fix OS X PowerPC parameter passing

We were not always placing parameters in the correct stack positions
in the PowerPC implementations of dynamicCall and vmNativeCall.  In
particular, the first stack slot used to hold a parameter depends on
the sizes and types of the preceding parameters which are passed in
registers.

src/powerpc.S

@@ -36,13 +36,14 @@ GLOBAL(vmNativeCall):
    mflr r0
    stw  r0,RETURN_ADDRESS_OFFSET(r1)
    
-   // r3 aka r13: function
-   // r4        : stackTotal
-   // r5        : memoryTable
-   // r6        : memoryCount
-   // r7        : gprTable
-   // r8        : fprTable
-   // r9 aka r14: returnType
+   // r3  aka r13: function
+   // r4         : stackTotal
+   // r5         : memoryTable
+   // r6         : memoryCount
+   // r7         : memoryBase
+   // r8         : gprTable
+   // r9         : fprTable
+   // r10 aka r14: returnType
    
    // r15       : stack frame size
    // r16       : temporary
@@ -51,34 +52,34 @@ GLOBAL(vmNativeCall):
 
    // allocate stack space, adding room for callee-saved registers and
    // scratch space for copying a FP return value into GPRs
-   subfic r10,r4,-48
-	 stwux r1,r1,r10
+   subfic r11,r4,-48
+	 stwux r1,r1,r11
 
    // save callee-saved registers used for local variables
-   add  r10,r4,r1
+   add  r11,r4,r1
 
    // save registers used for local variables
-   stw  r13,0(r10)
-   stw  r14,4(r10)
-   stw  r15,8(r10)
-   stw  r16,12(r10)
-   stw  r17,16(r10)
-   stw  r18,20(r10)
-   stw  r19,24(r10)
+   stw  r13,0(r11)
+   stw  r14,4(r11)
+   stw  r15,8(r11)
+   stw  r16,12(r11)
+   stw  r17,16(r11)
+   stw  r18,20(r11)
+   stw  r19,24(r11)
 
    // remember where we saved the local variables
-   mr   r19,r10
+   mr   r19,r11
 
    // save our argument registers so we can clobber them
    mr   r13,r3
-   mr   r14,r9
+   mr   r14,r10
 
    li   r16,0
    b    LOCAL(test)
    
 LOCAL(loop):
    lwzx r17,r16,r5
-   addi r18,r16,MEMORY_BASE
+   add  r18,r16,r7
    stwx r17,r18,r1
    addi r16,r16,BYTES_PER_WORD
    
@@ -87,33 +88,33 @@ LOCAL(test):
    blt  LOCAL(loop)
 
    // do we need to load the floating point registers?
-   cmpwi r8,0
+   cmpwi r9,0
    beq   LOCAL(gpr)
 
    // yes, we do
-   lfd  f1,0(r8)
-   lfd  f2,8(r8)
-   lfd  f3,16(r8)
-   lfd  f4,24(r8)
-   lfd  f5,32(r8)
-   lfd  f6,40(r8)
-   lfd  f7,48(r8)
-   lfd  f8,56(r8)
+   lfd  f1,0(r9)
+   lfd  f2,8(r9)
+   lfd  f3,16(r9)
+   lfd  f4,24(r9)
+   lfd  f5,32(r9)
+   lfd  f6,40(r9)
+   lfd  f7,48(r9)
+   lfd  f8,56(r9)
 #ifdef __APPLE__
-   lfd  f9,64(r8)
-   lfd  f10,72(r8)
-   lfd  f11,80(r8)
-   lfd  f12,88(r8)
-   lfd  f13,96(r8)
+   lfd  f9,64(r9)
+   lfd  f10,72(r9)
+   lfd  f11,80(r9)
+   lfd  f12,88(r9)
+   lfd  f13,96(r9)
 #endif
 
 LOCAL(gpr):
    // do we need to load the general-purpose registers?
-   cmpwi r7,0
+   cmpwi r8,0
    beq  LOCAL(call)
 
    // yes, we do
-   mr   r16,r7
+   mr   r16,r8
    lwz  r3,0(r16)
    lwz  r4,4(r16)
    lwz  r5,8(r16)

src/powerpc.h

@@ -57,8 +57,8 @@
 
 extern "C" uint64_t
 vmNativeCall(void* function, unsigned stackTotal, void* memoryTable,
-             unsigned memoryCount, void* gprTable, void* fprTable,
-             unsigned returnType);
+             unsigned memoryCount, unsigned memoryBase,
+             void* gprTable, void* fprTable, unsigned returnType);
 
 namespace vm {
 
@@ -239,6 +239,7 @@ dynamicCall(void* function, uintptr_t* arguments, uint8_t* argumentTypes,
     (function,
      (((1 + stackSkip + stackIndex) * BytesPerWord) + LinkageArea + 15) & -16,
      stack, stackIndex * BytesPerWord,
+     LinkageArea + (stackSkip * BytesPerWord),
      (gprIndex ? gprTable : 0),
      (fprIndex ? fprTable : 0), returnType);
 }