1 files changed, 153 insertions, 0 deletions
diff --git a/contrib/llvm-project/llvm/lib/Analysis/CmpInstAnalysis.cpp b/contrib/llvm-project/llvm/lib/Analysis/CmpInstAnalysis.cpp
new file mode 100644
index 000000000000..d6407e875073
--- /dev/null
+++ b/contrib/llvm-project/llvm/lib/Analysis/CmpInstAnalysis.cpp
@@ -0,0 +1,153 @@
+//===- CmpInstAnalysis.cpp - Utils to help fold compares ---------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// 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(CmpInst::Predicate Pred) {
+  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!");
+  }
+}
+
+Constant *llvm::getPredForICmpCode(unsigned Code, bool Sign, Type *OpTy,
+                                   CmpInst::Predicate &Pred) {
+  switch (Code) {
+    default: llvm_unreachable("Illegal ICmp code!");
+    case 0: // False.
+      return ConstantInt::get(CmpInst::makeCmpResultType(OpTy), 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(OpTy), 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));
+}
+
+Constant *llvm::getPredForFCmpCode(unsigned Code, Type *OpTy,
+                                   CmpInst::Predicate &Pred) {
+  Pred = static_cast<FCmpInst::Predicate>(Code);
+  assert(FCmpInst::FCMP_FALSE <= Pred && Pred <= FCmpInst::FCMP_TRUE &&
+         "Unexpected FCmp predicate!");
+  if (Pred == FCmpInst::FCMP_FALSE)
+    return ConstantInt::get(CmpInst::makeCmpResultType(OpTy), 0);
+  if (Pred == FCmpInst::FCMP_TRUE)
+    return ConstantInt::get(CmpInst::makeCmpResultType(OpTy), 1);
+  return nullptr;
+}
+
+bool llvm::decomposeBitTestICmp(Value *LHS, Value *RHS,
+                                CmpInst::Predicate &Pred,
+                                Value *&X, APInt &Mask, bool LookThruTrunc) {
+  using namespace PatternMatch;
+
+  const APInt *C;
+  if (!match(RHS, m_APIntAllowUndef(C)))
+    return false;
+
+  switch (Pred) {
+  default:
+    return false;
+  case ICmpInst::ICMP_SLT:
+    // X < 0 is equivalent to (X & SignMask) != 0.
+    if (!C->isZero())
+      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->isAllOnes())
+      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->isAllOnes())
+      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->isZero())
+      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;
+  }
+
+  if (LookThruTrunc && match(LHS, m_Trunc(m_Value(X)))) {
+    Mask = Mask.zext(X->getType()->getScalarSizeInBits());
+  } else {
+    X = LHS;
+  }
+
+  return true;
+}