Author: ion
Date: Sat Jul 23 12:08:36 2011
New Revision: 52807
URL: http://svn.reactos.org/svn/reactos?rev=52807&view=rev
Log:
[KERNEL32]: Optimize SwitchToFiber to simply use "ret" to jump between fibers,
instead of saving EIP and doing a JMP.
Bug #50: SwitchToFiber needs to check if FXSR is *NOT* present in order to skip
using ldmxcsr/stmxcsr. Previously, it would check if it's unsupported, and jump
past the instruction if it was (resulting in invalid opcode instructions on
older systems)
50 bugs. Penance has been paid.
Modified:
trunk/reactos/dll/win32/kernel32/client/i386/fiber.S
Modified: trunk/reactos/dll/win32/kernel32/client/i386/fiber.S
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/dll/win32/kernel32/client/i386/fiber.S?rev=52807&r1=52806&r2=52807&view=diff
==============================================================================
--- trunk/reactos/dll/win32/kernel32/client/i386/fiber.S [iso-8859-1] (original)
+++ trunk/reactos/dll/win32/kernel32/client/i386/fiber.S [iso-8859-1] Sat Jul
23 12:08:36 2011
@@ -26,20 +26,16 @@
mov [eax+FIBER_CONTEXT_EDI], edi
mov [eax+FIBER_CONTEXT_EBP], ebp
- /* Save the return address */
- mov ebx, [esp]
- mov [eax+FIBER_CONTEXT_EIP], ebx
-
/* Check if we're to save FPU State */
cmp dword ptr [eax+FIBER_CONTEXT_FLAGS], CONTEXT_FULL OR
CONTEXT_FLOATING_POINT
jnz NoFpuStateSave
/* Save the FPU State (Status and Control)*/
fstsw [eax+FIBER_CONTEXT_FLOAT_SAVE_STATUS_WORD]
- fstcw [eax+FIBER_CONTEXT_FLOAT_SAVE_CONTROL_WORD]
+ fnstcw [eax+FIBER_CONTEXT_FLOAT_SAVE_CONTROL_WORD]
/* Check if the CPU supports SIMD MXCSR State Save */
- cmp byte ptr ds:[PROCESSOR_FEATURE_FXSR], 0
+ cmp byte ptr ds:[PROCESSOR_FEATURE_FXSR], 1
jnz NoFpuStateSave
stmxcsr [eax+FIBER_CONTEXT_DR6]
@@ -103,7 +99,7 @@
ControlWordEqual:
/* Load the new one */
- cmp byte ptr ds:[PROCESSOR_FEATURE_FXSR], 0
+ cmp byte ptr ds:[PROCESSOR_FEATURE_FXSR], 1
jnz NoFpuStateRestore
ldmxcsr [ecx+FIBER_CONTEXT_DR6]
@@ -121,7 +117,8 @@
mov [edx+TEB_FLS_DATA], eax
/* Jump to new fiber */
- jmp dword ptr [ecx+FIBER_CONTEXT_EIP]
+ mov esp, [ecx+FIBER_CONTEXT_ESP]
+ ret 4
+END
-END
/* EOF */
