[llvm] d9361bf - [VPlan] Add initial inner-loop VPlan verification.

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2021-11-09T10:18:28Z
New Revision: d9361bfbe2ce1f41c4e8ea2fb27b90d507c86838

URL: https://github.com/llvm/llvm-project/commit/d9361bfbe2ce1f41c4e8ea2fb27b90d507c86838
DIFF: https://github.com/llvm/llvm-project/commit/d9361bfbe2ce1f41c4e8ea2fb27b90d507c86838.diff

LOG: [VPlan] Add initial inner-loop VPlan verification.

This patch adds a function to verify general properties of VPlans. The
first check makes sure that all phi-like recipes are at the beginning of
a block, with no other recipes in between.

Note that this currently may not hold for VPBlendRecipes at the moment,
as other recipes may be inserted before the VPBlendRecipe during mask
creation.

Note that this patch depends on D111300 and D111301, which fix code that
breaks the checked invariant.

Reviewed By: Ayal

Differential Revision: https://reviews.llvm.org/D111302

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
    llvm/lib/Transforms/Vectorize/VPlanVerifier.cpp
    llvm/lib/Transforms/Vectorize/VPlanVerifier.h

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index b7e077c461df..1f1130197457 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -9560,6 +9560,7 @@ VPlanPtr LoopVectorizationPlanner::buildVPlanWithVPRecipes(
   RSO.flush();
   Plan->setName(PlanName);
 
+  assert(VPlanVerifier::verifyPlanIsValid(*Plan) && "VPlan is invalid");
   return Plan;
 }
 

diff  --git a/llvm/lib/Transforms/Vectorize/VPlanVerifier.cpp b/llvm/lib/Transforms/Vectorize/VPlanVerifier.cpp
index 6eec8d14de4a..3091527915ec 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanVerifier.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanVerifier.cpp
@@ -128,3 +128,29 @@ void VPlanVerifier::verifyHierarchicalCFG(
   assert(!TopRegion->getParent() && "VPlan Top Region should have no parent.");
   verifyRegionRec(TopRegion);
 }
+
+bool VPlanVerifier::verifyPlanIsValid(const VPlan &Plan) {
+  auto Iter = depth_first(
+      VPBlockRecursiveTraversalWrapper<const VPBlockBase *>(Plan.getEntry()));
+  for (const VPBasicBlock *VPBB :
+       VPBlockUtils::blocksOnly<const VPBasicBlock>(Iter)) {
+    // Verify that phi-like recipes are at the beginning of the block, with no
+    // other recipes in between.
+    auto RecipeI = VPBB->begin();
+    auto End = VPBB->end();
+    while (RecipeI != End && RecipeI->isPhi())
+      RecipeI++;
+
+    while (RecipeI != End) {
+      if (RecipeI->isPhi() && !isa<VPBlendRecipe>(&*RecipeI)) {
+        errs() << "Found phi-like recipe after non-phi recipe:";
+        RecipeI->dump();
+        errs() << "after\n";
+        std::prev(RecipeI)->dump();
+        return false;
+      }
+      RecipeI++;
+    }
+  }
+  return true;
+}

diff  --git a/llvm/lib/Transforms/Vectorize/VPlanVerifier.h b/llvm/lib/Transforms/Vectorize/VPlanVerifier.h
index 8e8de441648a..839c24e2c9f4 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanVerifier.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanVerifier.h
@@ -26,6 +26,7 @@
 
 namespace llvm {
 class VPRegionBlock;
+class VPlan;
 
 /// Struct with utility functions that can be used to check the consistency and
 /// invariants of a VPlan, including the components of its H-CFG.
@@ -35,6 +36,12 @@ struct VPlanVerifier {
   /// 1. Region/Block verification: Check the Region/Block verification
   /// invariants for every region in the H-CFG.
   void verifyHierarchicalCFG(const VPRegionBlock *TopRegion) const;
+
+  /// Verify invariants for general VPlans. Currently it checks the following:
+  /// 1. all phi-like recipes must be at the beginning of a block, with no other
+  /// recipes in between. Note that currently there is still an exception for
+  /// VPBlendRecipes.
+  static bool verifyPlanIsValid(const VPlan &Plan);
 };
 } // namespace llvm