[PATCH] D148744: [InstCombine] Refactor foldSelectICmpAndOr to use `decomposeBitTestICmp` instead of bespoke logic

[Noah Goldstein via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG00f03814611e: [InstCombine] Refactor foldSelectICmpAndOr to use `decomposeBitTestICmp`… (authored by goldstein.w.n).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D148744/new/

https://reviews.llvm.org/D148744

Files:
  llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp


Index: llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -714,8 +714,8 @@
   Value *CmpRHS = IC->getOperand(1);
 
   unsigned C1Log;
-  bool IsEqualZero;
   bool NeedAnd = false;
+  CmpInst::Predicate Pred = IC->getPredicate();
   if (IC->isEquality()) {
     if (!match(CmpRHS, m_Zero()))
       return nullptr;
@@ -725,17 +725,13 @@
       return nullptr;
 
     C1Log = C1->logBase2();
-    IsEqualZero = IC->getPredicate() == ICmpInst::ICMP_EQ;
   } else {
-    // We also need to recognize (icmp slt X, 0) and (icmp sgt X, -1).
-    if (IC->getPredicate() == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes()))
-      IsEqualZero = true;
-    if (IC->getPredicate() == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero()))
-      IsEqualZero = false;
-    else
+    APInt C1;
+    if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, CmpLHS, C1) ||
+        !C1.isPowerOf2())
       return nullptr;
 
-    C1Log = CmpLHS->getType()->getScalarSizeInBits() - 1;
+    C1Log = C1.logBase2();
     NeedAnd = true;
   }
 
@@ -745,11 +741,11 @@
   if (match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2)))) {
     Y = TrueVal;
     Or = FalseVal;
-    NeedXor = !IsEqualZero;
+    NeedXor = Pred == ICmpInst::ICMP_NE;
   } else if (match(TrueVal, m_Or(m_Specific(FalseVal), m_Power2(C2)))) {
     Y = FalseVal;
     Or = TrueVal;
-    NeedXor = IsEqualZero;
+    NeedXor = Pred == ICmpInst::ICMP_EQ;
   } else {
     return nullptr;
   }


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