fix: fabs() working on the wrong argument

2 files changed, 17 insertions, 1 deletions

diff --git a/lib/Core/Executor.cpp b/lib/Core/Executor.cpp
index 48252dbd..7fac4fa4 100644
--- a/lib/Core/Executor.cpp
+++ b/lib/Core/Executor.cpp
@@ -1420,7 +1420,7 @@ void Executor::executeCall(ExecutionState &state, KInstruction *ki, Function *f,
       break;
     case Intrinsic::fabs: {
       ref<ConstantExpr> arg =
-          toConstant(state, eval(ki, 0, state).value, "floating point");
+          toConstant(state, arguments[0], "floating point");
       if (!fpWidthToSemantics(arg->getWidth()))
         return terminateStateOnExecError(
             state, "Unsupported intrinsic llvm.fabs call");
diff --git a/test/regression/2020-01-14-fabs-compare.c b/test/regression/2020-01-14-fabs-compare.c
new file mode 100644
index 00000000..563a6609
--- /dev/null
+++ b/test/regression/2020-01-14-fabs-compare.c
@@ -0,0 +1,16 @@
+// RUN: %clang %s -emit-llvm %O0opt -g -c -o %t.bc
+// RUN: rm -rf %t.klee-out
+// RUN: %klee --exit-on-error --output-dir=%t.klee-out %t.bc
+
+#include <math.h>
+#include <assert.h>
+
+int main(void) {
+  long double a = 0.25;
+  long double b = -a;
+
+  long double b_abs = fabsl(b);
+
+  assert(a == b_abs);
+  return 0;
+}