[llvm] r298236 - [ConstantRange] Add setSizeSmallerThanOf method.

[Michael Zolotukhin via llvm-commits]

Author: mzolotukhin
Date: Mon Mar 20 01:33:07 2017
New Revision: 298236

URL: http://llvm.org/viewvc/llvm-project?rev=298236&view=rev
Log:
[ConstantRange] Add setSizeSmallerThanOf method.

Summary:
ConstantRange class currently has a method getSetSize, which is mostly used to
compare set sizes of two constant ranges (there is only one spot where it's used
in a slightly different scenario). This patch introduces setSizeSmallerThanOf
method, which does such comparison in a more efficient way. In the original
method we have to extend our types to (BitWidth+1), which can result it using
slow case of APInt, extra memory allocations, etc.

The change is supposed to not change any functionality, but it slightly improves
compile time. Here is compile time improvements that I observed on CTMark:
* tramp3d-v4	-2.02%
* pairlocalalign	-1.82%
* lencod	-1.67%

Reviewers: sanjoy, atrick, pete

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D31104

Modified:
    llvm/trunk/include/llvm/IR/ConstantRange.h
    llvm/trunk/lib/IR/ConstantRange.cpp

Modified: llvm/trunk/include/llvm/IR/ConstantRange.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/ConstantRange.h?rev=298236&r1=298235&r2=298236&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/ConstantRange.h (original)
+++ llvm/trunk/include/llvm/IR/ConstantRange.h Mon Mar 20 01:33:07 2017
@@ -184,6 +184,10 @@ public:
   ///
   APInt getSetSize() const;
 
+  /// Compare set size of this range with the range CR.
+  ///
+  bool isSizeStrictlySmallerThanOf(const ConstantRange &CR) const;
+
   /// Return the largest unsigned value contained in the ConstantRange.
   ///
   APInt getUnsignedMax() const;

Modified: llvm/trunk/lib/IR/ConstantRange.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/ConstantRange.cpp?rev=298236&r1=298235&r2=298236&view=diff
==============================================================================
--- llvm/trunk/lib/IR/ConstantRange.cpp (original)
+++ llvm/trunk/lib/IR/ConstantRange.cpp Mon Mar 20 01:33:07 2017
@@ -272,6 +272,22 @@ APInt ConstantRange::getSetSize() const
   return (Upper - Lower).zext(getBitWidth()+1);
 }
 
+/// isSizeStrictlySmallerThanOf - Compare set size of this range with the range
+/// CR.
+/// This function is faster than comparing results of getSetSize for the two
+/// ranges, because we don't need to extend bitwidth of APInts we're operating
+/// with.
+///
+bool
+ConstantRange::isSizeStrictlySmallerThanOf(const ConstantRange &Other) const {
+  assert(getBitWidth() == Other.getBitWidth());
+  if (isFullSet())
+    return false;
+  if (Other.isFullSet())
+    return true;
+  return (Upper - Lower).ult(Other.Upper - Other.Lower);
+}
+
 /// getUnsignedMax - Return the largest unsigned value contained in the
 /// ConstantRange.
 ///
@@ -414,7 +430,7 @@ ConstantRange ConstantRange::intersectWi
       if (CR.Upper.ule(Lower))
         return ConstantRange(CR.Lower, Upper);
 
-      if (getSetSize().ult(CR.getSetSize()))
+      if (isSizeStrictlySmallerThanOf(CR))
         return *this;
       return CR;
     }
@@ -429,7 +445,7 @@ ConstantRange ConstantRange::intersectWi
 
   if (CR.Upper.ult(Upper)) {
     if (CR.Lower.ult(Upper)) {
-      if (getSetSize().ult(CR.getSetSize()))
+      if (isSizeStrictlySmallerThanOf(CR))
         return *this;
       return CR;
     }
@@ -445,7 +461,7 @@ ConstantRange ConstantRange::intersectWi
 
     return ConstantRange(CR.Lower, Upper);
   }
-  if (getSetSize().ult(CR.getSetSize()))
+  if (isSizeStrictlySmallerThanOf(CR))
     return *this;
   return CR;
 }
@@ -739,17 +755,16 @@ ConstantRange::add(const ConstantRange &
   if (isFullSet() || Other.isFullSet())
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 
-  APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
   APInt NewLower = getLower() + Other.getLower();
   APInt NewUpper = getUpper() + Other.getUpper() - 1;
   if (NewLower == NewUpper)
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 
   ConstantRange X = ConstantRange(NewLower, NewUpper);
-  if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
+  if (X.isSizeStrictlySmallerThanOf(*this) ||
+      X.isSizeStrictlySmallerThanOf(Other))
     // We've wrapped, therefore, full set.
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
-
   return X;
 }
 
@@ -773,17 +788,16 @@ ConstantRange::sub(const ConstantRange &
   if (isFullSet() || Other.isFullSet())
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 
-  APInt Spread_X = getSetSize(), Spread_Y = Other.getSetSize();
   APInt NewLower = getLower() - Other.getUpper() + 1;
   APInt NewUpper = getUpper() - Other.getLower();
   if (NewLower == NewUpper)
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
 
   ConstantRange X = ConstantRange(NewLower, NewUpper);
-  if (X.getSetSize().ult(Spread_X) || X.getSetSize().ult(Spread_Y))
+  if (X.isSizeStrictlySmallerThanOf(*this) ||
+      X.isSizeStrictlySmallerThanOf(Other))
     // We've wrapped, therefore, full set.
     return ConstantRange(getBitWidth(), /*isFullSet=*/true);
-
   return X;
 }
 
@@ -837,7 +851,7 @@ ConstantRange::multiply(const ConstantRa
   ConstantRange Result_sext(std::min(L, Compare), std::max(L, Compare) + 1);
   ConstantRange SR = Result_sext.truncate(getBitWidth());
 
-  return UR.getSetSize().ult(SR.getSetSize()) ? UR : SR;
+  return UR.isSizeStrictlySmallerThanOf(SR) ? UR : SR;
 }
 
 ConstantRange