commit 46e38f36785508dc6f90e642c68e4a72a493e8f5
author Benjamin Kramer <benny.kra@googlemail.com> Wed Jun 08 10:01:20 2016 +0000
committer Benjamin Kramer <benny.kra@googlemail.com> Wed Jun 08 10:01:20 2016 +0000
tree 290f0903a81451736d6c920ef4b50bba0e995325
parent acadc8e0d64e90cded8f63a154ab3111a1d294f9

Avoid copies of std::strings and APInt/APFloats where we only read from it

As suggested by clang-tidy's performance-unnecessary-copy-initialization.
This can easily hit lifetime issues, so I audited every change and ran the
tests under asan, which came back clean.

llvm-svn: 272126

llvm/lib/Analysis/DependenceAnalysis.cpp

diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index 06eece2..3342bdf 100644
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -523,7 +523,7 @@
       }
       if (const SCEVConstant *CUB =
           collectConstantUpperBound(X->getAssociatedLoop(), Prod1->getType())) {
-        APInt UpperBound = CUB->getAPInt();
+        const APInt &UpperBound = CUB->getAPInt();
         DEBUG(dbgs() << "\t\tupper bound = " << UpperBound << "\n");
         if (Xq.sgt(UpperBound) || Yq.sgt(UpperBound)) {
           X->setEmpty();
@@ -1587,8 +1587,8 @@
 static
 bool isRemainderZero(const SCEVConstant *Dividend,
                      const SCEVConstant *Divisor) {
-  APInt ConstDividend = Dividend->getAPInt();
-  APInt ConstDivisor = Divisor->getAPInt();
+  const APInt &ConstDividend = Dividend->getAPInt();
+  const APInt &ConstDivisor = Divisor->getAPInt();
   return ConstDividend.srem(ConstDivisor) == 0;
 }
 

llvm/lib/Analysis/InstructionSimplify.cpp

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index b9f9d90a..43dcaec 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2300,7 +2300,7 @@
     } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
       APInt IntMin = APInt::getSignedMinValue(Width);
       APInt IntMax = APInt::getSignedMaxValue(Width);
-      APInt Val = CI2->getValue();
+      const APInt &Val = CI2->getValue();
       if (Val.isAllOnesValue()) {
         // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX]
         //    where CI2 != -1 and CI2 != 0 and CI2 != 1

llvm/lib/Analysis/ValueTracking.cpp

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index c7f6621..d735448 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1120,7 +1120,7 @@
     break;
   case Instruction::URem: {
     if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
-      APInt RA = Rem->getValue();
+      const APInt &RA = Rem->getValue();
       if (RA.isPowerOf2()) {
         APInt LowBits = (RA - 1);
         computeKnownBits(I->getOperand(0), KnownZero, KnownOne, Depth + 1, Q);