i386: Use __seg_gs qualifiers in PTR_{MANGLE,DEMANGLE}() macros

 Use __seg_gs named address space qualifiers in PTR_MANGLE() and
 PTR_DEMANGLE() macros to access the pointer_guard field in the TCB.
 
 This change allows the compiler to eliminate redundant reads of
 the variable, reducing the number of reads from 105 to 94 and
 decreasing the text size of the library by 280 bytes.
 
 While at it, fix a few trivial whitespace issues as well
 
 Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
 Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
 

diff --git a/sysdeps/unix/sysv/linux/i386/pointer_guard.h b/sysdeps/unix/sysv/linux/i386/pointer_guard.h
index ae27c82a62e8361d4a41f7775b8eb296397a705a..0162178f470ec3332567935d033d29315c9edb4c 100644 (file)
--- a/sysdeps/unix/sysv/linux/i386/pointer_guard.h
+++ b/sysdeps/unix/sysv/linux/i386/pointer_guard.h
@@ -28,21 +28,24 @@
 # include <sysdeps/generic/pointer_guard.h>
 #else
 # ifdef __ASSEMBLER__
-#  define PTR_MANGLE(reg)       xorl %gs:POINTER_GUARD, reg;                  \
-                                roll $9, reg
-#  define PTR_DEMANGLE(reg)     rorl $9, reg;                                 \
-                                xorl %gs:POINTER_GUARD, reg
+#  define PTR_MANGLE(reg)      xorl %gs:POINTER_GUARD, reg;                  \
+                               roll $9, reg
+#  define PTR_DEMANGLE(reg)    rorl $9, reg;                                 \
+                               xorl %gs:POINTER_GUARD, reg
 # else
-#  define PTR_MANGLE(var)       asm ("xorl %%gs:%c2, %0\n"                    \
-                                     "roll $9, %0"                            \
-                                     : "=r" (var)                             \
-                                     : "0" (var),                             \
-                                       "i" (POINTER_GUARD))
-#  define PTR_DEMANGLE(var)     asm ("rorl $9, %0\n"                          \
-                                     "xorl %%gs:%c2, %0"                      \
-                                     : "=r" (var)                             \
-                                     : "0" (var),                             \
-                                       "i" (POINTER_GUARD))
+#  include <tls.h>
+#  define PTR_MANGLE(var) do                                                 \
+    {                                                                        \
+      (var) = (__typeof (var)) ((uintptr_t) (var)                            \
+                               ^ ((tcbhead_t __seg_gs *)0)->pointer_guard);  \
+      asm ("roll $9, %0" : "+r" (var));                                              \
+    } while (0)
+#  define PTR_DEMANGLE(var) do                                               \
+    {                                                                        \
+      asm ("rorl $9, %0" : "+r" (var));                                              \
+      (var) = (__typeof (var)) ((uintptr_t) (var)                            \
+                               ^ ((tcbhead_t __seg_gs *)0)->pointer_guard);  \
+    } while (0)
 # endif
 #endif