[PATCH] D138700: [InstSimplify] Fold (X || Y) ? false && X --> false

[chenglin.bi via Phabricator via llvm-commits]

bcl5980 updated this revision to Diff 478299.
bcl5980 retitled this revision from "[InstSimplify] Fold !(X || Y) && X --> false" to "[InstSimplify] Fold (X || Y) ? false && X --> false".
bcl5980 edited the summary of this revision.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D138700/new/

https://reviews.llvm.org/D138700

Files:
  llvm/lib/Analysis/InstructionSimplify.cpp
  llvm/test/Transforms/InstSimplify/select-logical.ll


Index: llvm/test/Transforms/InstSimplify/select-logical.ll
===================================================================
--- llvm/test/Transforms/InstSimplify/select-logical.ll
+++ llvm/test/Transforms/InstSimplify/select-logical.ll
@@ -198,46 +198,40 @@
 }
 
 
-; another way for !(X || Y) && X --> false
+; (X || Y) ? false && X --> false
 
 define i1 @logical_not_or_and_case2(i1 %x, i1 %y) {
 ; CHECK-LABEL: @logical_not_or_and_case2(
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = select i1 [[OR]], i1 false, i1 [[X]]
-; CHECK-NEXT:    ret i1 [[R]]
+; CHECK-NEXT:    ret i1 false
 ;
   %or = or i1 %x, %y
   %r = select i1 %or, i1 false, i1 %x
   ret i1 %r
 }
 
-; another way for !(X || Y) && Y --> false
+; (X || Y) ? false && X --> false
 
 define i1 @logical_not_or_and_case3(i1 %x, i1 %y) {
 ; CHECK-LABEL: @logical_not_or_and_case3(
-; CHECK-NEXT:    [[OR:%.*]] = or i1 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = select i1 [[OR]], i1 false, i1 [[Y]]
-; CHECK-NEXT:    ret i1 [[R]]
+; CHECK-NEXT:    ret i1 false
 ;
   %or = or i1 %x, %y
   %r = select i1 %or, i1 false, i1 %y
   ret i1 %r
 }
 
-; vector case !(X || Y) && X --> false
+; vector case (X || Y) ? false && X --> false
 
 define <2 x i1> @logical_not_or_and_vector2(<2 x i1> %x, <2 x i1> %y) {
 ; CHECK-LABEL: @logical_not_or_and_vector2(
-; CHECK-NEXT:    [[OR:%.*]] = or <2 x i1> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = select <2 x i1> [[OR]], <2 x i1> zeroinitializer, <2 x i1> [[X]]
-; CHECK-NEXT:    ret <2 x i1> [[R]]
+; CHECK-NEXT:    ret <2 x i1> zeroinitializer
 ;
   %or = or <2 x i1> %x, %y
   %r = select <2 x i1> %or, <2 x i1> <i1 false, i1 false>, <2 x i1> %x
   ret <2 x i1> %r
 }
 
-; vector case !(X || Y) && X --> false
+; vector poison case (X || Y) ? false && X --> false
 
 define <2 x i1> @logical_not_or_and_vector2_poison(<2 x i1> %x, <2 x i1> %y) {
 ; CHECK-LABEL: @logical_not_or_and_vector2_poison(
Index: llvm/lib/Analysis/InstructionSimplify.cpp
===================================================================
--- llvm/lib/Analysis/InstructionSimplify.cpp
+++ llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4555,9 +4555,16 @@
     if (match(TrueVal, m_One()) && match(FalseVal, m_ZeroInt()))
       return Cond;
 
-    // (X || Y) && (X || !Y) --> X (commuted 8 ways)
     Value *X, *Y;
+    if (match(Cond, m_LogicalOr(m_Value(X), m_Value(Y)))) {
+      auto *C = dyn_cast<Constant>(TrueVal);
+      // (X || Y) ? false : X --> false (commuted 2 ways)
+      if (C && C->isNullValue() && (X == FalseVal || Y == FalseVal))
+        return TrueVal;
+    }
+
     if (match(FalseVal, m_ZeroInt())) {
+      // (X || Y) && (X || !Y) --> X (commuted 8 ways)
       if (match(Cond, m_c_LogicalOr(m_Value(X), m_Not(m_Value(Y)))) &&
           match(TrueVal, m_c_LogicalOr(m_Specific(X), m_Specific(Y))))
         return X;


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