From 55c6d57734cd2f141dc2d6912fc22746d5eeae54 Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Sun, 1 Jan 2012 17:55:30 +0000
Subject: [PATCH] PatternMatch: Introduce a matcher for instructions with the
 "exact" bit. Use it to simplify a few matchers.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147403 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Support/PatternMatch.h  | 20 ++++++++++++++++++++
 lib/Analysis/InstructionSimplify.cpp | 15 +++++----------
 lib/Analysis/ValueTracking.cpp       | 14 +++++---------
 3 files changed, 30 insertions(+), 19 deletions(-)

diff --git a/include/llvm/Support/PatternMatch.h b/include/llvm/Support/PatternMatch.h
index 2dfbb182f94..d68c265e9d3 100644
--- a/include/llvm/Support/PatternMatch.h
+++ b/include/llvm/Support/PatternMatch.h
@@ -441,6 +441,26 @@ m_IDiv(const LHS &L, const RHS &R) {
   return BinOp2_match<LHS, RHS, Instruction::SDiv, Instruction::UDiv>(L, R);
 }
 
+//===----------------------------------------------------------------------===//
+// Class that matches exact binary ops.
+//
+template<typename SubPattern_t>
+struct Exact_match {
+  SubPattern_t SubPattern;
+
+  Exact_match(const SubPattern_t &SP) : SubPattern(SP) {}
+
+  template<typename OpTy>
+  bool match(OpTy *V) {
+    if (PossiblyExactOperator *PEO = dyn_cast<PossiblyExactOperator>(V))
+      return PEO->isExact() && SubPattern.match(V);
+    return false;
+  }
+};
+
+template<typename T>
+inline Exact_match<T> m_Exact(const T &SubPattern) { return SubPattern; }
+
 //===----------------------------------------------------------------------===//
 // Matchers for CmpInst classes
 //
diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index f1cfd6ceadd..6605586654c 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -812,14 +812,10 @@ static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
     return Op0;
 
   // (X / Y) * Y -> X if the division is exact.
-  Value *X = 0, *Y = 0;
-  if ((match(Op0, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op1) || // (X / Y) * Y
-      (match(Op1, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op0)) { // Y * (X / Y)
-    PossiblyExactOperator *Div =
-      cast<PossiblyExactOperator>(Y == Op1 ? Op0 : Op1);
-    if (Div->isExact())
-      return X;
-  }
+  Value *X = 0;
+  if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
+      match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0)))))   // Y * (X / Y)
+    return X;
 
   // i1 mul -> and.
   if (MaxRecurse && Op0->getType()->isIntegerTy(1))
@@ -1162,8 +1158,7 @@ static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
 
   // (X >> A) << A -> X
   Value *X;
-  if (match(Op0, m_Shr(m_Value(X), m_Specific(Op1))) &&
-      cast<PossiblyExactOperator>(Op0)->isExact())
+  if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
     return X;
   return 0;
 }
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index b9a48eaf571..6de4426ab82 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -811,11 +811,9 @@ bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, bool OrZero,
   // An exact divide or right shift can only shift off zero bits, so the result
   // is a power of two only if the first operand is a power of two and not
   // copying a sign bit (sdiv int_min, 2).
-  if (match(V, m_LShr(m_Value(), m_Value())) ||
-      match(V, m_UDiv(m_Value(), m_Value()))) {
-    PossiblyExactOperator *PEO = cast<PossiblyExactOperator>(V);
-    if (PEO->isExact())
-      return isPowerOfTwo(PEO->getOperand(0), TD, OrZero, Depth);
+  if (match(V, m_Exact(m_LShr(m_Value(), m_Value()))) ||
+      match(V, m_Exact(m_UDiv(m_Value(), m_Value())))) {
+    return isPowerOfTwo(cast<Operator>(V)->getOperand(0), TD, OrZero, Depth);
   }
 
   return false;
@@ -879,10 +877,8 @@ bool llvm::isKnownNonZero(Value *V, const TargetData *TD, unsigned Depth) {
       return true;
   }
   // div exact can only produce a zero if the dividend is zero.
-  else if (match(V, m_IDiv(m_Value(X), m_Value()))) {
-    PossiblyExactOperator *BO = cast<PossiblyExactOperator>(V);
-    if (BO->isExact())
-      return isKnownNonZero(X, TD, Depth);
+  else if (match(V, m_Exact(m_IDiv(m_Value(X), m_Value())))) {
+    return isKnownNonZero(X, TD, Depth);
   }
   // X + Y.
   else if (match(V, m_Add(m_Value(X), m_Value(Y)))) {