simplify primitive code

jumpforth.S

@@ -1145,8 +1145,7 @@ defcode FROMR,"R>"
 
 /* ( R: a -- a ) ( -- a ) */
 defcode RFETCH,"R@"
-   movl (%ebp),%eax
-   push %eax
+   pushl (%ebp)
    NEXT
 
 /* ( R: xu ... x0 -- xu ... x0 ) ( S: u -- xu ) */
@@ -1173,10 +1172,8 @@ defcode TWOFROMR,"2R>"
 
 /* ( R: a b -- a b ) ( -- a b ) */
 defcode TWORFETCH,"2R@"
-   movl (%ebp),%ebx
-   movl 4(%ebp),%eax
-   push %eax
-   push %ebx
+   pushl 4(%ebp)
+   pushl (%ebp)
    NEXT
 
 /* ( xu ... x1 u -- ) ( R: -- xu ... x1 u ) */
@@ -1296,15 +1293,15 @@ defcode EXECUTE
 
 /* ( ebx ecx edx esi edi ebp eax/sc -- eax/result ) */
 defcode SYSCALL6
+   mov %ebp,%ecx
+   mov %esi,%ebx
    pop %eax
-   movl 16(%esp),%ecx
-   movl %ebp,16(%esp)
    pop %ebp
    pop %edi
-   movl 12(%esp),%ebx
-   movl %esi,12(%esp)
    pop %esi
    pop %edx
+   xchg %ecx,(%esp)
+   xchg %ebx,4(%esp)
    int $0x80
    pop %ebp
    pop %esi
@@ -1313,13 +1310,13 @@ defcode SYSCALL6
 
 /* ( ebx ecx edx esi edi eax/sc -- eax/result ) */
 defcode SYSCALL5
+   mov %esi,%ebx
    pop %eax
    pop %edi
-   movl 12(%esp),%ebx
-   movl %esi,12(%esp)
    pop %esi
    pop %edx
    pop %ecx
+   xchg %ebx,(%esp)
    int $0x80
    pop %esi
    push %eax
@@ -1327,14 +1324,14 @@ defcode SYSCALL5
 
 /* ( ebx ecx edx esi eax/sc -- eax/result ) */
 defcode SYSCALL4
+   mov %esi,%edi
    pop %eax
-   movl 12(%esp),%ebx
-   movl %esi,12(%esp)
    pop %esi
    pop %edx
    pop %ecx
+   pop %ebx
    int $0x80
-   pop %esi
+   mov %edi,%esi
    push %eax
    NEXT