[llvm] 3050713 - [Attributor] Provide an edge-based interface in AAIsDead

[Shinji Okumura via llvm-commits]

Author: Shinji Okumura
Date: 2020-08-26T16:57:52+09:00
New Revision: 30507137986ab5d27c82c024dff1ffbf51ee9b31

URL: https://github.com/llvm/llvm-project/commit/30507137986ab5d27c82c024dff1ffbf51ee9b31
DIFF: https://github.com/llvm/llvm-project/commit/30507137986ab5d27c82c024dff1ffbf51ee9b31.diff

LOG: [Attributor] Provide an edge-based interface in AAIsDead

This patch produces an edge-based interface in AAIsDead.
By this, we can query a set of basic blocks that are directly reachable from a given basic block.
This is specifically useful for implementation of AAReachability.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D85547

Added: 
    

Modified: 
    llvm/include/llvm/Transforms/IPO/Attributor.h
    llvm/lib/Transforms/IPO/AttributorAttributes.cpp

Removed: 
    


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diff  --git a/llvm/include/llvm/Transforms/IPO/Attributor.h b/llvm/include/llvm/Transforms/IPO/Attributor.h
index 73e25417452c..2dfb2b189046 100644
--- a/llvm/include/llvm/Transforms/IPO/Attributor.h
+++ b/llvm/include/llvm/Transforms/IPO/Attributor.h
@@ -2646,6 +2646,12 @@ struct AAIsDead : public StateWrapper<BooleanState, AbstractAttribute> {
     return F.hasPersonalityFn() && !canSimplifyInvokeNoUnwind(&F);
   }
 
+  /// Return if the edge from \p From BB to \p To BB is assumed dead.
+  /// This is specifically useful in AAReachability.
+  virtual bool isEdgeDead(const BasicBlock *From, const BasicBlock *To) const {
+    return false;
+  }
+
   /// See AbstractAttribute::getName()
   const std::string getName() const override { return "AAIsDead"; }
 

diff  --git a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
index 8a83e7f05220..33952a836e25 100644
--- a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -3093,6 +3093,10 @@ struct AAIsDeadFunction : public AAIsDead {
   /// See AbstractAttribute::updateImpl(...).
   ChangeStatus updateImpl(Attributor &A) override;
 
+  bool isEdgeDead(const BasicBlock *From, const BasicBlock *To) const override {
+    return !AssumedLiveEdges.count(std::make_pair(From, To));
+  }
+
   /// See AbstractAttribute::trackStatistics()
   void trackStatistics() const override {}
 
@@ -3170,6 +3174,9 @@ struct AAIsDeadFunction : public AAIsDead {
   /// Collection of instructions that are known to not transfer control.
   SmallSetVector<const Instruction *, 8> KnownDeadEnds;
 
+  /// Collection of all assumed live edges
+  DenseSet<std::pair<const BasicBlock *, const BasicBlock *>> AssumedLiveEdges;
+
   /// Collection of all assumed live BasicBlocks.
   DenseSet<const BasicBlock *> AssumedLiveBlocks;
 };
@@ -3340,6 +3347,9 @@ ChangeStatus AAIsDeadFunction::updateImpl(Attributor &A) {
                "Non-terminator expected to have a single successor!");
         Worklist.push_back(AliveSuccessor);
       } else {
+        // record the assumed live edge
+        AssumedLiveEdges.insert(
+            std::make_pair(I->getParent(), AliveSuccessor->getParent()));
         if (assumeLive(A, *AliveSuccessor->getParent()))
           Worklist.push_back(AliveSuccessor);
       }