Bug 1659256, add gcc version check on AArch64 optimization, r=rrelyea

Summary: As described in https://access.redhat.com/solutions/19458,
gcc version in RHEL-7 is still 4.8.x and cannot compile the newly
added aes-armv8.c. There is a version check already for 32-bit arm,
but not for AArch64. This also removes NS_USE_GCC check added in bug
1652032 in favor of the automatic detection using CC_IS_* macros.

Reviewers: rrelyea

Reviewed By: rrelyea

Subscribers: jmux, kjacobs

Bug #: 1659256

Differential Revision: https://phabricator.services.mozilla.com/D87174

--HG--
extra : rebase_source : 4c849010cabfcd483a72dc470b70e299760785a9
extra : amend_source : 366959f3de60bfe766968fd2788cfaf8d73e3c56

lib/freebl/Makefile

@@ -119,11 +119,24 @@ else
         DEFINES += -DNSS_X86
 endif
 endif
-ifdef NS_USE_GCC
 ifeq ($(CPU_ARCH),aarch64)
-    DEFINES += -DUSE_HW_AES -DUSE_HW_SHA1 -DUSE_HW_SHA2
-    EXTRA_SRCS += aes-armv8.c gcm-aarch64.c sha1-armv8.c sha256-armv8.c
-endif
+    ifdef CC_IS_CLANG
+        DEFINES += -DUSE_HW_AES -DUSE_HW_SHA1 -DUSE_HW_SHA2
+        EXTRA_SRCS += aes-armv8.c gcm-aarch64.c sha1-armv8.c sha256-armv8.c
+    else ifeq (1,$(CC_IS_GCC))
+        # GCC versions older than 4.9 don't support ARM AES. The check
+        # is done in two parts, first allows "major.minor" == "4.9",
+        # and then rejects any major versions prior to 5. Note that
+        # there has been no GCC 4.10, as it was renamed to GCC 5.
+        ifneq (,$(filter 4.9,$(word 1,$(GCC_VERSION)).$(word 2,$(GCC_VERSION))))
+            DEFINES += -DUSE_HW_AES -DUSE_HW_SHA1 -DUSE_HW_SHA2
+            EXTRA_SRCS += aes-armv8.c gcm-aarch64.c sha1-armv8.c sha256-armv8.c
+        endif
+        ifeq (,$(filter 0 1 2 3 4,$(word 1,$(GCC_VERSION))))
+            DEFINES += -DUSE_HW_AES -DUSE_HW_SHA1 -DUSE_HW_SHA2
+            EXTRA_SRCS += aes-armv8.c gcm-aarch64.c sha1-armv8.c sha256-armv8.c
+        endif
+    endif
 endif
 ifeq ($(CPU_ARCH),arm)
 ifndef NSS_DISABLE_ARM32_NEON
@@ -133,7 +146,10 @@ endif
         DEFINES += -DUSE_HW_AES -DUSE_HW_SHA1 -DUSE_HW_SHA2
         EXTRA_SRCS += aes-armv8.c sha1-armv8.c sha256-armv8.c
     else ifeq (1,$(CC_IS_GCC))
-        # Old compiler doesn't support ARM AES.
+        # GCC versions older than 4.9 don't support ARM AES. The check
+        # is done in two parts, first allows "major.minor" == "4.9",
+        # and then rejects any major versions prior to 5. Note that
+        # there has been no GCC 4.10, as it was renamed to GCC 5.
         ifneq (,$(filter 4.9,$(word 1,$(GCC_VERSION)).$(word 2,$(GCC_VERSION))))
             DEFINES += -DUSE_HW_AES -DUSE_HW_SHA1 -DUSE_HW_SHA2
             EXTRA_SRCS += aes-armv8.c sha1-armv8.c sha256-armv8.c
@@ -728,14 +744,12 @@ $(OBJDIR)/$(PROG_PREFIX)gcm-arm32-neon$(OBJ_SUFFIX): CFLAGS += -mfpu=neon$(if $(
 endif
 endif
 
-ifdef NS_USE_GCC
 ifeq ($(CPU_ARCH),aarch64)
 $(OBJDIR)/$(PROG_PREFIX)aes-armv8$(OBJ_SUFFIX): CFLAGS += -march=armv8-a+crypto
 $(OBJDIR)/$(PROG_PREFIX)gcm-aarch64$(OBJ_SUFFIX): CFLAGS += -march=armv8-a+crypto
 $(OBJDIR)/$(PROG_PREFIX)sha1-armv8$(OBJ_SUFFIX): CFLAGS += -march=armv8-a+crypto
 $(OBJDIR)/$(PROG_PREFIX)sha256-armv8$(OBJ_SUFFIX): CFLAGS += -march=armv8-a+crypto
 endif
-endif
 
 ifeq ($(CPU_ARCH),ppc)
 ifndef NSS_DISABLE_ALTIVEC