i386: Fix up handling of target attribute [PR101180]

As shown in the testcase below, if a function has multiple target attributes
(rather than a single one with one or more arguments) or if a function
gets one target attribute on one declaration and another one on another
declaration, on x86 their effect is not combined into
DECL_FUNCTION_SPECIFIC_TARGET, but instead only the last processed target
attribute wins.  aarch64 handles this right, the following patch follows
what it does, i.e. only start with target_option_default_node if
DECL_FUNCTION_SPECIFIC_TARGET is previously NULL (i.e. the first target
attribute being processed on a function) and otherwise start from the
previous DECL_FUNCTION_SPECIFIC_TARGET.

2021-11-21  Jakub Jelinek  <jakub@redhat.com>

	PR c++/101180
	* config/i386/i386-options.c (ix86_valid_target_attribute_p): If
	fndecl already has DECL_FUNCTION_SPECIFIC_TARGET, use that as base
	instead of target_option_default_node.

	* gcc.target/i386/pr101180.c: New test.

diff --git a/gcc/config/i386/i386-options.c b/gcc/config/i386/i386-options.c
index feff2584f41a2c5b7e501d3e8415b8d29708e056..a4da8331b8b7fc638bb05ca54d41e326cfecaffd 100644 (file)
--- a/gcc/config/i386/i386-options.c
+++ b/gcc/config/i386/i386-options.c
@@ -1443,8 +1443,11 @@ ix86_valid_target_attribute_p (tree fndecl,
 
   /* Initialize func_options to the default before its target options can
      be set.  */
+  tree old_target = DECL_FUNCTION_SPECIFIC_TARGET (fndecl);
+  if (old_target == NULL_TREE)
+    old_target = target_option_default_node;
   cl_target_option_restore (&func_options, &func_options_set,
-                           TREE_TARGET_OPTION (target_option_default_node));
+                           TREE_TARGET_OPTION (old_target));
 
   /* FLAGS == 1 is used for target_clones attribute.  */
   new_target

diff --git a/gcc/testsuite/gcc.target/i386/pr101180.c b/gcc/testsuite/gcc.target/i386/pr101180.c
new file mode 100644 (file)
index 0000000..1ac4cb5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr101180.c
@@ -0,0 +1,12 @@
+/* PR c++/101180 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -mno-avx -mno-crc32" } */
+
+#include <x86intrin.h>
+
+__attribute__((target ("avx"))) __attribute__((target ("crc32"))) void
+foo (__m256 *p, unsigned int *q)
+{
+  __m256 c = _mm256_and_ps (p[0], p[1]);
+  *q = __crc32b (*q, 0x55);
+}