exec: Cache TARGET_PAGE_MASK for TARGET_PAGE_BITS_VARY

This eliminates a set of runtime shifts.  It turns out that we
require TARGET_PAGE_MASK more often than TARGET_PAGE_SIZE, so
redefine TARGET_PAGE_SIZE based on TARGET_PAGE_MASK instead of
the other way around.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

exec-vary.c

@@ -96,6 +96,7 @@ void finalize_target_page_bits(void)
     if (init_target_page.bits == 0) {
         init_target_page.bits = TARGET_PAGE_BITS_MIN;
     }
+    init_target_page.mask = (target_long)-1 << init_target_page.bits;
     init_target_page.decided = true;
 
     /*

include/exec/cpu-all.h

@@ -213,6 +213,7 @@ static inline void stl_phys_notdirty(AddressSpace *as, hwaddr addr, uint32_t val
 typedef struct {
     bool decided;
     int bits;
+    target_long mask;
 } TargetPageBits;
 #if defined(CONFIG_ATTRIBUTE_ALIAS) || !defined(IN_EXEC_VARY)
 extern const TargetPageBits target_page;
@@ -221,15 +222,18 @@ extern TargetPageBits target_page;
 #endif
 #ifdef CONFIG_DEBUG_TCG
 #define TARGET_PAGE_BITS   ({ assert(target_page.decided); target_page.bits; })
+#define TARGET_PAGE_MASK   ({ assert(target_page.decided); target_page.mask; })
 #else
 #define TARGET_PAGE_BITS   target_page.bits
+#define TARGET_PAGE_MASK   target_page.mask
 #endif
+#define TARGET_PAGE_SIZE   (-(int)TARGET_PAGE_MASK)
 #else
 #define TARGET_PAGE_BITS_MIN TARGET_PAGE_BITS
+#define TARGET_PAGE_SIZE   (1 << TARGET_PAGE_BITS)
+#define TARGET_PAGE_MASK   ((target_long)-1 << TARGET_PAGE_BITS)
 #endif
 
-#define TARGET_PAGE_SIZE (1 << TARGET_PAGE_BITS)
-#define TARGET_PAGE_MASK ((target_long)-1 << TARGET_PAGE_BITS)
 #define TARGET_PAGE_ALIGN(addr) ROUND_UP((addr), TARGET_PAGE_SIZE)
 
 /* Using intptr_t ensures that qemu_*_page_mask is sign-extended even