move decomposeBitTestICmp() to Transforms/Utils; NFC

As noted in https://reviews.llvm.org/D22537 , we can use this functionality in visitSelectInstWithICmp() and InstSimplify, but currently we have duplicated code. llvm-svn: 276140
llvm · Jul 20, 2016 · 683170b · 683170b
1 parent 481232e
commit 683170b
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Showing 3 changed files with 49 additions and 47 deletions.
diff --git a/llvm/include/llvm/Transforms/Utils/CmpInstAnalysis.h b/llvm/include/llvm/Transforms/Utils/CmpInstAnalysis.h
@@ -60,6 +60,11 @@ namespace llvm {
   /// equality comparison (which is signless).
   bool PredicatesFoldable(CmpInst::Predicate p1, CmpInst::Predicate p2);
 
+  /// Decompose an icmp into the form ((X & Y) pred Z) if possible. The returned
+  /// predicate is either == or !=. Returns false if decomposition fails.
+  bool decomposeBitTestICmp(const ICmpInst *I, CmpInst::Predicate &Pred,
+                            Value *&X, Value *&Y, Value *&Z);
+
 } // end namespace llvm
 
 #endif
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -524,53 +524,6 @@ static unsigned conjugateICmpMask(unsigned Mask) {
   return NewMask;
 }
 
-/// Decompose an icmp into the form ((X & Y) pred Z) if possible.
-/// The returned predicate is either == or !=. Returns false if
-/// decomposition fails.
-static bool decomposeBitTestICmp(const ICmpInst *I, ICmpInst::Predicate &Pred,
-                                 Value *&X, Value *&Y, Value *&Z) {
-  ConstantInt *C = dyn_cast<ConstantInt>(I->getOperand(1));
-  if (!C)
-    return false;
-
-  switch (I->getPredicate()) {
-  default:
-    return false;
-  case ICmpInst::ICMP_SLT:
-    // X < 0 is equivalent to (X & SignBit) != 0.
-    if (!C->isZero())
-      return false;
-    Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth()));
-    Pred = ICmpInst::ICMP_NE;
-    break;
-  case ICmpInst::ICMP_SGT:
-    // X > -1 is equivalent to (X & SignBit) == 0.
-    if (!C->isAllOnesValue())
-      return false;
-    Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth()));
-    Pred = ICmpInst::ICMP_EQ;
-    break;
-  case ICmpInst::ICMP_ULT:
-    // X <u 2^n is equivalent to (X & ~(2^n-1)) == 0.
-    if (!C->getValue().isPowerOf2())
-      return false;
-    Y = ConstantInt::get(I->getContext(), -C->getValue());
-    Pred = ICmpInst::ICMP_EQ;
-    break;
-  case ICmpInst::ICMP_UGT:
-    // X >u 2^n-1 is equivalent to (X & ~(2^n-1)) != 0.
-    if (!(C->getValue() + 1).isPowerOf2())
-      return false;
-    Y = ConstantInt::get(I->getContext(), ~C->getValue());
-    Pred = ICmpInst::ICMP_NE;
-    break;
-  }
-
-  X = I->getOperand(0);
-  Z = ConstantInt::getNullValue(C->getType());
-  return true;
-}
-
 /// Handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
 /// Return the set of pattern classes (from MaskedICmpType)
 /// that both LHS and RHS satisfy.

diff --git a/llvm/lib/Transforms/Utils/CmpInstAnalysis.cpp b/llvm/lib/Transforms/Utils/CmpInstAnalysis.cpp
@@ -62,3 +62,47 @@ bool llvm::PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
          (CmpInst::isSigned(p1) && ICmpInst::isEquality(p2)) ||
          (CmpInst::isSigned(p2) && ICmpInst::isEquality(p1));
 }
+
+bool llvm::decomposeBitTestICmp(const ICmpInst *I, CmpInst::Predicate &Pred,
+                                Value *&X, Value *&Y, Value *&Z) {
+  ConstantInt *C = dyn_cast<ConstantInt>(I->getOperand(1));
+  if (!C)
+    return false;
+
+  switch (I->getPredicate()) {
+  default:
+    return false;
+  case ICmpInst::ICMP_SLT:
+    // X < 0 is equivalent to (X & SignBit) != 0.
+    if (!C->isZero())
+      return false;
+    Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth()));
+    Pred = ICmpInst::ICMP_NE;
+    break;
+  case ICmpInst::ICMP_SGT:
+    // X > -1 is equivalent to (X & SignBit) == 0.
+    if (!C->isAllOnesValue())
+      return false;
+    Y = ConstantInt::get(I->getContext(), APInt::getSignBit(C->getBitWidth()));
+    Pred = ICmpInst::ICMP_EQ;
+    break;
+  case ICmpInst::ICMP_ULT:
+    // X <u 2^n is equivalent to (X & ~(2^n-1)) == 0.
+    if (!C->getValue().isPowerOf2())
+      return false;
+    Y = ConstantInt::get(I->getContext(), -C->getValue());
+    Pred = ICmpInst::ICMP_EQ;
+    break;
+  case ICmpInst::ICMP_UGT:
+    // X >u 2^n-1 is equivalent to (X & ~(2^n-1)) != 0.
+    if (!(C->getValue() + 1).isPowerOf2())
+      return false;
+    Y = ConstantInt::get(I->getContext(), ~C->getValue());
+    Pred = ICmpInst::ICMP_NE;
+    break;
+  }
+
+  X = I->getOperand(0);
+  Z = ConstantInt::getNullValue(C->getType());
+  return true;
+}