[PATCH] D96208: [AssumptionCache] Do not track llvm.assume calls (PR49043)

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert created this revision.
jdoerfert added reviewers: jonpa, lebedev.ri, nikic.
Herald added a reviewer: bollu.
jdoerfert requested review of this revision.
Herald added a project: LLVM.

This fixes PR49043 by invalidating the handle on RAUW. This will work
fine assuming all existing RAUW users add the new assumption to the
cache. That means, if a new llvm.assume call replaces an old one, you
need to add the new one now as a RAUW is not enough anymore.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D96208

Files:
  llvm/include/llvm/Analysis/AssumptionCache.h
  llvm/test/Transforms/GVNSink/assumption.ll


Index: llvm/test/Transforms/GVNSink/assumption.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/GVNSink/assumption.ll
@@ -0,0 +1,32 @@
+; RUN: opt < %s -S -passes="print<assumptions>,gvn-sink,loop-unroll" -unroll-count=3 | FileCheck %s
+;
+; This crashed because the cached assumption was replaced and the replacement
+; was then in the cache twice.
+;
+; PR49043
+
+ at g = external global i32
+
+define void @main() {
+bb:
+  %i1.i = load volatile i32, i32* @g
+  %i32.i = icmp eq i32 %i1.i, 0
+  call void @llvm.assume(i1 %i32.i) #3
+  br label %bb4.i
+
+bb4.i:                                            ; preds = %bb4.i, %bb
+  %i.i = load volatile i32, i32* @g
+  %i3.i = icmp eq i32 %i.i, 0
+  call void @llvm.assume(i1 %i3.i) #3
+  br label %bb4.i
+
+func_1.exit:                                      ; No predecessors!
+  unreachable
+}
+
+declare void @llvm.assume(i1)
+
+; CHECK:  call void @llvm.assume(
+; CHECK:  call void @llvm.assume(
+; CHECK:  call void @llvm.assume(
+
Index: llvm/include/llvm/Analysis/AssumptionCache.h
===================================================================
--- llvm/include/llvm/Analysis/AssumptionCache.h
+++ llvm/include/llvm/Analysis/AssumptionCache.h
@@ -45,7 +45,7 @@
   enum : unsigned { ExprResultIdx = std::numeric_limits<unsigned>::max() };
 
   struct ResultElem {
-    WeakTrackingVH Assume;
+    WeakVH Assume;
 
     /// contains either ExprResultIdx or the index of the operand bundle
     /// containing the knowledge.


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