[llvm] 1d5d074 - [Attributor] Reach optimistic fixpoint in AAValueSimplify when the value is constant or undef

[Hideto Ueno via llvm-commits]

Author: Hideto Ueno
Date: 2019-12-25T14:18:34+09:00
New Revision: 1d5d074aef2a92e9db8f8dabf60281c1da8baa99

URL: https://github.com/llvm/llvm-project/commit/1d5d074aef2a92e9db8f8dabf60281c1da8baa99
DIFF: https://github.com/llvm/llvm-project/commit/1d5d074aef2a92e9db8f8dabf60281c1da8baa99.diff

LOG:  [Attributor] Reach optimistic fixpoint in AAValueSimplify when the value is constant or undef

Summary:
As discussed in D71799, we have found that it is more useful to reach an optimistic fixpoint in AAValueSimpify when the value is constant or undef.

Reviewers: jdoerfert, sstefan1

Reviewed By: jdoerfert

Subscribers: baziotis, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71852

Added: 
    

Modified: 
    llvm/lib/Transforms/IPO/Attributor.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index b08bc1fda65c..deb11011f8e4 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -4072,6 +4072,14 @@ struct AAValueSimplifyImpl : AAValueSimplify {
     return Changed | AAValueSimplify::manifest(A);
   }
 
+  /// See AbstractState::indicatePessimisticFixpoint(...).
+  ChangeStatus indicatePessimisticFixpoint() override {
+    // NOTE: Associated value will be returned in a pessimistic fixpoint and is
+    // regarded as known. That's why`indicateOptimisticFixpoint` is called.
+    SimplifiedAssociatedValue = &getAssociatedValue();
+    return indicateOptimisticFixpoint();
+  }
+
 protected:
   // An assumed simplified value. Initially, it is set to Optional::None, which
   // means that the value is not clear under current assumption. If in the
@@ -4171,7 +4179,7 @@ struct AAValueSimplifyFloating : AAValueSimplifyImpl {
     Value &V = getAnchorValue();
 
     // TODO: add other stuffs
-    if (isa<Constant>(V) || isa<UndefValue>(V))
+    if (isa<Constant>(V))
       indicatePessimisticFixpoint();
   }