Python: Prevent bad magic during pruning.

taus-semmle · taus-semmle · commit a58c16f91c71 · 2019-08-20T16:18:42.000+02:00
Fixes the performance regression seen on `uncompyle2` and similar projects.
diff --git a/python/ql/src/semmle/python/Pruning.qll b/python/ql/src/semmle/python/Pruning.qll
@@ -525,6 +525,7 @@ module Pruner {
     }
 
     /** Holds if `cond` holds for `var` on conditional edge `pred` -> `succ` as a result of the test for that edge */
+    pragma [nomagic]
     predicate constraintOnBranch(UnprunedBasicBlock pred, UnprunedBasicBlock succ, Constraint cond, SsaVariable var) {
         cond = constraintFromTest(var, pred.last()) and
         succ = pred.getATrueSuccessor()

Original file line number	Diff line number	Diff line change
`@@ -525,6 +525,7 @@ module Pruner {`
`525`	`525`	`}`
`526`	`526`
`527`	`527`	/** Holds if `cond` holds for `var` on conditional edge `pred` -> `succ` as a result of the test for that edge */
	`528`	`+ pragma [nomagic]`
`528`	`529`	`predicate constraintOnBranch(UnprunedBasicBlock pred, UnprunedBasicBlock succ, Constraint cond, SsaVariable var) {`
`529`	`530`	`cond = constraintFromTest(var, pred.last()) and`
`530`	`531`	`succ = pred.getATrueSuccessor()`