runtime: rewrite lfstack packing/unpacking to look more like that in Go

    Reviewed-on: https://go-review.googlesource.com/13037

From-SVN: r228057

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index f21c43a8c6d8ba7d8adf08d01d862dca57c16964..1ea55554fba1004c934ebb09353f8a44c6679ad2 100644 (file)
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-e069d4417a692c1261df99fe3323277e1a0193d2
+2087b95180caea3477647c449772b7fecc01a71c
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

diff --git a/libgo/runtime/lfstack.goc b/libgo/runtime/lfstack.goc
index 060a0cc5941be71d295c8fc7ba39e407618fa6fa..9eb80d900f92292a0e986f98b73831f40307cb9f 100644 (file)
--- a/libgo/runtime/lfstack.goc
+++ b/libgo/runtime/lfstack.goc
@@ -9,25 +9,41 @@ package runtime
 #include "arch.h"
 
 #if __SIZEOF_POINTER__ == 8
-// Amd64 uses 48-bit virtual addresses, 47-th bit is used as kernel/user flag.
-// So we use 17msb of pointers as ABA counter.
-# define PTR_BITS 47
-#else
-# define PTR_BITS 32
-#endif
-#define PTR_MASK ((1ull<<PTR_BITS)-1)
-#define CNT_MASK (0ull-1)
-
-#if __SIZEOF_POINTER__ == 8 && (defined(__sparc__) || (defined(__sun__) && defined(__amd64__)))
 // SPARC64 and Solaris on AMD64 uses all 64 bits of virtual addresses.
 // Use low-order three bits as ABA counter.
 // http://docs.oracle.com/cd/E19120-01/open.solaris/816-5138/6mba6ua5p/index.html
-#undef PTR_BITS
-#undef CNT_MASK
-#undef PTR_MASK
-#define PTR_BITS 0
-#define CNT_MASK 7
-#define PTR_MASK ((0ull-1)<<3)
+# if defined(__sparc__) || (defined(__sun__) && defined(__amd64__))
+static inline uint64 lfPack(LFNode *node, uintptr cnt) {
+       return ((uint64)(node)) | ((cnt)&7);
+}
+static inline LFNode* lfUnpack(uint64 val) {
+       return (LFNode*)(val&~7);
+}
+# else
+#  if defined(__aarch64__)
+// Depending on the kernel options, pointers on arm64 can have up to 48 significant
+// bits (see https://www.kernel.org/doc/Documentation/arm64/memory.txt).
+#   define PTR_BITS 48
+#  else
+// Amd64 uses 48-bit virtual addresses, 47-th bit is used as kernel/user flag.
+// So we use 17msb of pointers as ABA counter.
+#   define PTR_BITS 47
+#  endif
+# endif
+# define CNT_BITS (64 - PTR_BITS + 3)
+static inline uint64 lfPack(LFNode *node, uintptr cnt) {
+       return ((uint64)(node)<<(64-PTR_BITS)) | (cnt&(((1<<CNT_BITS)-1)));
+}
+static inline LFNode* lfUnpack(uint64 val) {
+       return (LFNode*)((val >> CNT_BITS) << 3);
+}
+#else
+static inline uint64 lfPack(LFNode *node, uintptr cnt) {
+       return ((uint64)(uintptr)(node)<<32) | cnt;
+}
+static inline LFNode* lfUnpack(uint64 val) {
+       return (LFNode*)(uintptr)(val >> 32);
+}
 #endif
 
 void
@@ -35,16 +51,16 @@ runtime_lfstackpush(uint64 *head, LFNode *node)
 {
        uint64 old, new;
 
-       if((uintptr)node != ((uintptr)node&PTR_MASK)) {
+       if(node != lfUnpack(lfPack(node, 0))) {
                runtime_printf("p=%p\n", node);
                runtime_throw("runtime_lfstackpush: invalid pointer");
        }
 
        node->pushcnt++;
-       new = (uint64)(uintptr)node|(((uint64)node->pushcnt&CNT_MASK)<<PTR_BITS);
+       new = lfPack(node, node->pushcnt);
        for(;;) {
                old = runtime_atomicload64(head);
-               node->next = (LFNode*)(uintptr)(old&PTR_MASK);
+               node->next = lfUnpack(old);
                if(runtime_cas64(head, old, new))
                        break;
        }
@@ -60,11 +76,11 @@ runtime_lfstackpop(uint64 *head)
                old = runtime_atomicload64(head);
                if(old == 0)
                        return nil;
-               node = (LFNode*)(uintptr)(old&PTR_MASK);
+               node = lfUnpack(old);
                node2 = runtime_atomicloadp(&node->next);
                new = 0;
                if(node2 != nil)
-                       new = (uint64)(uintptr)node2|(((uint64)node2->pushcnt&CNT_MASK)<<PTR_BITS);
+                       new = lfPack(node2, node2->pushcnt);
                if(runtime_cas64(head, old, new))
                        return node;
        }