# HG changeset patch
# User Doug Simon <doug.simon@oracle.com>
# Date 1417803849 -3600
# Node ID 0dac22d266d885682ce6acc5878be0160866f1f5
# Parent  d5d1fbe270e9a9a92f1a1078364408b3786b9c31
always try decode both types of AMD64 safepoint patterns (i.e., near and far) when testing a PC for being a safepoint

diff -r d5d1fbe270e9 -r 0dac22d266d8 src/cpu/x86/vm/nativeInst_x86.hpp
--- a/src/cpu/x86/vm/nativeInst_x86.hpp	Fri Dec 05 19:13:26 2014 +0100
+++ b/src/cpu/x86/vm/nativeInst_x86.hpp	Fri Dec 05 19:24:09 2014 +0100
@@ -562,26 +562,24 @@
                                                           (ubyte_at(0) & 0xF0) == 0x70;  /* short jump */ }
 inline bool NativeInstruction::is_safepoint_poll() {
 #ifdef AMD64
-  if (Assembler::is_polling_page_far()) {
-    // two cases, depending on the choice of the base register in the address.
-    if (((ubyte_at(0) & NativeTstRegMem::instruction_rex_prefix_mask) == NativeTstRegMem::instruction_rex_prefix &&
-         ubyte_at(1) == NativeTstRegMem::instruction_code_memXregl &&
-         (ubyte_at(2) & NativeTstRegMem::modrm_mask) == NativeTstRegMem::modrm_reg) ||
-        ubyte_at(0) == NativeTstRegMem::instruction_code_memXregl &&
-        (ubyte_at(1) & NativeTstRegMem::modrm_mask) == NativeTstRegMem::modrm_reg) {
-      return true;
-    } else {
-      return false;
-    }
-  } else {
-    if (ubyte_at(0) == NativeTstRegMem::instruction_code_memXregl &&
-        ubyte_at(1) == 0x05) { // 00 rax 101
-      address fault = addr_at(6) + int_at(2);
-      return os::is_poll_address(fault);
-    } else {
-      return false;
-    }
+  // Try decoding a near safepoint first:
+  if (ubyte_at(0) == NativeTstRegMem::instruction_code_memXregl &&
+      ubyte_at(1) == 0x05) { // 00 rax 101
+    address fault = addr_at(6) + int_at(2);
+    NOT_GRAAL(assert(!Assembler::is_polling_page_far(), "unexpected poll encoding");)
+    return os::is_poll_address(fault);
   }
+  // Now try decoding a far safepoint:
+  // two cases, depending on the choice of the base register in the address.
+  if (((ubyte_at(0) & NativeTstRegMem::instruction_rex_prefix_mask) == NativeTstRegMem::instruction_rex_prefix &&
+       ubyte_at(1) == NativeTstRegMem::instruction_code_memXregl &&
+       (ubyte_at(2) & NativeTstRegMem::modrm_mask) == NativeTstRegMem::modrm_reg) ||
+      ubyte_at(0) == NativeTstRegMem::instruction_code_memXregl &&
+      (ubyte_at(1) & NativeTstRegMem::modrm_mask) == NativeTstRegMem::modrm_reg) {
+    NOT_GRAAL(assert(Assembler::is_polling_page_far(), "unexpected poll encoding");)
+    return true;
+  }
+  return false;
 #else
   return ( ubyte_at(0) == NativeMovRegMem::instruction_code_mem2reg ||
            ubyte_at(0) == NativeTstRegMem::instruction_code_memXregl ) &&