unsign in zext to prevent a sign error

2 files changed, 23 insertions, 10 deletions

diff --git a/src/jsifier.js b/src/jsifier.js
index 9a405f55..edf8c6fa 100644
--- a/src/jsifier.js
+++ b/src/jsifier.js
@@ -753,6 +753,8 @@ function JSify(data, functionsOnly, givenTypes, givenFunctions, givenGlobalVaria
   });
 
   function makeSignOp(value, type, op) {
+    if (!value) return value;
+    if (!GUARD_SIGNS) return value;
     if (type in Runtime.INT_TYPES) {
       var bits = parseInt(type.substr(1));
       return op + 'Sign(' + value + ', ' + bits + ')';
@@ -772,16 +774,16 @@ function JSify(data, functionsOnly, givenTypes, givenFunctions, givenGlobalVaria
     for (var i = 1; i <= 4; i++) {
       if (item['param'+i]) {
         item['ident'+i] = indexizeFunctions(finalizeLLVMParameter(item['param'+i]));
+      } else {
+        item['ident'+i] = null; // just so it exists for purposes of reading ident2 etc. later on, and no exception is thrown
       }
     }
-    if (GUARD_SIGNS) {
-      if (op[0] == 'u' || (variant && variant[0] == 'u')) {
-        ident1 = makeSignOp(ident1, type, 'un');
-        ident2 = makeSignOp(ident2, type, 'un');
-      } else if (op[0] == 's' || (variant && variant[0] == 's')) {
-        ident1 = makeSignOp(ident1, type, 're');
-        ident2 = makeSignOp(ident2, type, 're');
-      }
+    if (op[0] == 'u' || op[0] == 'z' || (variant && variant[0] == 'u')) { // z for zext, see below
+      ident1 = makeSignOp(ident1, type, 'un');
+      ident2 = makeSignOp(ident2, type, 'un');
+    } else if (op[0] == 's' || (variant && variant[0] == 's')) {
+      ident1 = makeSignOp(ident1, type, 're');
+      ident2 = makeSignOp(ident2, type, 're');
     }
     var bits = null;
     if (item.type[0] === 'i') {
@@ -838,13 +840,17 @@ function JSify(data, functionsOnly, givenTypes, givenFunctions, givenGlobalVaria
           default: throw 'Unknown fcmp variant: ' + variant;
         }
       }
-      case 'zext': case 'fpext': case 'sext': case 'fptrunc': return ident1;
+      // Note that zext has sign checking, see above. We must guard against -33 in i8 turning into -33 in i32
+      // then unsigning that i32... which would give something huge.
+      case 'zext': case 'fpext': case 'sext': return ident1;
+      case 'fptrunc': return ident1;
       case 'trunc': {
         // Unlike extending, which we just 'do' (by doing nothing),
         // truncating can change the number, e.g. by truncating to an i1
         // in order to get the first bit
         assert(ident2[0] == 'i');
         var bitsLeft = ident2.substr(1);
+        assert(bitsLeft <= 32, 'Cannot truncate to more than 32 bits, since we use a native & op');
         return '((' + ident1 + ') & ' + (Math.pow(2, bitsLeft)-1) + ')';
       }
       case 'select': return ident1 + ' ? ' + ident2 + ' : ' + ident3;
diff --git a/src/library.js b/src/library.js
index b60bd07f..4b315a9e 100644
--- a/src/library.js
+++ b/src/library.js
@@ -168,6 +168,12 @@ var Library = {
       }
     }
     return Pointer_make(ret.concat(0), 0, ALLOC_STACK); // NB: Stored on the stack
+    //var len = ret.length+1;
+    //var ret = Pointer_make(ret.concat(0), 0, ALLOC_STACK); // NB: Stored on the stack
+    //STACKTOP -= len; // XXX horrible hack. we rewind the stack, to 'undo' the alloc we just did.
+    //                 // the point is that this works if nothing else allocs on the stack before
+    //                 // the string is read, which should be true - it is very transient, see the *printf* functions below.
+    //return ret;
   },
 
   printf__deps: ['_formatString'],
@@ -451,7 +457,7 @@ var Library = {
   exit: function(status) {
     __shutdownRuntime__();
     ABORT = true;
-    throw 'exit(' + status + ') called.';
+    throw 'exit(' + status + ') called, at ' + new Error().stack;
   },
 
   atexit: function(func) {
@@ -541,6 +547,7 @@ var Library = {
       // TODO: optimize for the typed arrays case
       // || 0, since memcpy sometimes copies uninitialized areas XXX: Investigate why initializing alloc'ed memory does not fix that too
       {{{ makeCopyValue('dest', 'i', 'src', 'i', 'null', ' || 0') }}};
+      // XXX Try copying the safe-heap type info, instead of using null
     }
   },
   llvm_memcpy_i32: 'memcpy',