From 3991b47946784354686aa3275a88458a4ca3d6af Mon Sep 17 00:00:00 2001
From: Philip Reames <listmail@philipreames.com>
Date: Mon, 13 Apr 2015 17:35:55 +0000
Subject: [PATCH] [RewriteStatepointsForGC] Strengthen assertions around
liveness
This is related to the issues addressed in 234651. These assertions check the properties ensured by that change at the place of use. Note that a similiar property is checked in checkBasicSSA, but without the reachability constraint. Technically, the liveness would be correct to include unreachable values, but this would be problematic for actual relocation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234766 91177308-0d34-0410-b5e6-96231b3b80d8
---
.../Scalar/RewriteStatepointsForGC.cpp | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
index 1f2597c7426..b4752243b6a 100644
--- a/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -1879,6 +1879,24 @@ static bool insertParsePoints(Function &F, DominatorTree &DT, Pass *P,
Statepoint statepoint(info.StatepointToken);
live.insert(live.end(), statepoint.gc_args_begin(),
statepoint.gc_args_end());
+#ifndef NDEBUG
+ // Do some basic sanity checks on our liveness results before performing
+ // relocation. Relocation can and will turn mistakes in liveness results
+ // into non-sensical code which is must harder to debug.
+ // TODO: It would be nice to test consistency as well
+ assert(DT.isReachableFromEntry(info.StatepointToken->getParent()) &&
+ "statepoint must be reachable or liveness is meaningless");
+ for (Value *V : statepoint.gc_args()) {
+ if (!isa<Instruction>(V))
+ // Non-instruction values trivial dominate all possible uses
+ continue;
+ auto LiveInst = cast<Instruction>(V);
+ assert(DT.isReachableFromEntry(LiveInst->getParent()) &&
+ "unreachable values should never be live");
+ assert(DT.dominates(LiveInst, info.StatepointToken) &&
+ "basic SSA liveness expectation violated by liveness analysis");
+ }
+#endif
}
unique_unsorted(live);
--
2.40.0