[AssumptionCache] Avoid dangling llvm.assume calls in the cache

PR49043 exposed a problem when it comes to RAUW llvm.assumes. While
D96106 would fix it for GVNSink, it seems a more general concern. To
avoid future problems this patch moves away from the vector of weak
reference model used in the assumption cache. Instead, we track the
llvm.assume calls with a callback handle which will remove itself from
the cache if the call is deleted.

Fixes PR49043.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D96168

1 files changed, 2 insertions, 6 deletions

diff --git a/llvm/lib/Analysis/CodeMetrics.cpp b/llvm/lib/Analysis/CodeMetrics.cpp
index 157811c..b0b46cb 100644
--- a/llvm/lib/Analysis/CodeMetrics.cpp
+++ b/llvm/lib/Analysis/CodeMetrics.cpp
@@ -73,9 +73,7 @@ void CodeMetrics::collectEphemeralValues(
   SmallVector<const Value *, 16> Worklist;
 
   for (auto &AssumeVH : AC->assumptions()) {
-    if (!AssumeVH)
-      continue;
-    Instruction *I = cast<Instruction>(AssumeVH);
+    Instruction *I = AssumeVH.getAssumeCI();
 
     // Filter out call sites outside of the loop so we don't do a function's
     // worth of work for each of its loops (and, in the common case, ephemeral
@@ -97,9 +95,7 @@ void CodeMetrics::collectEphemeralValues(
   SmallVector<const Value *, 16> Worklist;
 
   for (auto &AssumeVH : AC->assumptions()) {
-    if (!AssumeVH)
-      continue;
-    Instruction *I = cast<Instruction>(AssumeVH);
+    Instruction *I = AssumeVH.getAssumeCI();
     assert(I->getParent()->getParent() == F &&
            "Found assumption for the wrong function!");