Refactor code used in InstCombine::FoldAndOfICmps to new file.

This will be used by SimplifyCfg in a later commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146803 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 175 insertions, 72 deletions

diff --git a/include/llvm/Transforms/Utils/CmpInstAnalysis.h b/include/llvm/Transforms/Utils/CmpInstAnalysis.h
new file mode 100644
index 0000000..7ad7bdd
--- /dev/null
+++ b/include/llvm/Transforms/Utils/CmpInstAnalysis.h
@@ -0,0 +1,66 @@
+//===-- CmpInstAnalysis.h - Utils to help fold compare insts ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file holds routines to help analyse compare instructions
+// and fold them into constants or other compare instructions
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_CMPINSTANALYSIS_H
+#define LLVM_TRANSFORMS_UTILS_CMPINSTANALYSIS_H
+
+#include "llvm/InstrTypes.h"
+
+namespace llvm {
+  class ICmpInst;
+  class Value;
+
+  /// getICmpCode - Encode a icmp predicate into a three bit mask.  These bits
+  /// are carefully arranged to allow folding of expressions such as:
+  ///
+  ///      (A < B) | (A > B) --> (A != B)
+  ///
+  /// Note that this is only valid if the first and second predicates have the
+  /// same sign. Is illegal to do: (A u< B) | (A s> B)
+  ///
+  /// Three bits are used to represent the condition, as follows:
+  ///   0  A > B
+  ///   1  A == B
+  ///   2  A < B
+  ///
+  /// <=>  Value  Definition
+  /// 000     0   Always false
+  /// 001     1   A >  B
+  /// 010     2   A == B
+  /// 011     3   A >= B
+  /// 100     4   A <  B
+  /// 101     5   A != B
+  /// 110     6   A <= B
+  /// 111     7   Always true
+  ///
+  unsigned getICmpCode(const ICmpInst *ICI, bool InvertPred = false);
+
+  /// getICmpValue - This is the complement of getICmpCode, which turns an
+  /// opcode and two operands into either a constant true or false, or the
+  /// predicate for a new ICmp instruction. The sign is passed in to determine
+  /// which kind of predicate to use in the new icmp instruction.
+  /// Non-NULL return value will be a true or false constant.
+  /// NULL return means a new ICmp is needed.  The predicate for which is
+  /// output in NewICmpPred.
+  Value *getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS,
+                      CmpInst::Predicate &NewICmpPred);
+
+  /// PredicatesFoldable - Return true if both predicates match sign or if at
+  /// least one of them is an equality comparison (which is signless).
+  bool PredicatesFoldable(CmpInst::Predicate p1, CmpInst::Predicate p2);
+
+} // end namespace llvm
+
+#endif
+
diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 5e0bfe8..4b1e7fe 100644
--- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -14,6 +14,7 @@
 #include "InstCombine.h"
 #include "llvm/Intrinsics.h"
 #include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Transforms/Utils/CmpInstAnalysis.h"
 #include "llvm/Support/ConstantRange.h"
 #include "llvm/Support/PatternMatch.h"
 using namespace llvm;
@@ -62,50 +63,6 @@ static inline Value *dyn_castNotVal(Value *V) {
   return 0;
 }
 
-
-/// getICmpCode - Encode a icmp predicate into a three bit mask.  These bits
-/// are carefully arranged to allow folding of expressions such as:
-///
-///      (A < B) | (A > B) --> (A != B)
-///
-/// Note that this is only valid if the first and second predicates have the
-/// same sign. Is illegal to do: (A u< B) | (A s> B) 
-///
-/// Three bits are used to represent the condition, as follows:
-///   0  A > B
-///   1  A == B
-///   2  A < B
-///
-/// <=>  Value  Definition
-/// 000     0   Always false
-/// 001     1   A >  B
-/// 010     2   A == B
-/// 011     3   A >= B
-/// 100     4   A <  B
-/// 101     5   A != B
-/// 110     6   A <= B
-/// 111     7   Always true
-///  
-static unsigned getICmpCode(const ICmpInst *ICI) {
-  switch (ICI->getPredicate()) {
-    // False -> 0
-  case ICmpInst::ICMP_UGT: return 1;  // 001
-  case ICmpInst::ICMP_SGT: return 1;  // 001
-  case ICmpInst::ICMP_EQ:  return 2;  // 010
-  case ICmpInst::ICMP_UGE: return 3;  // 011
-  case ICmpInst::ICMP_SGE: return 3;  // 011
-  case ICmpInst::ICMP_ULT: return 4;  // 100
-  case ICmpInst::ICMP_SLT: return 4;  // 100
-  case ICmpInst::ICMP_NE:  return 5;  // 101
-  case ICmpInst::ICMP_ULE: return 6;  // 110
-  case ICmpInst::ICMP_SLE: return 6;  // 110
-    // True -> 7
-  default:
-    llvm_unreachable("Invalid ICmp predicate!");
-    return 0;
-  }
-}
-
 /// getFCmpCode - Similar to getICmpCode but for FCmpInst. This encodes a fcmp
 /// predicate into a three bit mask. It also returns whether it is an ordered
 /// predicate by reference.
@@ -138,23 +95,12 @@ static unsigned getFCmpCode(FCmpInst::Predicate CC, bool &isOrdered) {
 /// opcode and two operands into either a constant true or false, or a brand 
 /// new ICmp instruction. The sign is passed in to determine which kind
 /// of predicate to use in the new icmp instruction.
-static Value *getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS,
-                           InstCombiner::BuilderTy *Builder) {
-  CmpInst::Predicate Pred;
-  switch (Code) {
-  default: assert(0 && "Illegal ICmp code!");
-  case 0: // False.
-    return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
-  case 1: Pred = Sign ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; break;
-  case 2: Pred = ICmpInst::ICMP_EQ; break;
-  case 3: Pred = Sign ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; break;
-  case 4: Pred = Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; break;
-  case 5: Pred = ICmpInst::ICMP_NE; break;
-  case 6: Pred = Sign ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; break;
-  case 7: // True.
-    return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1);
-  }
-  return Builder->CreateICmp(Pred, LHS, RHS);
+Value *getNewICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS,
+                    InstCombiner::BuilderTy *Builder) {
+  ICmpInst::Predicate NewPred;
+  if (Value *NewConstant = getICmpValue(Sign, Code, LHS, RHS, NewPred))
+    return NewConstant;
+  return Builder->CreateICmp(NewPred, LHS, RHS);
 }
 
 /// getFCmpValue - This is the complement of getFCmpCode, which turns an
@@ -180,14 +126,6 @@ static Value *getFCmpValue(bool isordered, unsigned code,
   return Builder->CreateFCmp(Pred, LHS, RHS);
 }
 
-/// PredicatesFoldable - Return true if both predicates match sign or if at
-/// least one of them is an equality comparison (which is signless).
-static bool PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
-  return (CmpInst::isSigned(p1) == CmpInst::isSigned(p2)) ||
-         (CmpInst::isSigned(p1) && ICmpInst::isEquality(p2)) ||
-         (CmpInst::isSigned(p2) && ICmpInst::isEquality(p1));
-}
-
 // OptAndOp - This handles expressions of the form ((val OP C1) & C2).  Where
 // the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'.  Op is
 // guaranteed to be a binary operator.
@@ -728,7 +666,7 @@ Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
       Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
       unsigned Code = getICmpCode(LHS) & getICmpCode(RHS);
       bool isSigned = LHS->isSigned() || RHS->isSigned();
-      return getICmpValue(isSigned, Code, Op0, Op1, Builder);
+      return getNewICmpValue(isSigned, Code, Op0, Op1, Builder);
     }
   }
 
@@ -1469,7 +1407,7 @@ Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
       Value *Op0 = LHS->getOperand(0), *Op1 = LHS->getOperand(1);
       unsigned Code = getICmpCode(LHS) | getICmpCode(RHS);
       bool isSigned = LHS->isSigned() || RHS->isSigned();
-      return getICmpValue(isSigned, Code, Op0, Op1, Builder);
+      return getNewICmpValue(isSigned, Code, Op0, Op1, Builder);
     }
   }
 
@@ -2281,7 +2219,8 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
           unsigned Code = getICmpCode(LHS) ^ getICmpCode(RHS);
           bool isSigned = LHS->isSigned() || RHS->isSigned();
           return ReplaceInstUsesWith(I, 
-                               getICmpValue(isSigned, Code, Op0, Op1, Builder));
+                               getNewICmpValue(isSigned, Code, Op0, Op1,
+                                               Builder));
         }
       }
 
diff --git a/lib/Transforms/Utils/CMakeLists.txt b/lib/Transforms/Utils/CMakeLists.txt
index d96f59c..d1aa599 100644
--- a/lib/Transforms/Utils/CMakeLists.txt
+++ b/lib/Transforms/Utils/CMakeLists.txt
@@ -6,6 +6,7 @@ add_llvm_library(LLVMTransformUtils
   BuildLibCalls.cpp
   CloneFunction.cpp
   CloneModule.cpp
+  CmpInstAnalysis.cpp
   CodeExtractor.cpp
   DemoteRegToStack.cpp
   InlineFunction.cpp
diff --git a/lib/Transforms/Utils/CmpInstAnalysis.cpp b/lib/Transforms/Utils/CmpInstAnalysis.cpp
new file mode 100644
index 0000000..e336e9a
--- /dev/null
+++ b/lib/Transforms/Utils/CmpInstAnalysis.cpp
@@ -0,0 +1,97 @@
+//===- CmpInstAnalysis.cpp - Utils to help fold compares ---------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file holds routines to help analyse compare instructions
+// and fold them into constants or other compare instructions
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/CmpInstAnalysis.h"
+#include "llvm/Constants.h"
+#include "llvm/Instructions.h"
+
+using namespace llvm;
+
+/// getICmpCode - Encode a icmp predicate into a three bit mask.  These bits
+/// are carefully arranged to allow folding of expressions such as:
+///
+///      (A < B) | (A > B) --> (A != B)
+///
+/// Note that this is only valid if the first and second predicates have the
+/// same sign. Is illegal to do: (A u< B) | (A s> B)
+///
+/// Three bits are used to represent the condition, as follows:
+///   0  A > B
+///   1  A == B
+///   2  A < B
+///
+/// <=>  Value  Definition
+/// 000     0   Always false
+/// 001     1   A >  B
+/// 010     2   A == B
+/// 011     3   A >= B
+/// 100     4   A <  B
+/// 101     5   A != B
+/// 110     6   A <= B
+/// 111     7   Always true
+///
+unsigned llvm::getICmpCode(const ICmpInst *ICI, bool InvertPred) {
+  ICmpInst::Predicate Pred = InvertPred ? ICI->getInversePredicate()
+                                        : ICI->getPredicate();
+  switch (Pred) {
+      // False -> 0
+    case ICmpInst::ICMP_UGT: return 1;  // 001
+    case ICmpInst::ICMP_SGT: return 1;  // 001
+    case ICmpInst::ICMP_EQ:  return 2;  // 010
+    case ICmpInst::ICMP_UGE: return 3;  // 011
+    case ICmpInst::ICMP_SGE: return 3;  // 011
+    case ICmpInst::ICMP_ULT: return 4;  // 100
+    case ICmpInst::ICMP_SLT: return 4;  // 100
+    case ICmpInst::ICMP_NE:  return 5;  // 101
+    case ICmpInst::ICMP_ULE: return 6;  // 110
+    case ICmpInst::ICMP_SLE: return 6;  // 110
+      // True -> 7
+    default:
+      llvm_unreachable("Invalid ICmp predicate!");
+      return 0;
+  }
+}
+
+/// getICmpValue - This is the complement of getICmpCode, which turns an
+/// opcode and two operands into either a constant true or false, or the
+/// predicate for a new ICmp instruction. The sign is passed in to determine
+/// which kind of predicate to use in the new icmp instruction.
+/// Non-NULL return value will be a true or false constant.
+/// NULL return means a new ICmp is needed.  The predicate for which is
+/// output in NewICmpPred.
+Value *llvm::getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS,
+                          CmpInst::Predicate &NewICmpPred) {
+  switch (Code) {
+    default: assert(0 && "Illegal ICmp code!");
+    case 0: // False.
+      return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
+    case 1: NewICmpPred = Sign ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; break;
+    case 2: NewICmpPred = ICmpInst::ICMP_EQ; break;
+    case 3: NewICmpPred = Sign ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; break;
+    case 4: NewICmpPred = Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; break;
+    case 5: NewICmpPred = ICmpInst::ICMP_NE; break;
+    case 6: NewICmpPred = Sign ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; break;
+    case 7: // True.
+      return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1);
+  }
+  return NULL;
+}
+
+/// PredicatesFoldable - Return true if both predicates match sign or if at
+/// least one of them is an equality comparison (which is signless).
+bool llvm::PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
+  return (CmpInst::isSigned(p1) == CmpInst::isSigned(p2)) ||
+         (CmpInst::isSigned(p1) && ICmpInst::isEquality(p2)) ||
+         (CmpInst::isSigned(p2) && ICmpInst::isEquality(p1));
+}