From 6bbcba18db6d1f4bc0f0157df41cc02627bc4aa9 Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Wed, 24 Jun 2009 00:54:57 +0000
Subject: [PATCH] Move the special cases for constants out of getUnknown and
 into createSCEV. Also, recognize UndefValue in createSCEV.

Change getIntegerSCEV's comment to avoid mentioning FP types,
and re-implement it in terms of getConstant instead of getUnknown.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74041 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Analysis/ScalarEvolution.h     |  2 +-
 lib/Analysis/ScalarEvolution.cpp            | 29 ++++++++++-----------
 lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp |  2 +-
 3 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/include/llvm/Analysis/ScalarEvolution.h b/include/llvm/Analysis/ScalarEvolution.h
index 311d0d03e00..cc9f9ccd553 100644
--- a/include/llvm/Analysis/ScalarEvolution.h
+++ b/include/llvm/Analysis/ScalarEvolution.h
@@ -462,7 +462,7 @@ namespace llvm {
     /// widening.
     const SCEV* getTruncateOrNoop(const SCEV* V, const Type *Ty);
 
-    /// getIntegerSCEV - Given an integer or FP type, create a constant for the
+    /// getIntegerSCEV - Given a SCEVable type, create a constant for the
     /// specified signed integer value and return a SCEV for the constant.
     const SCEV* getIntegerSCEV(int Val, const Type *Ty);
 
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 50137fad674..7abd0a5fa44 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -1867,10 +1867,11 @@ const SCEV* ScalarEvolution::getUMinExpr(const SCEV* LHS,
 }
 
 const SCEV* ScalarEvolution::getUnknown(Value *V) {
-  if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
-    return getConstant(CI);
-  if (isa<ConstantPointerNull>(V))
-    return getIntegerSCEV(0, V->getType());
+  // Don't attempt to do anything other than create a SCEVUnknown object
+  // here.  createSCEV only calls getUnknown after checking for all other
+  // interesting possibilities, and any other code that calls getUnknown
+  // is doing so in order to hide a value from SCEV canonicalization.
+
   SCEVUnknown *&Result = SCEVUnknowns[V];
   if (Result == 0) Result = new SCEVUnknown(V);
   return Result;
@@ -1948,19 +1949,11 @@ const SCEV* ScalarEvolution::getSCEV(Value *V) {
   return S;
 }
 
-/// getIntegerSCEV - Given an integer or FP type, create a constant for the
+/// getIntegerSCEV - Given a SCEVable type, create a constant for the
 /// specified signed integer value and return a SCEV for the constant.
 const SCEV* ScalarEvolution::getIntegerSCEV(int Val, const Type *Ty) {
-  Ty = getEffectiveSCEVType(Ty);
-  Constant *C;
-  if (Val == 0)
-    C = Constant::getNullValue(Ty);
-  else if (Ty->isFloatingPoint())
-    C = ConstantFP::get(APFloat(Ty==Type::FloatTy ? APFloat::IEEEsingle :
-                                APFloat::IEEEdouble, Val));
-  else
-    C = ConstantInt::get(Ty, Val);
-  return getUnknown(C);
+  const IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
+  return getConstant(ConstantInt::get(ITy, Val));
 }
 
 /// getNegativeSCEV - Return a SCEV corresponding to -V = -1*V
@@ -2429,6 +2422,12 @@ const SCEV* ScalarEvolution::createSCEV(Value *V) {
     Opcode = I->getOpcode();
   else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
     Opcode = CE->getOpcode();
+  else if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
+    return getConstant(CI);
+  else if (isa<ConstantPointerNull>(V))
+    return getIntegerSCEV(0, V->getType());
+  else if (isa<UndefValue>(V))
+    return getIntegerSCEV(0, V->getType());
   else
     return getUnknown(V);
 
diff --git a/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp b/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp
index 78d32243727..704d387cc88 100644
--- a/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp
+++ b/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp
@@ -644,7 +644,7 @@ ARMAsmPrinter::printBitfieldInvMaskImmOperand(const MachineInstr *MI, int Op) {
   const MachineOperand &MO = MI->getOperand(Op);
   uint32_t v = ~MO.getImm();
   int32_t lsb = ffs (v) - 1;
-  int32_t width = fls (v) - lsb;
+  int32_t width = ffs (v) - lsb;
   assert(MO.isImm() && "Not a valid bf_inv_mask_imm value!");
   O << "#" << lsb << ", #" << width;
 }