[analyzer] Improve performance of the SVal simplification mechanism.

When neither LHS nor RHS of a binary operator expression can be simplified,
return the original expression instead of re-evaluating the binary operator.

Such re-evaluation was causing recusrive re-simplification which caused
the algorithmic complexity to explode.

Differential Revision: https://reviews.llvm.org/D47155

llvm-svn: 333670

1 files changed, 30 insertions, 0 deletions

diff --git a/clang/test/Analysis/hangs.c b/clang/test/Analysis/hangs.c
new file mode 100644
index 00000000000..b109bcb52fd
--- /dev/null
+++ b/clang/test/Analysis/hangs.c
@@ -0,0 +1,30 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker core -verify %s
+
+// expected-no-diagnostics
+
+// Stuff that used to hang.
+
+int g();
+
+int f(int y) {
+  return y + g();
+}
+
+int produce_a_very_large_symbol(int x) {
+  return f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(
+             f(f(f(f(f(f(f(f(f(f(f(f(f(f(f(x))))))))))))))))))))))))))))))));
+}
+
+void produce_an_exponentially_exploding_symbol(int x, int y) {
+  x += y; y += x + g();
+  x += y; y += x + g();
+  x += y; y += x + g();
+  x += y; y += x + g();
+  x += y; y += x + g();
+  x += y; y += x + g();
+  x += y; y += x + g();
+  x += y; y += x + g();
+  x += y; y += x + g();
+  x += y; y += x + g();
+  x += y; y += x + g();
+}