[Reassociate] Invalidate analysis passes after canonicalizeOperands

llvm/lib/Transforms/Scalar/Reassociate.cpp

@@ -241,8 +241,10 @@ void ReassociatePass::canonicalizeOperands(Instruction *I) {
   Value *RHS = I->getOperand(1);
   if (LHS == RHS || isa<Constant>(RHS))
     return;
-  if (isa<Constant>(LHS) || getRank(RHS) < getRank(LHS))
+  if (isa<Constant>(LHS) || getRank(RHS) < getRank(LHS)) {
     cast<BinaryOperator>(I)->swapOperands();
+    MadeChange = true;
+  }
 }
 
 static BinaryOperator *CreateAdd(Value *S1, Value *S2, const Twine &Name,

llvm/test/Transforms/Reassociate/canonicalize-made-change.ll

@@ -0,0 +1,32 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes="print<demanded-bits>,reassociate,bdce" -S < %s | FileCheck %s
+
+; We want to verify that demanded-bits analysis is invalidated when
+; reassociate is canonicalizing expressions (e.g. putting the constant on the
+; RHS of an OR).
+;
+; Printing demanded-bits will make sure a demanded-bits analysis is cached.
+; Then we run reassociate, followed by bdce. When not invalidating demanded-bits
+; while doing reassociation of the OR, we got this kind of error:
+;
+;   Running pass: BDCEPass on foo (4 instructions)
+;   While deleting: i1 %cmp1
+;   Use still stuck around after Def is destroyed:  %or = or i1 %cmp1, true
+;   UNREACHABLE executed at ../lib/IR/Value.cpp:102!
+;
+; Check that we get the expected result without failing on assert/unreachable.
+
+define i1 @foo(i1 %c) {
+; CHECK-LABEL: define i1 @foo(
+; CHECK-SAME: i1 [[C:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    [[OR:%.*]] = or i1 false, true
+; CHECK-NEXT:    [[AND:%.*]] = and i1 [[OR]], [[C]]
+; CHECK-NEXT:    ret i1 [[AND]]
+;
+entry:
+  %cmp = icmp ne i16 0, 1
+  %or = or i1 true, %cmp
+  %and = and i1 %c, %or
+  ret i1 %and
+}