Added C test case that checks that concrete and symbolic overshift

behaviour for arithmetic right shift are identical.

1 files changed, 65 insertions, 0 deletions

diff --git a/test/Feature/arithmetic-right-overshift-sym-conc.c b/test/Feature/arithmetic-right-overshift-sym-conc.c
new file mode 100644
index 00000000..81995b2b
--- /dev/null
+++ b/test/Feature/arithmetic-right-overshift-sym-conc.c
@@ -0,0 +1,65 @@
+// RUN: %llvmgcc %s -emit-llvm -g -O0 -c -o %t.bc
+// RUN: %klee -use-cex-cache=1 -check-overshift=0 %t.bc
+// RUN: not grep "ASSERTION FAIL" %T/klee-last/messages.txt
+// RUN: grep "KLEE: done: explored paths = 1" %T/klee-last/info
+#include <stdio.h>
+#include <assert.h>
+
+typedef enum
+{
+    TO_ZERO,
+    MASKED,
+    UNKNOWN
+} overshift_t;
+
+// We're using signed ints so should be doing
+// arithmetic right shift.
+int overshift(volatile unsigned int y, const char * type)
+{
+    overshift_t ret;
+    volatile signed int x=15;
+    unsigned int limit = sizeof(x)*8;
+
+    volatile signed int result;
+    result = x >> y; // Potential overshift
+
+    if (result ==0)
+    {
+        printf("%s : Overshift to zero\n", type);
+        ret = TO_ZERO;
+    }
+    else if (result == ( x >> (y % limit)) )
+    {
+        printf("%s : Bitmasked overshift\n", type);
+        ret = MASKED;
+    }
+    else
+    {
+        printf("%s : Unrecognised behaviour.\n", type);
+        ret = UNKNOWN;
+    }
+
+    return ret;
+}
+
+int main(int argc, char** argv)
+{
+    // Concrete overshift
+    volatile unsigned int y = sizeof(unsigned int)*8;
+    overshift_t conc = overshift(y, "Concrete");
+    assert( conc == TO_ZERO);
+
+    // Symbolic overshift
+    volatile unsigned int y2;
+    klee_make_symbolic(&y2,sizeof(y),"y2");
+    // Add constraints so only one value possible
+    klee_assume(y2 > (y-1));
+    klee_assume(y2 < (y+1));
+    overshift_t sym = overshift(y2, "Symbolic");
+    assert( sym == TO_ZERO);
+
+    // Concrete and symbolic behaviour should be the same
+    assert( conc == sym);
+
+    return 0;
+}