re-enable support for non-fixed i64 bitshifts

3 files changed, 77 insertions, 13 deletions

diff --git a/src/parseTools.js b/src/parseTools.js
index a53ff1c0..815d1a1b 100644
--- a/src/parseTools.js
+++ b/src/parseTools.js
@@ -1616,7 +1616,9 @@ function processMathop(item) {
       case 'shl':
       case 'ashr':
       case 'lshr': {
-        assert(isNumber(ident2));
+        if (!isNumber(ident2)) {
+          return 'Runtime.bitshift64(' + ident1 + ',"' + op + '",' + stripCorrections(ident2) + '[0]|0)';
+        }
         bits = parseInt(ident2);
         var ander = Math.pow(2, bits)-1;
         if (bits < 32) {
@@ -1892,17 +1894,28 @@ function finalizeBlockAddress(param) {
 
 function stripCorrections(param) {
   var m;
-  if (m = /^\((.*)\)$/.exec(param)) {
-    param = m[1];
-  }
-  if (m = /^\((\w+)\)&\d+$/.exec(param)) {
-    param = m[1];
-  }
-  if (m = /^\((\w+)\)\|0$/.exec(param)) {
-    param = m[1];
-  }
-  if (m = /CHECK_OVERFLOW\(([^,)]*),.*/.exec(param)) {
-    param = m[1];
+  while (true) {
+    if (m = /^\((.*)\)$/.exec(param)) {
+      param = m[1];
+      continue;
+    }
+    if (m = /^\(([$_\w]+)\)&\d+$/.exec(param)) {
+      param = m[1];
+      continue;
+    }
+    if (m = /^\(([$_\w()]+)\)\|0$/.exec(param)) {
+      param = m[1];
+      continue;
+    }
+    if (m = /^\(([$_\w()]+)\)\>>>0$/.exec(param)) {
+      param = m[1];
+      continue;
+    }
+    if (m = /CHECK_OVERFLOW\(([^,)]*),.*/.exec(param)) {
+      param = m[1];
+      continue;
+    }
+    break;
   }
   return param;
 }
diff --git a/src/runtime.js b/src/runtime.js
index 8e5238da..39aed12c 100644
--- a/src/runtime.js
+++ b/src/runtime.js
@@ -118,6 +118,41 @@ var Runtime = {
   INT_TYPES: set('i1', 'i8', 'i16', 'i32', 'i64'),
   FLOAT_TYPES: set('float', 'double'),
 
+  // Mirrors processMathop's treatment of constants (which we optimize directly)
+  bitshift64: function(value, op, bits) {
+    var ander = Math.pow(2, bits)-1;
+    if (bits < 32) {
+      switch (op) {
+        case 'shl':
+          return [value[0] << bits, (value[1] << bits) | ((value[0]&(ander << (32 - bits))) >>> (32 - bits))];
+        case 'ashr':
+          return [(((value[0] >>> bits ) | ((value[1]&ander) << (32 - bits))) >> 0) >>> 0, (value[1] >> bits) >>> 0];
+        case 'lshr':
+          return [((value[0] >>> bits) | ((value[1]&ander) << (32 - bits))) >>> 0, value[1] >>> bits];
+      }
+    } else if (bits == 32) {
+      switch (op) {
+        case 'shl':
+          return [0, value[0]];
+        case 'ashr':
+          return [value[1], (value[1]|0) < 0 ? ander : 0];
+        case 'lshr':
+          return [value[1], 0];
+      }
+    } else { // bits > 32
+      switch (op) {
+        case 'shl':
+          return [0, value[0] << (bits - 32)];
+        case 'ashr':
+          return [(value[1] >> (bits - 32)) >>> 0, (value[1]|0) < 0 ? ander : 0];
+        case 'lshr':
+          return [value[1] >>>  (bits - 32) , 0];
+      }
+    }
+    abort('unknown bitshift64 op: ' + [value, op, bits]);
+  },
+
+  // Imprecise bitops utilities
   or64: function(x, y) {
     var l = (x | 0) | (y | 0);
     var h = (Math.round(x / 4294967296) | Math.round(y / 4294967296)) * 4294967296;
diff --git a/tests/runner.py b/tests/runner.py
index 2a0307e9..55d0bd0b 100755
--- a/tests/runner.py
+++ b/tests/runner.py
@@ -496,7 +496,7 @@ if 'benchmark' not in str(sys.argv) and 'sanity' not in str(sys.argv):
              { 122, 25769803837 },
           };
 
-          int main()
+          int main(int argc, char **argv)
           {
             int64_t x1 = 0x1234def123450789ULL;
             int64_t x2 = 0x1234def123450788ULL;
@@ -533,6 +533,20 @@ if 'benchmark' not in str(sys.argv) and 'sanity' not in str(sys.argv):
               printf("*%Ld,%Ld,%Ld,%Ld*\n", ua, ub, uc, ud);
             }
 
+            // Nonconstant bitshifts
+            {
+              int64_t a = -1;
+              int64_t b = a >> (29 - argc + 1);
+              int64_t c = a >> (32 - argc + 1);
+              int64_t d = a >> (34 - argc + 1);
+              printf("*%Ld,%Ld,%Ld,%Ld*\n", a, b, c, d);
+              uint64_t ua = -1;
+              int64_t ub = ua >> (29 - argc + 1);
+              int64_t uc = ua >> (32 - argc + 1);
+              int64_t ud = ua >> (34 - argc + 1);
+              printf("*%Ld,%Ld,%Ld,%Ld*\n", ua, ub, uc, ud);
+            }
+
             // Math mixtures with doubles
             {
               uint64_t a = 5;
@@ -565,6 +579,8 @@ if 'benchmark' not in str(sys.argv) and 'sanity' not in str(sys.argv):
                          '*122,25769803837*\n' +
                          '*-1,-1,-1,-1*\n' +
                          '*-1,34359738367,4294967295,1073741823*\n' +
+                         '*-1,-1,-1,-1*\n' +
+                         '*-1,34359738367,4294967295,1073741823*\n' +
                          '*prod:34*')
 
         Settings.CORRECT_SIGNS = 1