[gcc r14-2084] i386: Sync tune_string with arch_string for target attribute arch=*

[gcc r14-2084] i386: Sync tune_string with arch_string for target attribute arch=*

[Hongyu Wang]

https://gcc.gnu.org/g:2916278d14e9ac28c361c396a67256acbebda6e8

commit r14-2084-g2916278d14e9ac28c361c396a67256acbebda6e8
Author: Hongyu Wang <hongyu.wang@intel.com>
Date:   Sun Jun 25 09:50:21 2023 +0800

    i386: Sync tune_string with arch_string for target attribute arch=*
    
    For function with target attribute arch=*, current logic will set its
    tune to -mtune from command line so all target_clones will get same
    tuning flags which would affect the performance for each clone. Override
    tune with arch if tune was not explicitly specified to get proper tuning
    flags for target_clones.
    
    gcc/ChangeLog:
    
            * config/i386/i386-options.cc (ix86_valid_target_attribute_tree):
            Override tune_string with arch_string if tune_string is not
            explicitly specified.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/i386/mvc17.c: New test.

Diff:
---
 gcc/config/i386/i386-options.cc       |  6 +++++-
 gcc/testsuite/gcc.target/i386/mvc17.c | 11 +++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/gcc/config/i386/i386-options.cc b/gcc/config/i386/i386-options.cc
index 2cb0bddcd35..7f593cebe76 100644
--- a/gcc/config/i386/i386-options.cc
+++ b/gcc/config/i386/i386-options.cc
@@ -1400,7 +1400,11 @@ ix86_valid_target_attribute_tree (tree fndecl, tree args,
       if (option_strings[IX86_FUNCTION_SPECIFIC_TUNE])
 	opts->x_ix86_tune_string
 	  = ggc_strdup (option_strings[IX86_FUNCTION_SPECIFIC_TUNE]);
-      else if (orig_tune_defaulted)
+      /* If we have explicit arch string and no tune string specified, set
+	 tune_string to NULL and later it will be overriden by arch_string
+	 so target clones can get proper optimization.  */
+      else if (option_strings[IX86_FUNCTION_SPECIFIC_ARCH]
+	       || orig_tune_defaulted)
 	opts->x_ix86_tune_string = NULL;
 
       /* If fpmath= is not set, and we now have sse2 on 32-bit, use it.  */
diff --git a/gcc/testsuite/gcc.target/i386/mvc17.c b/gcc/testsuite/gcc.target/i386/mvc17.c
new file mode 100644
index 00000000000..2c7cc2fdace
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/mvc17.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-require-ifunc "" } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-times "rep mov" 1 } } */
+
+__attribute__((target_clones("default","arch=icelake-server")))
+void
+foo (char *a, char *b, int size)
+{
+  __builtin_memcpy (a, b, size & 0x7F);
+}