duskos

commit f1317253f641fb146334bc42fe4a807a5a029a2b
parent 8456f08100e83a08ee951ce4a06e6b57ed0c6aac
Author: Virgil Dupras <hsoft@hardcoded.net>
Date:   Wed, 16 Nov 2022 09:59:48 -0500

cc/vm: fix ill-conceived optimisation

Constant folding for <<n, >>n and +n can only be done on straight constants, not
constant pointers! My previous logic had no sense.

Diffstat:
M
fs/app/uxn/vm.c
 | 
11
++---------
M
fs/cc/type.fs
 | 
2
+-
M
fs/cc/vm/commonhi.fs
 | 
8
+++-----
M
fs/tests/cc/cc.fs
 | 
1
+
M
fs/tests/cc/test.c
 | 
7
+++++++

5 files changed, 14 insertions(+), 15 deletions(-)
diff --git a/fs/app/uxn/vm.c b/fs/app/uxn/vm.c
@@ -25,9 +25,7 @@ unsigned char ram[$10000];
 // TODO: allow single line decl
 static Stack wst;
 static Stack rst;
-// TODO: under i386, having a global struct pointer doesn't work and corrupts
-// memory all around.
-// static Stack *s;
+static Stack *s;
 static Device dev[$10];
 static unsigned short pc; // Program Counter
 
@@ -37,12 +35,10 @@ static void error(int code) {
 }
 
 void push8(unsigned char val) {
-    Stack *s = &wst;
     if (s->ptr == $ff) { error(2); } else { s->dat[s->ptr++] = val; }
 }
 
 void push(unsigned short val) {
-    Stack *s = &wst;
     if (s->ptr >= $fe) { error(2); } else {
         s->dat[s->ptr] = val >> 8;
         s->dat[s->ptr+1] = val;
@@ -51,13 +47,11 @@ void push(unsigned short val) {
 }
 
 unsigned char pop8() {
-    Stack *s = &wst;
     if (!s->ptr) { error(0); } else { return s->dat[--s->ptr]; }
 }
 
 unsigned short pop16() {
     unsigned short val;
-    Stack *s = &wst;
     if (s->ptr <= 1) { error(0); } else {
         s->ptr -= 2;
         val = s->dat[s->ptr] << 8;
@@ -91,7 +85,6 @@ static void _err() { error(42); }
 static void LIT() { push8(peek8(pc++)); }
 static void INC() { push8(pop8()+1); }
 static void DUP() { unsigned char x = pop8(); push8(x); push8(x); }
-// TODO: this doesn't work under i386
 static void ADD() { push8(pop8() + pop8()); }
 static VMOP ops[$20] = {
     LIT, INC, _err, _err, _err, _err, DUP, _err,
@@ -111,5 +104,5 @@ void uxn_init() {
     pc = $100;
     wst.ptr = 0;
     rst.ptr = 0;
-    // s = &wst;
+    s = &wst;
 }
diff --git a/fs/cc/type.fs b/fs/cc/type.fs
@@ -88,7 +88,7 @@ struct[ CType
   : :funcptr?
     type dup ctype? if
       dup type*lvl 1 = swap ctype' :funcsig? and
-      else 0 then ;
+      else drop 0 then ;
   : :isarg? ( dnode -- f ) storage STORAGE_PS = ;
   : :isglobal? ( dnode -- f ) storage STORAGE_MEM = ;
 
diff --git a/fs/cc/vm/commonhi.fs b/fs/cc/vm/commonhi.fs
@@ -7,15 +7,13 @@
 : bothconst? vmop :foldable? vmop^ :foldable? and ;
 
 struct+[ VMOp
-  \ We use ":isconstlo?" below because it make sense to apply those operations
-  \ on pointer to constants (addresses).
   : :<<n over if
-    dup :isconstlo? if tuck arg swap lshift swap to arg else VMOp :<<n then
+    dup :isconst? if tuck arg swap lshift swap to arg else VMOp :<<n then
     else 2drop then ;
   : :>>n over if
-    dup :isconstlo? if tuck arg swap rshift swap to arg else VMOp :>>n then
+    dup :isconst? if tuck arg swap rshift swap to arg else VMOp :>>n then
     else 2drop then ;
-  : :+n over if dup :isconstlo? if to+ arg else VMOp :+n then else 2drop then ;
+  : :+n over if dup :isconst? if to+ arg else VMOp :+n then else 2drop then ;
 ]struct
 
 UNOPCNT wordtbl constops ( n -- n )
diff --git a/fs/tests/cc/cc.fs b/fs/tests/cc/cc.fs
@@ -80,6 +80,7 @@ structop3 42 #eq
 structop4 globdata 12 + #eq
 structop5 42 #eq
 structop6 54 #eq
+structop7 42 #eq
 opwidth1 42 #eq
 opwidth2 42 #eq
 opwidth3 $129 #eq
diff --git a/fs/tests/cc/test.c b/fs/tests/cc/test.c
@@ -346,6 +346,13 @@ int structop6() {
     return n;
 }
 
+MyStruct *globdataptr;
+short structop7() {
+    globdata.bar = 42;
+    globdataptr = &globdata;
+    return globdataptr->bar;
+}
+
 // we used to leak VM ops in condition blocks without {}
 void cond1() {
     int x = 42;