textmate stdin I7jXA3.txt

diff --git a/vm/string.c b/vm/string.c
index 64fa97e..9e8dd3e 100644
--- a/vm/string.c
+++ b/vm/string.c
@@ -1,3 +1,4 @@
+#include <alloca.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include "tr.h"
@@ -124,14 +125,11 @@ OBJ tr_sprintf(VM, const char *fmt, ...) {
   va_list arg;
   va_start(arg, fmt);
   int len = vsnprintf(NULL, 0, fmt, arg);
-  /* HACK causes Bus error in Bohem GC */
-  /* char *ptr = TR_ALLOC_N(char, len); */
-  char ptr[4096]; assert(len < 4096);
+  char *ptr = alloca(sizeof(char) * len);
   va_end(arg);
   va_start(arg, fmt);
   vsprintf(ptr, fmt, arg);
   va_end(arg);
-  /* TODO do not allocate twice */
   OBJ str = TrString_new(vm, ptr, len);
   TR_FREE(ptr);
   return str;
diff --git a/vm/vm.c b/vm/vm.c
index 79cfcc0..1c76488 100644
--- a/vm/vm.c
+++ b/vm/vm.c
@@ -129,15 +129,16 @@ static inline OBJ TrVM_yield(VM, TrFrame *f, int argc, OBJ argv[]) {
 #define SITE   (b->sites.a)
 
 static OBJ TrVM_interpret(VM, register TrFrame *f, TrBlock *b, int start, int argc, OBJ argv[], TrClosure *closure) {
+  OBJ *stacka = alloca(sizeof(OBJ) * b->regc);
 #if TR_USE_MACHINE_REGS && __i386__
   register TrInst *ip __asm__ ("esi") = b->code.a + start;
-  register OBJ *stack __asm__ ("edi") = f->stack;
+  register OBJ *stack __asm__ ("edi") = stacka;
 #elif TR_USE_MACHINE_REGS && __x86_64__
   register TrInst *ip __asm__ ("r15") = b->code.a + start;
-  register OBJ *stack __asm__ ("r14") = f->stack;
+  register OBJ *stack __asm__ ("r14") = stacka;
 #else
   register TrInst *ip = b->code.a + start;
-  register OBJ *stack = f->stack;
+  register OBJ *stack = stacka;
 #endif
   TrInst i = *ip;
   OBJ *k = b->k.a;