Move some constant folding functions into LLVMAnalysis since they are used

by Analysis and Transformation passes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24038 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 172 insertions, 0 deletions

diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
new file mode 100644
index 0000000..4022bdd
--- /dev/null
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -0,0 +1,172 @@
+//===-- ConstantFolding.cpp - Analyze constant folding possibilities ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This family of functions determines the possibility of performing constant
+// folding.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Instructions.h"
+#include "llvm/Intrinsics.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Support/MathExtras.h"
+#include <cerrno>
+#include <cmath>
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+//  Constant Folding ...
+//
+
+
+/// canConstantFoldCallTo - Return true if its even possible to fold a call to
+/// the specified function.
+bool
+llvm::canConstantFoldCallTo(Function *F) {
+  const std::string &Name = F->getName();
+
+  switch (F->getIntrinsicID()) {
+  case Intrinsic::isunordered:
+  case Intrinsic::sqrt:
+    return true;
+  default: break;
+  }
+
+  switch (Name[0])
+  {
+    case 'a':
+      return Name == "acos" || Name == "asin" || Name == "atan" ||
+             Name == "atan2";
+    case 'c':
+      return Name == "ceil" || Name == "cos" || Name == "cosf" ||
+             Name == "cosh";
+    case 'e':
+      return Name == "exp";
+    case 'f':
+      return Name == "fabs" || Name == "fmod" || Name == "floor";
+    case 'l':
+      return Name == "log" || Name == "log10";
+    case 'p':
+      return Name == "pow";
+    case 's':
+      return Name == "sin" || Name == "sinh" || Name == "sqrt";
+    case 't':
+      return Name == "tan" || Name == "tanh";
+    default:
+      return false;
+  }
+}
+
+Constant *
+llvm::ConstantFoldFP(double (*NativeFP)(double), double V, const Type *Ty) {
+  errno = 0;
+  V = NativeFP(V);
+  if (errno == 0)
+    return ConstantFP::get(Ty, V);
+  return 0;
+}
+
+/// ConstantFoldCall - Attempt to constant fold a call to the specified function
+/// with the specified arguments, returning null if unsuccessful.
+Constant *
+llvm::ConstantFoldCall(Function *F, const std::vector<Constant*> &Operands) {
+  const std::string &Name = F->getName();
+  const Type *Ty = F->getReturnType();
+
+  if (Operands.size() == 1) {
+    if (ConstantFP *Op = dyn_cast<ConstantFP>(Operands[0])) {
+      double V = Op->getValue();
+      switch (Name[0])
+      {
+        case 'a':
+          if (Name == "acos")
+            return ConstantFoldFP(acos, V, Ty);
+          else if (Name == "asin")
+            return ConstantFoldFP(asin, V, Ty);
+          else if (Name == "atan")
+            return ConstantFP::get(Ty, atan(V));
+          break;
+        case 'c':
+          if (Name == "ceil")
+            return ConstantFoldFP(ceil, V, Ty);
+          else if (Name == "cos")
+            return ConstantFP::get(Ty, cos(V));
+          else if (Name == "cosh")
+            return ConstantFP::get(Ty, cosh(V));
+          break;
+        case 'e':
+          if (Name == "exp")
+            return ConstantFP::get(Ty, exp(V));
+          break;
+        case 'f':
+          if (Name == "fabs")
+            return ConstantFP::get(Ty, fabs(V));
+          else if (Name == "floor")
+            return ConstantFoldFP(floor, V, Ty);
+          break;
+        case 'l':
+          if (Name == "log" && V > 0)
+            return ConstantFP::get(Ty, log(V));
+          else if (Name == "log10" && V > 0)
+            return ConstantFoldFP(log10, V, Ty);
+          else if (Name == "llvm.sqrt") {
+            if (V >= -0.0)
+              return ConstantFP::get(Ty, sqrt(V));
+            else // Undefined
+              return ConstantFP::get(Ty, 0.0);
+          }
+          break;
+        case 's':
+          if (Name == "sin")
+            return ConstantFP::get(Ty, sin(V));
+          else if (Name == "sinh")
+            return ConstantFP::get(Ty, sinh(V));
+          else if (Name == "sqrt" && V >= 0)
+            return ConstantFP::get(Ty, sqrt(V));
+          break;
+        case 't':
+          if (Name == "tan")
+            return ConstantFP::get(Ty, tan(V));
+          else if (Name == "tanh")
+            return ConstantFP::get(Ty, tanh(V));
+          break;
+        default:
+          break;
+      }
+    }
+  } else if (Operands.size() == 2) {
+    if (ConstantFP *Op1 = dyn_cast<ConstantFP>(Operands[0])) {
+      double Op1V = Op1->getValue();
+      if (ConstantFP *Op2 = dyn_cast<ConstantFP>(Operands[1])) {
+        double Op2V = Op2->getValue();
+
+        if (Name == "llvm.isunordered")
+          return ConstantBool::get(IsNAN(Op1V) || IsNAN(Op2V));
+        else
+        if (Name == "pow") {
+          errno = 0;
+          double V = pow(Op1V, Op2V);
+          if (errno == 0)
+            return ConstantFP::get(Ty, V);
+        } else if (Name == "fmod") {
+          errno = 0;
+          double V = fmod(Op1V, Op2V);
+          if (errno == 0)
+            return ConstantFP::get(Ty, V);
+        } else if (Name == "atan2")
+          return ConstantFP::get(Ty, atan2(Op1V,Op2V));
+      }
+    }
+  }
+  return 0;
+}
+