[PATCH] D39214: [MachineModuleInfoImpls] Replace qsort with std::stable_sort

[Mandeep Singh Grang via Phabricator via llvm-commits]

mgrang created this revision.

This seems to be the only place in llvm we directly call qsort. We can replace
this with a call to std::stable_sort. Also minor cleanup of the sorting function.

Note: We need std::stable_sort as using std::sort causes a couple of tests to fail. 
This would have been the case with qsort too as both are unstable.
It's just that we may be getting lucky.


Repository:
  rL LLVM

https://reviews.llvm.org/D39214

Files:
  lib/CodeGen/MachineModuleInfoImpls.cpp


Index: lib/CodeGen/MachineModuleInfoImpls.cpp
===================================================================
--- lib/CodeGen/MachineModuleInfoImpls.cpp
+++ lib/CodeGen/MachineModuleInfoImpls.cpp
@@ -15,8 +15,6 @@
 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/MC/MCSymbol.h"
-#include <cstdlib>
-#include <utility>
 
 using namespace llvm;
 
@@ -28,20 +26,17 @@
 void MachineModuleInfoMachO::anchor() {}
 void MachineModuleInfoELF::anchor() {}
 
-static int SortSymbolPair(const void *LHS, const void *RHS) {
-  using PairTy = std::pair<MCSymbol *, MachineModuleInfoImpl::StubValueTy>;
-
-  const MCSymbol *LHSS = ((const PairTy *)LHS)->first;
-  const MCSymbol *RHSS = ((const PairTy *)RHS)->first;
-  return LHSS->getName().compare(RHSS->getName());
+using PairTy = std::pair<MCSymbol *, MachineModuleInfoImpl::StubValueTy>;
+static int SortSymbolPair(PairTy LHS, PairTy RHS) {
+  return LHS.first->getName().compare(RHS.first->getName());
 }
 
 MachineModuleInfoImpl::SymbolListTy MachineModuleInfoImpl::getSortedStubs(
     DenseMap<MCSymbol *, MachineModuleInfoImpl::StubValueTy> &Map) {
   MachineModuleInfoImpl::SymbolListTy List(Map.begin(), Map.end());
 
   if (!List.empty())
-    qsort(&List[0], List.size(), sizeof(List[0]), SortSymbolPair);
+    std::stable_sort(List.begin(), List.end(), SortSymbolPair);
 
   Map.clear();
   return List;


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