PATCH] PR target/65612: Multiversioning doesn't work with DSO nor PIE

[H.J. Lu]

We shouldn't call external function, __cpu_indicator_init, while an object
is being relocated since its .got.plt section hasn't been updated.  It
works for non-PIE since no update on .got.plt section is required.  This
patch hides __cpu_indicator_init/__cpu_model from linker to force linker
to resolve __cpu_indicator_init/__cpu_model to their hidden definitions
in libgcc.a while providing backward binary compatibility.

OK for trunk, 4.9 and 4.9 branches?

Thanks.


H.J.
---
libgcc/

        PR target/65612
        * config/i386/cpuinfo.c (__cpu_model): Initialize.
        (__cpu_indicator_init@GCC_4.8.0): New.
        (__cpu_model@GCC_4.8.0): Likewise.

gcc/testsuite/

        PR target/65612
        * g++.dg/ext/mv18.C: New test.
        * g++.dg/ext/mv19.C: Likewise.
        * g++.dg/ext/mv20.C: Likewise.
---
 gcc/testsuite/g++.dg/ext/mv18.C | 7 +++++++
 gcc/testsuite/g++.dg/ext/mv19.C | 7 +++++++
 gcc/testsuite/g++.dg/ext/mv20.C | 7 +++++++
 libgcc/config/i386/cpuinfo.c    | 7 ++++++-
 4 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/ext/mv18.C
 create mode 100644 gcc/testsuite/g++.dg/ext/mv19.C
 create mode 100644 gcc/testsuite/g++.dg/ext/mv20.C

diff --git a/gcc/testsuite/g++.dg/ext/mv18.C b/gcc/testsuite/g++.dg/ext/mv18.C
new file mode 100644
index 0000000..1f024de
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/mv18.C
@@ -0,0 +1,7 @@
+/* Test case to check if Multiversioning works.  */
+/* { dg-do run { target i?86-*-* x86_64-*-* } } */
+/* { dg-require-ifunc "" }  */
+/* { dg-require-effective-target pie } */
+/* { dg-options "-O2 -fPIE -pie" } */
+
+#include "mv1.C"
diff --git a/gcc/testsuite/g++.dg/ext/mv19.C b/gcc/testsuite/g++.dg/ext/mv19.C
new file mode 100644
index 0000000..d1ea788
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/mv19.C
@@ -0,0 +1,7 @@
+/* Test case to check if Multiversioning works.  */
+/* { dg-do run { target i?86-*-* x86_64-*-* } } */
+/* { dg-require-ifunc "" }  */
+/* { dg-require-effective-target pie } */
+/* { dg-options "-O2 -fPIE -pie -march=x86-64" } */
+
+#include "mv14.C"
diff --git a/gcc/testsuite/g++.dg/ext/mv20.C b/gcc/testsuite/g++.dg/ext/mv20.C
new file mode 100644
index 0000000..98f7408
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/mv20.C
@@ -0,0 +1,7 @@
+/* Test case to check if Multiversioning works.  */
+/* { dg-do run { target i?86-*-* x86_64-*-* } } */
+/* { dg-require-ifunc "" }  */
+/* { dg-require-effective-target pie } */
+/* { dg-options "-O2 -fPIE -pie -march=x86-64" } */
+
+#include "mv15.C"
diff --git a/libgcc/config/i386/cpuinfo.c b/libgcc/config/i386/cpuinfo.c
index eaf2f10..9639c8d 100644
--- a/libgcc/config/i386/cpuinfo.c
+++ b/libgcc/config/i386/cpuinfo.c
@@ -109,7 +109,7 @@ struct __processor_model
   unsigned int __cpu_type;
   unsigned int __cpu_subtype;
   unsigned int __cpu_features[1];
-} __cpu_model;
+} __cpu_model = { };
 
 
 /* Get the specific type of AMD CPU.  */
@@ -424,3 +424,8 @@ __cpu_indicator_init (void)
 
   return 0;
 }
+
+#if defined SHARED && !defined _WIN32
+__asm__ (".symver __cpu_indicator_init, __cpu_indicator_init@GCC_4.8.0");
+__asm__ (".symver __cpu_model, __cpu_model@GCC_4.8.0");
+#endif
-- 
2.1.0