[llvm] 304a5a7 - Revert "[ValueTracking] Added support to deduce PHI Nodes values being a power of 2"

[Nico Weber via llvm-commits]

Author: Nico Weber
Date: 2022-05-19T15:05:30-04:00
New Revision: 304a5a7a14dd26ae93194b336fef9a1213fa44b5

URL: https://github.com/llvm/llvm-project/commit/304a5a7a14dd26ae93194b336fef9a1213fa44b5
DIFF: https://github.com/llvm/llvm-project/commit/304a5a7a14dd26ae93194b336fef9a1213fa44b5.diff

LOG: Revert "[ValueTracking] Added support to deduce PHI Nodes values being a power of 2"

This reverts commit d5c130f17e503e128b8a413c2ce0e522987d2a16.
Breaks tests, see https://reviews.llvm.org/D125332#3525819

Added: 
    

Modified: 
    llvm/lib/Analysis/ValueTracking.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 60dbfaa64460c..a32633589c94a 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -2128,25 +2128,6 @@ bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero, unsigned Depth,
     }
   }
 
-  // A PHI node is power of two if all incoming values are power of two.
-  if (const PHINode *PN = dyn_cast<PHINode>(V)) {
-    Query RecQ = Q;
-
-    // Recursively check all incoming values. Limit recursion to 2 levels, so
-    // that search complexity is limited to number of operands^2.
-    unsigned NewDepth = std::max(Depth, MaxAnalysisRecursionDepth - 1);
-    return llvm::all_of(PN->operands(), [&](const Use &U) {
-      // Value is power of 2 if it is coming from PHI node itself by induction.
-      if (U.get() == PN)
-        return true;
-
-      // Change the context instruction to the incoming block where it is
-      // evaluated.
-      RecQ.CxtI = PN->getIncomingBlock(U)->getTerminator();
-      return isKnownToBeAPowerOfTwo(U.get(), OrZero, NewDepth, RecQ);
-    });
-  }
-
   // An exact divide or right shift can only shift off zero bits, so the result
   // is a power of two only if the first operand is a power of two and not
   // copying a sign bit (sdiv int_min, 2).