Use separate random number generator for each randomization pass

src/IceELFObjectWriter.cpp

 //===- subzero/src/IceELFObjectWriter.cpp - ELF object file writer --------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 494 matching lines @@
       SecStrBuf.str(), SHT_PROGBITS, ShFlags, Align, WriteAmt);
   RODataSections.push_back(Section);
   SizeT OffsetInSection = 0;
   // The symbol table entry doesn't need to know the defined symbol's
   // size since this is in a section with a fixed Entry Size.
   const SizeT SymbolSize = 0;
   Section->setFileOffset(alignFileOffset(Align));
 
   // If the -reorder-pooled-constant option is set to true, we should shuffle
   // the constants before we emit them.
-  auto *CtxPtr = &Ctx;
-  if (Ctx.getFlags().shouldReorderPooledConstants())
-    RandomShuffle(Pool.begin(), Pool.end(), [CtxPtr](uint64_t N) {
-      return (uint32_t)CtxPtr->getRNG().next(N);
-    });
+  if (Ctx.getFlags().shouldReorderPooledConstants()) {
+    if (!Pool.empty()) {

[Jim Stichnoth, 2015/08/19 19:03:04]

Can combine this and the above condition, as noted in another comment.

[qining, 2015/08/19 23:25:48]

Done.

+      // Use the constant's kind value as the salt for creating random number
+      // generator.
+      Operand::OperandKind K = (*Pool.begin())->getKind();
+      RandomNumberGenerator RNG(Ctx.getFlags().getRandomSeed(),
+                                RS_PooledConstantReordering, K);
+      RandomShuffle(Pool.begin(), Pool.end(),
+                    [&RNG](uint64_t N) { return (uint32_t)RNG.next(N); });
+    }
+  }
   // Write the data.
   for (Constant *C : Pool) {
     if (!C->getShouldBePooled())
       continue;
     auto Const = llvm::cast<ConstType>(C);
     std::string SymBuffer;
     llvm::raw_string_ostream SymStrBuf(SymBuffer);
     Const->emitPoolLabel(SymStrBuf);
     std::string &SymName = SymStrBuf.str();
     SymTab->createDefinedSym(SymName, STT_NOTYPE, STB_LOCAL, Section,
@@ skipping 135 matching lines @@
   if (ELF64) {
     writeELFHeaderInternal<true>(ShOffset, ShStrTab->getNumber(),
                                  AllSections.size());
   } else {
     writeELFHeaderInternal<false>(ShOffset, ShStrTab->getNumber(),
                                   AllSections.size());
   }
 }
 
 } // end of namespace Ice