[InstCombine][InstSimplify] 'git add' two files that moved in r310869.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310870 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/CmpInstAnalysis.h b/include/llvm/Analysis/CmpInstAnalysis.h
new file mode 100644 (file)
index 0000000..1079d5a
--- /dev/null
+++ b/include/llvm/Analysis/CmpInstAnalysis.h
@@ -0,0 +1,71 @@
+//===-- CmpInstAnalysis.h - Utils to help fold compare insts ----*- C++ -*-===//
+//
+//                     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_ANALYSIS_CMPINSTANALYSIS_H
+#define LLVM_ANALYSIS_CMPINSTANALYSIS_H
+
+#include "llvm/IR/InstrTypes.h"
+
+namespace llvm {
+  class ICmpInst;
+  class Value;
+
+  /// 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. It 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);
+
+  /// 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);
+
+  /// 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);
+
+  /// Decompose an icmp into the form ((X & Mask) pred 0) if possible. The
+  /// returned predicate is either == or !=. Returns false if decomposition
+  /// fails.
+  bool decomposeBitTestICmp(Value *LHS, Value *RHS, CmpInst::Predicate &Pred,
+                            Value *&X, APInt &Mask);
+
+} // end namespace llvm
+
+#endif

diff --git a/lib/Analysis/CmpInstAnalysis.cpp b/lib/Analysis/CmpInstAnalysis.cpp
new file mode 100644 (file)
index 0000000..c879b87
--- /dev/null
+++ b/lib/Analysis/CmpInstAnalysis.cpp
@@ -0,0 +1,137 @@
+//===- 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/Analysis/CmpInstAnalysis.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/PatternMatch.h"
+
+using namespace llvm;
+
+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!");
+  }
+}
+
+Value *llvm::getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS,
+                          CmpInst::Predicate &NewICmpPred) {
+  switch (Code) {
+    default: llvm_unreachable("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 nullptr;
+}
+
+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));
+}
+
+bool llvm::decomposeBitTestICmp(Value *LHS, Value *RHS,
+                                CmpInst::Predicate &Pred,
+                                Value *&X, APInt &Mask) {
+  const APInt *C;
+  if (!match(RHS, PatternMatch::m_APInt(C)))
+    return false;
+
+  switch (Pred) {
+  default:
+    return false;
+  case ICmpInst::ICMP_SLT:
+    // X < 0 is equivalent to (X & SignMask) != 0.
+    if (!C->isNullValue())
+      return false;
+    Mask = APInt::getSignMask(C->getBitWidth());
+    Pred = ICmpInst::ICMP_NE;
+    break;
+  case ICmpInst::ICMP_SLE:
+    // X <= -1 is equivalent to (X & SignMask) != 0.
+    if (!C->isAllOnesValue())
+      return false;
+    Mask = APInt::getSignMask(C->getBitWidth());
+    Pred = ICmpInst::ICMP_NE;
+    break;
+  case ICmpInst::ICMP_SGT:
+    // X > -1 is equivalent to (X & SignMask) == 0.
+    if (!C->isAllOnesValue())
+      return false;
+    Mask = APInt::getSignMask(C->getBitWidth());
+    Pred = ICmpInst::ICMP_EQ;
+    break;
+  case ICmpInst::ICMP_SGE:
+    // X >= 0 is equivalent to (X & SignMask) == 0.
+    if (!C->isNullValue())
+      return false;
+    Mask = APInt::getSignMask(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->isPowerOf2())
+      return false;
+    Mask = -*C;
+    Pred = ICmpInst::ICMP_EQ;
+    break;
+  case ICmpInst::ICMP_ULE:
+    // X <=u 2^n-1 is equivalent to (X & ~(2^n-1)) == 0.
+    if (!(*C + 1).isPowerOf2())
+      return false;
+    Mask = ~*C;
+    Pred = ICmpInst::ICMP_EQ;
+    break;
+  case ICmpInst::ICMP_UGT:
+    // X >u 2^n-1 is equivalent to (X & ~(2^n-1)) != 0.
+    if (!(*C + 1).isPowerOf2())
+      return false;
+    Mask = ~*C;
+    Pred = ICmpInst::ICMP_NE;
+    break;
+  case ICmpInst::ICMP_UGE:
+    // X >=u 2^n is equivalent to (X & ~(2^n-1)) != 0.
+    if (!C->isPowerOf2())
+      return false;
+    Mask = -*C;
+    Pred = ICmpInst::ICMP_NE;
+    break;
+  }
+
+  X = LHS;
+  return true;
+}