), 1)
 CFLAGS     += -Wno-deprecated
 endif
 CFLAGS_BASE_DRIVER = -Wno-unused-parameter -Wno-unused-value
 CFLAGS_BASE_DRIVER += -Wno-strict-aliasing -Wno-format-extra-args
 
-ifeq ($(shell test $(GCC_MAJOR_VERSION) -ge 4 -a $(GCC_MINOR_VERSION) -ge 6 && echo 1), 1)
+ifeq ($(shell test $(GCC_VERSION) -ge 460 && echo 1), 1)
 CFLAGS_ixgbe_common.o += -Wno-unused-but-set-variable
 CFLAGS_ixgbe_x550.o += -Wno-unused-but-set-variable -Wno-maybe-uninitialized
 endif
 
-ifeq ($(shell test $(GCC_MAJOR_VERSION) -le 4 -a $(GCC_MINOR_VERSION) -le 6 && echo 1), 1)
+ifeq ($(shell test $(GCC_VERSION) -le 460 && echo 1), 1)
 CFLAGS_ixgbe_x550.o += -Wno-uninitialized
 CFLAGS_ixgbe_phy.o += -Wno-uninitialized
 endif
diff --git a/lib/librte_pmd_vmxnet3/Makefile b/lib/librte_pmd_vmxnet3/Makefile
index 93e5580..9dda0a7 100644
--- a/lib/librte_pmd_vmxnet3/Makefile
+++ b/lib/librte_pmd_vmxnet3/Makefile
@@ -56,7 +56,7 @@ else
 #
 # CFLAGS for gcc
 #
-ifneq ($(shell test $(GCC_MAJOR_VERSION) -le 4 -a $(GCC_MINOR_VERSION) -le 3 && echo 1), 1)
+ifeq ($(shell test $(GCC_VERSION) -ge 440 && echo 1), 1)
 CFLAGS     += -Wno-deprecated
 endif
 CFLAGS_BASE_DRIVER = -Wno-unused-parameter -Wno-unused-value
diff --git a/mk/toolchain/gcc/rte.toolchain-compat.mk b/mk/toolchain/gcc/rte.toolchain-compat.mk
index e40e103..a867559 100644
--- a/mk/toolchain/gcc/rte.toolchain-compat.mk
+++ b/mk/toolchain/gcc/rte.toolchain-compat.mk
@@ -38,17 +38,15 @@
 
 #find out GCC version
 
-GCC_MAJOR_VERSION = $(shell $(CC) -dumpversion | cut -f1 -d.)
+GCC_VERSION = $(subst .,,$(shell $(CC) -dumpversion))
 
-# if GCC is not 4.x
-ifneq ($(GCC_MAJOR_VERSION),4)
+# if GCC is older than 4.x
+ifeq ($(shell test $(GCC_VERSION) -lt 400 && echo 1), 1)
 	MACHINE_CFLAGS =
-$(warning You are not using GCC 4.x. This is neither supported, nor tested.)
+$(warning You are using GCC < 4.x. This is neither supported, nor tested.)
 
 
 else
-	GCC_MINOR_VERSION = $(shell $(CC) -dumpversion | cut -f2 -d.)
-
 # GCC graceful degradation
 # GCC 4.2.x - added support for generic target
 # GCC 4.3.x - added support for core2, ssse3, sse4.1, sse4.2
@@ -57,18 +55,18 @@ else
 # GCC 4.6.x - added support for corei7, corei7-avx
 # GCC 4.7.x - added support for fsgsbase, rdrnd, f16c, core-avx-i, core-avx2
 
-	ifeq ($(shell test $(GCC_MINOR_VERSION) -le 7 && echo 1), 1)
+	ifeq ($(shell test $(GCC_VERSION) -le 470 && echo 1), 1)
 		MACHINE_CFLAGS := $(patsubst -march=core-avx-i,-march=corei7-avx,$(MACHINE_CFLAGS))
 		MACHINE_CFLAGS := $(patsubst -march=core-avx2,-march=core-avx2,$(MACHINE_CFLAGS))
 	endif
-	ifeq ($(shell test $(GCC_MINOR_VERSION) -lt 6 && echo 1), 1)
+	ifeq ($(shell test $(GCC_VERSION) -lt 460 && echo 1), 1)
 		MACHINE_CFLAGS := $(patsubst -march=corei7-avx,-march=core2 -maes -mpclmul -mavx,$(MACHINE_CFLAGS))
 		MACHINE_CFLAGS := $(patsubst -march=corei7,-march=core2 -maes -mpclmul,$(MACHINE_CFLAGS))
 	endif
-	ifeq ($(shell test $(GCC_MINOR_VERSION) -lt 5 && echo 1), 1)
+	ifeq ($(shell test $(GCC_VERSION) -lt 450 && echo 1), 1)
 		MACHINE_CFLAGS := $(patsubst -march=atom,-march=core2 -mssse3,$(MACHINE_CFLAGS))
 	endif
-	ifeq ($(shell test $(GCC_MINOR_VERSION) -lt 4 && echo 1), 1)
+	ifeq ($(shell test $(GCC_VERSION) -lt 440 && echo 1), 1)
 		MACHINE_CFLAGS := $(filter-out -mavx -mpclmul -maes,$(MACHINE_CFLAGS))
 		ifneq ($(findstring SSE4_2, $(CPUFLAGS)),)
 			MACHINE_CFLAGS += -msse4.2
@@ -77,12 +75,12 @@ else
 			MACHINE_CFLAGS += -msse4.1
 		endif
 	endif
-	ifeq ($(shell test $(GCC_MINOR_VERSION) -lt 3 && echo 1), 1)
+	ifeq ($(shell test $(GCC_VERSION) -lt 430 && echo 1), 1)
 		MACHINE_CFLAGS := $(filter-out -msse% -mssse%,$(MACHINE_CFLAGS))
 		MACHINE_CFLAGS := $(patsubst -march=core2,-march=generic,$(MACHINE_CFLAGS))
 		MACHINE_CFLAGS += -msse3
 	endif
-	ifeq ($(shell test $(GCC_MINOR_VERSION) -lt 2 && echo 1), 1)
+	ifeq ($(shell test $(GCC_VERSION) -lt 420 && echo 1), 1)
 		MACHINE_CFLAGS := $(filter-out -march% -mtune% -msse%,$(MACHINE_CFLAGS))
 	endif
 endif
-- 
2.1.0