VM: fix jit-signal-handler-prolog/epilog to account for the home space

Windows 64bit abi requires callers to reserve 32 bytes of home space in
the stack frame which the callee is free to clobber. Previous versions
of VS didn't compile code to take advantage of the home space so it
worked fined. VS2015 however, is using the home space which causes
registers and flags that were supposed to be saved to be
overwritten. The fix is to put a little extra empty space at the bottom
of the stack frame.

basis/bootstrap/assembler/x86.32.factor

@@ -8,7 +8,6 @@ IN: bootstrap.x86
 
 4 \ cell set
 
-: signal-handler-stack-frame-size ( -- n ) 12 bootstrap-cells ;
 : stack-frame-size ( -- n ) 8 bootstrap-cells ;
 : shift-arg ( -- reg ) ECX ;
 : div-arg ( -- reg ) EAX ;

basis/bootstrap/assembler/x86.64.unix.factor

@@ -4,7 +4,6 @@ USING: cpu.x86.assembler.operands kernel layouts parser
 sequences ;
 IN: bootstrap.x86
 
-: signal-handler-stack-frame-size ( -- n ) 20 bootstrap-cells ;
 : stack-frame-size ( -- n ) 4 bootstrap-cells ;
 : nv-regs ( -- seq ) { RBX R12 R13 R14 R15 } ;
 : volatile-regs ( -- seq ) { RAX RCX RDX RSI RDI R8 R9 R10 R11 } ;

basis/bootstrap/assembler/x86.64.windows.factor

@@ -6,7 +6,6 @@ IN: bootstrap.x86
 
 DEFER: stack-reg
 
-: signal-handler-stack-frame-size ( -- n ) 24 bootstrap-cells ;
 : stack-frame-size ( -- n ) 8 bootstrap-cells ;
 : nv-regs ( -- seq ) { RBX RSI RDI R12 R13 R14 R15 } ;
 : volatile-regs ( -- seq ) { RAX RCX RDX R8 R9 R10 R11 } ;

basis/bootstrap/assembler/x86.factor

@@ -92,28 +92,30 @@ big-endian off
 ! The *-signal-handler subprimitives are special-cased in vm/quotations.cpp
 ! not to trigger generation of a stack frame, so they can
 ! peform their own prolog/epilog preserving registers.
-
+!
+! It is important that the total is 192/64 and that it matches the
+! constants in vm/cpu-x86.*.hpp
 : jit-signal-handler-prolog ( -- )
-    ! minus a cell each for flags, return address
+    ! Return address already on stack -> 8/4 bytes.
-    ! use LEA so we don't dirty flags
-    stack-reg stack-reg signal-handler-stack-frame-size
-    2 bootstrap-cells - neg [+] LEA
 
-    signal-handler-save-regs
+    ! Push all registers. 15 regs/120 bytes on 64bit, 7 regs/28 bytes
-    [| r i | stack-reg i bootstrap-cells [+] r MOV ] each-index
+    ! on 32bit -> 128/32 bytes.
+    signal-handler-save-regs [ PUSH ] each
 
+    ! Push flags -> 136/36 bytes
     PUSHF
 
+    ! Register parameter area 32 bytes, unused on platforms other than
+    ! windows 64 bit, but including it doesn't hurt. Plus
+    ! alignment. LEA used so we don't dirty flags -> 192/64 bytes.
+    stack-reg stack-reg 7 bootstrap-cells neg [+] LEA
+
     jit-load-vm ;
 
 : jit-signal-handler-epilog ( -- )
+    stack-reg stack-reg 7 bootstrap-cells [+] LEA
     POPF
-
+    signal-handler-save-regs reverse [ POP ] each ;
-    signal-handler-save-regs
-    [| r i | r stack-reg i bootstrap-cells [+] MOV ] each-index
-
-    stack-reg stack-reg signal-handler-stack-frame-size
-    2 bootstrap-cells - [+] LEA ;
 
 [| |
     jit-signal-handler-prolog

vm/cpu-x86.32.hpp

@@ -2,9 +2,9 @@ namespace factor {
 
 #define FACTOR_CPU_STRING "x86.32"
 
-/* Must match the signal-handler-stack-frame-size and stack-frame-size
+/* Must match the calculation in word jit-signal-handler-prolog in
-   constants in bootstrap/assembler/x86.32.factor */
+   basis/bootstrap/assembler/x86.factor */
-static const unsigned SIGNAL_HANDLER_STACK_FRAME_SIZE = 48;
+static const unsigned SIGNAL_HANDLER_STACK_FRAME_SIZE = 64;
 static const unsigned JIT_FRAME_SIZE = 32;
 
 }

vm/cpu-x86.64.hpp

@@ -2,4 +2,8 @@ namespace factor {
 
 #define FACTOR_CPU_STRING "x86.64"
 
+/* Must match the calculation in word jit-signal-handler-prolog in
+   basis/bootstrap/assembler/x86.factor */
+static const unsigned SIGNAL_HANDLER_STACK_FRAME_SIZE = 192;
+
 }

vm/os-linux-x86.64.hpp

@@ -25,9 +25,8 @@ inline static void uap_clear_fpu_status(void* uap) {
 #define FUNCTION_CODE_POINTER(ptr) ptr
 #define FUNCTION_TOC_POINTER(ptr) ptr
 
-/* Must match the signal-handler-stack-frame-size and stack-frame-size
+/* Must match the stack-frame-size constant in
-   constants in bootstrap/assembler/x86.64.unix.factor */
+   bootstrap/assembler/x86.64.unix.factor */
-static const unsigned SIGNAL_HANDLER_STACK_FRAME_SIZE = 160;
 static const unsigned JIT_FRAME_SIZE = 32;
 
 }

vm/os-macosx-x86.64.hpp

@@ -67,9 +67,8 @@ inline static void uap_clear_fpu_status(void* uap) {
   mach_clear_fpu_status(UAP_FS(uap));
 }
 
-/* Must match the signal-handler-stack-frame-size and stack-frame-size
+/* Must match the stack-frame-size constant in
-   constants in basis/bootstrap/assembler/x86.64.unix.factor */
+   basis/bootstrap/assembler/x86.64.unix.factor */
-static const unsigned SIGNAL_HANDLER_STACK_FRAME_SIZE = 160;
 static const unsigned JIT_FRAME_SIZE = 32;
 
 }

vm/os-windows.64.hpp

@@ -7,8 +7,7 @@ namespace factor {
 
 #define MXCSR(ctx) (ctx)->MxCsr
 
-/* Must match the signal-handler-stack-frame-size and stack-frame-size
+/* Must match the stack-frame-size constant in
-   constants in basis/bootstap/assembler/x86.64.windows.factor */
+   basis/bootstap/assembler/x86.64.windows.factor */
-static const unsigned SIGNAL_HANDLER_STACK_FRAME_SIZE = 192;
 static const unsigned JIT_FRAME_SIZE = 64;
 }