[llvm] r298233 - [APInt] Don't initialize VAL to 0 in APInt constructors. Push it down to the initSlowCase and other init methods.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Sun Mar 19 20:29:52 2017
New Revision: 298233

URL: http://llvm.org/viewvc/llvm-project?rev=298233&view=rev
Log:
[APInt] Don't initialize VAL to 0 in APInt constructors. Push it down to the initSlowCase and other init methods.

I'm not sure if zeroing VAL before writing pVal is really necessary, but at least one other place did it in code.

But by taking the store out of line, this reduces the opt binary by about 20k on my local x86-64 build.

Modified:
    llvm/trunk/include/llvm/ADT/APInt.h
    llvm/trunk/lib/Support/APInt.cpp

Modified: llvm/trunk/include/llvm/ADT/APInt.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/APInt.h?rev=298233&r1=298232&r2=298233&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/APInt.h (original)
+++ llvm/trunk/include/llvm/ADT/APInt.h Sun Mar 19 20:29:52 2017
@@ -232,7 +232,7 @@ public:
   /// \param val the initial value of the APInt
   /// \param isSigned how to treat signedness of val
   APInt(unsigned numBits, uint64_t val, bool isSigned = false)
-      : BitWidth(numBits), VAL(0) {
+      : BitWidth(numBits) {
     assert(BitWidth && "bitwidth too small");
     if (isSingleWord()) {
       VAL = val;
@@ -275,7 +275,7 @@ public:
 
   /// Simply makes *this a copy of that.
   /// @brief Copy Constructor.
-  APInt(const APInt &that) : BitWidth(that.BitWidth), VAL(0) {
+  APInt(const APInt &that) : BitWidth(that.BitWidth) {
     if (isSingleWord())
       VAL = that.VAL;
     else

Modified: llvm/trunk/lib/Support/APInt.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/APInt.cpp?rev=298233&r1=298232&r2=298233&view=diff
==============================================================================
--- llvm/trunk/lib/Support/APInt.cpp (original)
+++ llvm/trunk/lib/Support/APInt.cpp Sun Mar 19 20:29:52 2017
@@ -76,6 +76,7 @@ inline static unsigned getDigit(char cdi
 
 
 void APInt::initSlowCase(uint64_t val, bool isSigned) {
+  VAL = 0;
   pVal = getClearedMemory(getNumWords());
   pVal[0] = val;
   if (isSigned && int64_t(val) < 0)
@@ -85,6 +86,7 @@ void APInt::initSlowCase(uint64_t val, b
 }
 
 void APInt::initSlowCase(const APInt& that) {
+  VAL = 0;
   pVal = getMemory(getNumWords());
   memcpy(pVal, that.pVal, getNumWords() * APINT_WORD_SIZE);
 }
@@ -96,6 +98,7 @@ void APInt::initFromArray(ArrayRef<uint6
     VAL = bigVal[0];
   else {
     // Get memory, cleared to 0
+    VAL = 0;
     pVal = getClearedMemory(getNumWords());
     // Calculate the number of words to copy
     unsigned words = std::min<unsigned>(bigVal.size(), getNumWords());
@@ -107,12 +110,12 @@ void APInt::initFromArray(ArrayRef<uint6
 }
 
 APInt::APInt(unsigned numBits, ArrayRef<uint64_t> bigVal)
-  : BitWidth(numBits), VAL(0) {
+  : BitWidth(numBits) {
   initFromArray(bigVal);
 }
 
 APInt::APInt(unsigned numBits, unsigned numWords, const uint64_t bigVal[])
-  : BitWidth(numBits), VAL(0) {
+  : BitWidth(numBits) {
   initFromArray(makeArrayRef(bigVal, numWords));
 }