- // 0xCD byte (interrupt) dead, so the marker doesn't effect anything.
-#ifdef __x86_64__
- ((unsigned char*)RetAddr)[0] = (2 | (4 << 3) | (3 << 6));
+ // 0xCE byte (interrupt) dead, so the marker doesn't effect anything.
+#if defined (X86_64_JIT)
+ // If the target address is within 32-bit range of the stub, use a
+ // PC-relative branch instead of loading the actual address. (This is
+ // considerably shorter than the 64-bit immediate load already there.)
+ // We assume here intptr_t is 64 bits.
+ intptr_t diff = NewVal-RetAddr+7;
+ if (diff >= -2147483648LL && diff <= 2147483647LL) {
+ *(unsigned char*)(RetAddr-0xc) = 0xE9;
+ *(intptr_t *)(RetAddr-0xb) = diff & 0xffffffff;
+ } else {
+ *(intptr_t *)(RetAddr - 0xa) = NewVal;
+ ((unsigned char*)RetAddr)[0] = (2 | (4 << 3) | (3 << 6));
+ }
+ sys::ValgrindDiscardTranslations((void*)(RetAddr-0xc), 0xd);