Detect hwcap flags needed for runtime detection on ARM Linux

This allows us to provide useful warning messages from cmake or
configure if the system headers don't provide the necessary flags to do
runtime detection.

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 56b4a839c5c7afabd2fa0dd294d1af3a4cac6785..dd174a3dff83fdd25ab4baff58c27621672f9474 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -649,6 +649,34 @@ endif()
 if(WITH_OPTIM)
     if(BASEARCH_ARM_FOUND)
         add_definitions(-DARM_FEATURES)
+        if(${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
+            check_c_source_compiles(
+                "#include <sys/auxv.h>
+                int main() {
+                    return (getauxval(AT_HWCAP2) & HWCAP2_CRC32);
+                }"
+                ARM_AUXV_HAS_CRC32
+            )
+            if(ARM_AUXV_HAS_CRC32)
+                add_definitions(-DARM_AUXV_HAS_CRC32)
+            else()
+                message(STATUS "HWCAP2_CRC32 not present in sys/auxv.h; cannot detect support at runtime.")
+            endif()
+            if(NOT "${ARCH}" MATCHES "aarch64")
+                check_c_source_compiles(
+                    "#include <sys/auxv.h>
+                    int main() {
+                      return (getauxval(AT_HWCAP) & HWCAP_NEON);
+                    }"
+                    ARM_AUXV_HAS_NEON
+                )
+                if(ARM_AUXV_HAS_NEON)
+                    add_definitions(-DARM_AUXV_HAS_NEON)
+                else()
+                    message(STATUS "HWCAP_NEON not present in sys/auxv.h; cannot detect support at runtime.")
+                endif()
+            endif()
+        endif()
         list(APPEND ZLIB_ARCH_HDRS ${ARCHDIR}/arm.h)
         list(APPEND ZLIB_ARCH_SRCS ${ARCHDIR}/armfeature.c)
         if(WITH_ACLE AND NOT MSVC)

diff --git a/arch/arm/armfeature.c b/arch/arm/armfeature.c
index cea19e614e36cfc34671ed2fcc956bc97a277189..e8fcc1e5ea7956da1d40ed2953856a1351cb38c4 100644 (file)
--- a/arch/arm/armfeature.c
+++ b/arch/arm/armfeature.c
@@ -14,7 +14,7 @@
 #endif
 
 static int arm_has_crc32() {
-#if defined(__linux__) && defined(HWCAP2_CRC32)
+#if defined(__linux__) && defined(ARM_AUXV_HAS_CRC32)
     return (getauxval(AT_HWCAP2) & HWCAP2_CRC32) != 0 ? 1 : 0;
 #elif defined(__FreeBSD__) && defined(__aarch64__)
     return getenv("QEMU_EMULATING") == NULL
@@ -34,7 +34,7 @@ static int arm_has_crc32() {
 /* AArch64 has neon. */
 #if !defined(__aarch64__) && !defined(_M_ARM64)
 static inline int arm_has_neon() {
-#if defined(__linux__) && defined(HWCAP_NEON)
+#if defined(__linux__) && defined(ARM_AUXV_HAS_NEON)
     return (getauxval(AT_HWCAP) & HWCAP_NEON) != 0 ? 1 : 0;
 #elif defined(__APPLE__)
     int hasneon;

diff --git a/configure b/configure
index aafaa06ac5df6ae78ef20ec5353fd226d05ed764..89388be0cd043c6e298d43361345ee76d560516c 100755 (executable)
--- a/configure
+++ b/configure
@@ -524,6 +524,14 @@ else
   esac
 fi
 
+# Simplify some later conditionals
+case "$uname" in
+Linux* | linux*)
+  LINUX=1 ;;
+*)
+  LINUX=0 ;;
+esac
+
 # destination names for shared library if not defined above
 SHAREDLIB=${SHAREDLIB-"${LIBNAME}$shared_ext"}
 SHAREDLIBV=${SHAREDLIBV-"${LIBNAME}$shared_ext.$VER"}
@@ -1265,6 +1273,34 @@ case "${ARCH}" in
             SFLAGS="${SFLAGS} -DARM_FEATURES"
             ARCH_STATIC_OBJS="${ARCH_STATIC_OBJS} armfeature.o"
             ARCH_SHARED_OBJS="${ARCH_SHARED_OBJS} armfeature.lo"
+
+            if test $LINUX -eq 1; then
+                cat > $test.c <<EOF
+#include <sys/auxv.h>
+int main() {
+    return (getauxval(AT_HWCAP2) & HWCAP2_CRC32);
+}
+EOF
+                if try $CC -c $CFLAGS $test.c; then
+                    CFLAGS="${CFLAGS} -DARM_AUXV_HAS_CRC32"
+                    SFLAGS="${SFLAGS} -DARM_AUXV_HAS_CRC32"
+                else
+                    echo "HWCAP2_CRC32 not present in sys/auxv.h; cannot detect support at runtime." | tee -a configure.log
+                fi
+
+                cat > $test.c <<EOF
+#include <sys/auxv.h>
+int main() {
+    return (getauxval(AT_HWCAP) & HWCAP_NEON);
+}
+EOF
+                if try $CC -c $CFLAGS $test.c; then
+                    CFLAGS="${CFLAGS} -DARM_AUXV_HAS_NEON"
+                    SFLAGS="${SFLAGS} -DARM_AUXV_HAS_NEON"
+                else
+                    echo "HWCAP_NEON not present in sys/auxv.h; cannot detect support at runtime." | tee -a configure.log
+                fi
+            fi
         fi
 
         cat > $test.c << EOF
@@ -1405,6 +1441,21 @@ EOF
             ARCH_STATIC_OBJS="${ARCH_STATIC_OBJS} armfeature.o"
             ARCH_SHARED_OBJS="${ARCH_SHARED_OBJS} armfeature.lo"
 
+            if test $LINUX -eq 1; then
+                cat > $test.c <<EOF
+#include <sys/auxv.h>
+int main() {
+    return (getauxval(AT_HWCAP2) & HWCAP2_CRC32);
+}
+EOF
+                if try $CC -c $CFLAGS $test.c; then
+                    CFLAGS="${CFLAGS} -DARM_AUXV_HAS_CRC32"
+                    SFLAGS="${SFLAGS} -DARM_AUXV_HAS_CRC32"
+                else
+                    echo "HWCAP2_CRC32 not present in sys/auxv.h; cannot detect support at runtime." | tee -a configure.log
+                fi
+            fi
+
             if test $buildacle -eq 1; then
                 if test $native -eq 0; then
                     ARCH="${ARCH}+crc"