AArch64: Have empty HWCAPs string ignored during native feature detection

This patch makes the feature detection code for AArch64 GCC not add features
automatically when the feature had no hwcaps string to match against.

This means that -mcpu=native no longer adds feature flags such as +profile.
The behavior wasn't noticed before because at the time +profile was added a bug
was preventing any feature bits from being added by native detections.

The loop has also been changed as Jakub specified in order to avoid a memory
leak that was present in the existing code and to be slightly more efficient.

gcc/ChangeLog:

	PR target/88530
	* config/aarch64/aarch64-option-extensions.def: Document it.
	* config/aarch64/driver-aarch64.c (host_detect_local_cpu): Skip feature
	if empty hwcaps.

gcc/testsuite/ChangeLog:

	PR target/88530
	* gcc.target/aarch64/options_set_10.c: New test.

From-SVN: r269276

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f9b71975e1084e5d615711a5f5e6cca3001d22af..e7ca0e4c15efffb682f6816cc856e9d0a015e0bd 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2019-02-28  Tamar Christina  <tamar.christina@arm.com>
+
+       PR target/88530
+       * config/aarch64/aarch64-option-extensions.def: Document it.
+       * config/aarch64/driver-aarch64.c (host_detect_local_cpu): Skip feature
+       if empty hwcaps.
+
 2019-02-28  Jakub Jelinek  <jakub@redhat.com>
 
        PR c/89520

diff --git a/gcc/config/aarch64/aarch64-option-extensions.def b/gcc/config/aarch64/aarch64-option-extensions.def
index 1b2f4abbd5b850135af2cb7010921b45c03516a9..7a80b690ef23b26d81f0aa6159e5c118bb7d076c 100644 (file)
--- a/gcc/config/aarch64/aarch64-option-extensions.def
+++ b/gcc/config/aarch64/aarch64-option-extensions.def
@@ -44,7 +44,8 @@
      the extension (for example, the 'crypto' extension depends on four
      entries: aes, pmull, sha1, sha2 being present).  In that case this field
      should contain a space (" ") separated list of the strings in 'Features'
-     that are required.  Their order is not important.  */
+     that are required.  Their order is not important.  An empty string means
+     do not detect this feature during auto detection.  */
 
 /* Enabling "fp" just enables "fp".
    Disabling "fp" also disables "simd", "crypto", "fp16", "aes", "sha2",

diff --git a/gcc/config/aarch64/driver-aarch64.c b/gcc/config/aarch64/driver-aarch64.c
index 6051443d9268c0d1d4c024be8ba0731c03340e59..6f16775f47d44288c45d1bbf2cc1b59dc08528ac 100644 (file)
--- a/gcc/config/aarch64/driver-aarch64.c
+++ b/gcc/config/aarch64/driver-aarch64.c
@@ -249,27 +249,35 @@ host_detect_local_cpu (int argc, const char **argv)
        {
          for (i = 0; i < num_exts; i++)
            {
-             char *p = NULL;
-             char *feat_string
-               = concat (aarch64_extensions[i].feat_string, NULL);
+             const char *p = aarch64_extensions[i].feat_string;
+
+             /* If the feature contains no HWCAPS string then ignore it for the
+                auto detection.  */
+             if (*p == '\0')
+               continue;
+
              bool enabled = true;
 
              /* This may be a multi-token feature string.  We need
-                to match all parts, which could be in any order.
-                If this isn't a multi-token feature string, strtok is
-                just going to return a pointer to feat_string.  */
-             p = strtok (feat_string, " ");
-             while (p != NULL)
+                to match all parts, which could be in any order.  */
+             size_t len = strlen (buf);
+             do
                {
-                 if (strstr (buf, p) == NULL)
+                 const char *end = strchr (p, ' ');
+                 if (end == NULL)
+                   end = strchr (p, '\0');
+                 if (memmem (buf, len, p, end - p) == NULL)
                    {
                      /* Failed to match this token.  Turn off the
                         features we'd otherwise enable.  */
                      enabled = false;
                      break;
                    }
-                 p = strtok (NULL, " ");
+                 if (*end == '\0')
+                   break;
+                 p = end + 1;
                }
+             while (1);
 
              if (enabled)
                extension_flags |= aarch64_extensions[i].flag;
@@ -360,12 +368,12 @@ host_detect_local_cpu (int argc, const char **argv)
 not_found:
   {
    /* If detection fails we ignore the option.
-      Clean up and return empty string.  */
+      Clean up and return NULL.  */
 
     if (f)
       fclose (f);
 
-    return "";
+    return NULL;
   }
 }
 

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 8c80d5e88d1a426306038dfb6c648095aad63214..6795bfc767841d2e67a076df6b0d9bf54b5a1b32 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2019-02-28  Tamar Christina  <tamar.christina@arm.com>
+
+       PR target/88530
+       * gcc.target/aarch64/options_set_10.c: New test.
+
 2019-02-28  Paolo Carlini  <paolo.carlini@oracle.com>
 
        PR c++/89522

diff --git a/gcc/testsuite/gcc.target/aarch64/options_set_10.c b/gcc/testsuite/gcc.target/aarch64/options_set_10.c
new file mode 100644 (file)
index 0000000..5ffe83c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/options_set_10.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target "aarch64*-*-linux*" } } */
+/* { dg-additional-options "-mcpu=native" } */
+
+int main ()
+{
+  return 0;
+}
+
+/* { dg-final { scan-assembler-not {\.arch .+\+profile.*} } } */
+
+ /* Check that an empty feature string is not detected during mcpu=native.  */