[PATCH] D134531: [SCEV] Verify block disposition cache.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: lebedev.ri, nikic, reames, mkazantsev.
Herald added subscribers: javed.absar, hiraditya.
Herald added a project: All.
fhahn requested review of this revision.
Herald added a project: LLVM.

This extends the existing SCEV verification to catch cache invalidation
issues as in #57837.

The validation logic is similar to the recently added loop disposition
cache validation in bb68b2402daa9 <https://reviews.llvm.org/rGbb68b2402daa980ff41406a7ecf5e9f4e131b420>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D134531

Files:
  llvm/lib/Analysis/ScalarEvolution.cpp
  llvm/test/Transforms/LoopDeletion/pr57837-invalidate-scev-after-hoisting.ll


Index: llvm/test/Transforms/LoopDeletion/pr57837-invalidate-scev-after-hoisting.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/LoopDeletion/pr57837-invalidate-scev-after-hoisting.ll
@@ -0,0 +1,45 @@
+; RUN: opt -passes='loop(indvars,loop-deletion),verify<scalar-evolution>' -S %s
+
+; XFAIL: *
+; FIXME: Currently fails verification.
+
+; Make sure the SCEV for %invar is invalidated properly when the instruction is
+; moved by LoopDeletion.
+
+define void @test() {
+bb:
+  br label %outer.header
+
+outer.header:                                              ; preds = %bb19, %bb
+  %outer.iv = phi i32 [ 0, %bb ], [ %tmp21, %outer.latch ]
+  %outer.cmp = icmp ult i32 %outer.iv, 400
+  br i1 %outer.cmp, label %inner.ph, label %outer.latch
+
+inner.ph:
+  br label %inner
+
+inner:
+  %p = phi i32 [ poison, %inner.ph ], [ %invar, %inner ]
+  %inner.iv = phi i32 [ 1, %inner.ph ], [ %inner.iv.next , %inner ]
+  %add.1 = add i32 %p, 30586
+  call void @use(i32 %add.1)
+  %invar = ashr i32 0, 3
+  %inner.iv.next = add nuw nsw i32 %inner.iv, 1
+  %invar.add = add i32 %invar, 407
+  %inner.cmp = icmp slt i32 %inner.iv.next, %invar.add
+  br i1 %inner.cmp, label %inner, label %inner.exit
+
+inner.exit:
+  br label %outer.latch
+
+outer.latch:
+  %merge = phi i32 [ 0, %outer.header ], [ %invar, %inner.exit ]
+  call void @use(i32 %merge)
+  %tmp21 = add i32 %outer.iv, 1
+  br i1 true, label %exit, label %outer.header
+
+exit:
+  ret void
+}
+
+declare void @use(i32)
Index: llvm/lib/Analysis/ScalarEvolution.cpp
===================================================================
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -13989,6 +13989,22 @@
       }
     }
   }
+
+  // Verify integrity of the block disposition cache.
+  for (const auto &It : BlockDispositions) {
+    const SCEV *S = It.first;
+    auto &Values = It.second;
+    for (auto &V : Values) {
+      auto CachedDisposition = V.getInt();
+      const BasicBlock *BB = V.getPointer();
+      const auto RecomputedDisposition = SE2.getBlockDisposition(S, BB);
+      if (CachedDisposition != RecomputedDisposition) {
+        dbgs() << "Cached disposition of " << *S << " for block %"
+               << BB->getName() << " is incorrect! \n";
+        std::abort();
+      }
+    }
+  }
 }
 
 bool ScalarEvolution::invalidate(


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