Changeset 59527 in vbox for trunk/include/iprt/asm-watcom-x86-16.h

Timestamp:

Jan 31, 2016 11:54:20 AM (9 years ago)

Author:

vboxsync

Message:

iprt/asm.h: Experimented with alternative serializating instructions (ASMSerializeInstruction), cpuid(0) is very reasonable compared to iret (rdtscp would be preferable).

File:

• trunk/include/iprt/asm-watcom-x86-16.h (modified) (2 diffs)

trunk/include/iprt/asm-watcom-x86-16.h

@@ -150 +150 @@
 /* ASMAtomicCmpXchgExU64: External assembly implementation, too few registers for parameters.  */
 
-#undef      ASMSerializeInstruction
-#if 1
-# pragma aux ASMSerializeInstruction = \
+#undef      ASMSerializeInstructionCpuId
+#pragma aux ASMSerializeInstructionCpuId = \
+    ".586" \
+    "xor eax, eax" \
+    "cpuid" \
+    parm [] \
+    modify exact [ax bx cx dx];
+
+#undef ASMSerializeInstructionIRet
+#pragma aux ASMSerializeInstructionIRet = \
     "pushf" \
     "push cs" \
@@ -158 +165 @@
     "jmp  done" \
     "foo:" \
-    "iret" /* serializing */ \
+    "iret" \
     "done:" \
     parm [] \
-    modify exact [ax];
-#else
-# pragma aux ASMSerializeInstruction = \
-    ".586" \
-    "xor eax, eax" \
-    "cpuid" \
+    modify exact [];
+
+#undef      ASMSerializeInstructionRdTscp
+#pragma aux ASMSerializeInstructionRdTscp = \
+    0x0f 0x01 0xf9 \
     parm [] \
-    modify exact [ax bx cx dx];
-#endif
+    modify exact [ax dx cx];
 
 #undef      ASMAtomicReadU64