[PATCH] PR target/67995: __attribute__ ((target("arch=XXX"))) enables unsupported ISA

[H.J. Lu]

When processing __attribute__ ((target("arch=XXX"))), we should clear
the ISA bits in x_ix86_isa_flags first to avoid leaking ISA from
command line.

Tested on x86-64.  OK for trunk?

Thanks.

H.J.
---
gcc/

        PR target/67995
        * config/i386/i386.c (ix86_valid_target_attribute_tree): If
        arch= is set,  clear all bits in x_ix86_isa_flags, except for
        ISA_64BIT, ABI_64, ABI_X32, and CODE16.

gcc/testsuite/

        PR target/67995
        * gcc.target/i386/pr67995-1.c: New test.
        * gcc.target/i386/pr67995-2.c: Likewise.
        * gcc.target/i386/pr67995-3.c: Likewise.
---
 gcc/config/i386/i386.c                    | 13 ++++++++++++-
 gcc/testsuite/gcc.target/i386/pr67995-1.c | 16 ++++++++++++++++
 gcc/testsuite/gcc.target/i386/pr67995-2.c | 16 ++++++++++++++++
 gcc/testsuite/gcc.target/i386/pr67995-3.c | 16 ++++++++++++++++
 4 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr67995-1.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr67995-2.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr67995-3.c

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index d0e1f4c..b0281c9 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -6145,7 +6145,18 @@ ix86_valid_target_attribute_tree (tree args,
       /* If we are using the default tune= or arch=, undo the string assigned,
         and use the default.  */
       if (option_strings[IX86_FUNCTION_SPECIFIC_ARCH])
-       opts->x_ix86_arch_string = option_strings[IX86_FUNCTION_SPECIFIC_ARCH];
+       {
+         opts->x_ix86_arch_string
+           = option_strings[IX86_FUNCTION_SPECIFIC_ARCH];
+
+         /* If arch= is set,  clear all bits in x_ix86_isa_flags,
+            except for ISA_64BIT, ABI_64, ABI_X32, and CODE16.  */
+         opts->x_ix86_isa_flags &= (OPTION_MASK_ISA_64BIT
+                                    | OPTION_MASK_ABI_64
+                                    | OPTION_MASK_ABI_X32
+                                    | OPTION_MASK_CODE16);
+
+       }
       else if (!orig_arch_specified)
        opts->x_ix86_arch_string = NULL;
 
diff --git a/gcc/testsuite/gcc.target/i386/pr67995-1.c 
b/gcc/testsuite/gcc.target/i386/pr67995-1.c
new file mode 100644
index 0000000..072b1fe
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67995-1.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=haswell" } */
+
+unsigned int
+__attribute__ ((target("arch=core2")))
+__x86_rdrand(void)
+{
+  unsigned int retries = 100;
+  unsigned int val;
+
+  while (__builtin_ia32_rdrand32_step(&val) == 0) /* { dg-error "needs isa 
option" } */
+    if (--retries == 0)
+      return 0;
+
+  return val;
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr67995-2.c 
b/gcc/testsuite/gcc.target/i386/pr67995-2.c
new file mode 100644
index 0000000..632bb63
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67995-2.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=core2" } */
+
+unsigned int
+__attribute__ ((target("arch=haswell")))
+__x86_rdrand(void)
+{
+  unsigned int retries = 100;
+  unsigned int val;
+
+  while (__builtin_ia32_rdrand32_step(&val) == 0)
+    if (--retries == 0)
+      return 0;
+
+  return val;
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr67995-3.c 
b/gcc/testsuite/gcc.target/i386/pr67995-3.c
new file mode 100644
index 0000000..11993b7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr67995-3.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=core2" } */
+
+unsigned int
+__attribute__ ((target("rdrnd")))
+__x86_rdrand(void)
+{
+  unsigned int retries = 100;
+  unsigned int val;
+
+  while (__builtin_ia32_rdrand32_step(&val) == 0)
+    if (--retries == 0)
+      return 0;
+
+  return val;
+}
-- 
2.4.3