PR11360: Make @defined and -L play nice

The constant-folding is now enabled for s.listing_mode_vars, despite all
other optimizations being disabled.  This is needed so we can prune any
invalid branches that are gated by @defined.

* elaborate.cxx (semantic_pass): Leave the optimization decision to the
  optimization passes themselves.
  (semantic_pass_optimize1): Predicate most optimizations, but enable the
  constant-folding for listing_mode_vars too.
  (semantic_pass_optimize2): Predicate all (1) optimizations.
* testsuite/semok/defined_list_vars.stp: New test.

1 files changed, 18 insertions, 0 deletions

diff --git a/testsuite/semok/defined_list_vars.stp b/testsuite/semok/defined_list_vars.stp
new file mode 100755
index 00000000..7f73ff05
--- /dev/null
+++ b/testsuite/semok/defined_list_vars.stp
@@ -0,0 +1,18 @@
+#! /bin/sh
+
+# PR11360 - Make sure that @defined and -L play well together.
+#
+# The test shouldn't be dependent on the implementation of syscall.poll, in
+# case that evolves, so I'm recreating the problematic condition here.
+#
+# NB: This is abusing the fact that -l/-L work by wrapping the input string
+# with "probe " and "{}"
+
+stap -L '
+my_syscall.poll = kernel.function("SyS_poll").call !,
+                  kernel.function("sys_poll").call
+{
+  timeout = (@defined($timeout_msecs) ? $timeout_msecs : $timeout)
+}
+probe my_syscall.poll
+' | grep " timeout:long"