Fixed issue with aliasing local variables

ISPC++ now produces valid code, or an appropriate error message, for all
of my test cases.

tests_ispcpp/Makefile

@@ -1,5 +1,5 @@
 CXX=g++
-CXXFLAGS=-std=c++11
+CXXFLAGS=-std=c++11 -O2
 
 ISPC=../ispc
 ISPCFLAGS=--target=sse4-x2 -O2 --arch=x86-64

tests_ispcpp/hello.cpp

@@ -1,7 +1,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 
-#include "hello.ispc.h"
+#include "hello.h"
 
 int main() {
     float A[100];

tests_ispcpp/varying.cpp

@@ -0,0 +1,27 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "varying.h"
+
+int main() {
+    float A[256];
+    double B[256];
+    double outA[256];
+    double outB[256];
+
+
+    for (int i=0; i<256; i++) {
+        A[i] = 1. / (i+1);
+        B[i] = 1. / (i+1);
+    }
+
+    ispc::square(256, (float*)&A, (double*)&outA);
+
+    ispc::square(256, (double*)&B, (double*)&outB);
+
+    for (int i=0; i<256; i++) {
+        printf("float: %.16f\tdouble: %.16f\n", outA[i], outB[i]);
+    }
+
+    return 0;
+}

tests_ispcpp/varying.ispc

@@ -0,0 +1,14 @@
+floating foo(const uniform int a, floating b) {
+    floating out = b;
+    for (int i = 1; i<a; i++) {
+        out *= b;
+    }
+
+    return out;
+}
+
+export void square(uniform int N, uniform floating b[], uniform double out[]) {
+    foreach (i = 0 ... N) {
+        out[i] = foo(2, b[i]);
+    }
+}