Fix differences in codegen between Linux and Windows toolchains

Summary:
    There are differences in codegen between Linux and Windows due to:
    1. Using std::sort which uses quicksort which is a non-stable sort.

    2. Iterating over Set data structure where the iteration order is
       non deterministic.

Reviewers: arsenm, grosbach, junbuml, zinob, MatzeB

Subscribers: MatzeB, wdng

Differential Revision: https://reviews.llvm.org/D25695

llvm-svn: 284441

1 files changed, 5 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp b/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp
index 6cb59a6..b86406e 100644
--- a/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp
+++ b/llvm/lib/CodeGen/LocalStackSlotAllocation.cpp
@@ -55,7 +55,8 @@ namespace {
     FrameRef(MachineBasicBlock::iterator I, int64_t Offset, int Idx) :
       MI(I), LocalOffset(Offset), FrameIdx(Idx) {}
     bool operator<(const FrameRef &RHS) const {
-      return LocalOffset < RHS.LocalOffset;
+      return std::tie(LocalOffset, FrameIdx) <
+             std::tie(RHS.LocalOffset, RHS.FrameIdx);
     }
     MachineBasicBlock::iterator getMachineInstr() const { return MI; }
     int64_t getLocalOffset() const { return LocalOffset; }
@@ -318,8 +319,9 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
     }
   }
 
-  // Sort the frame references by local offset
-  array_pod_sort(FrameReferenceInsns.begin(), FrameReferenceInsns.end());
+  // Sort the frame references by local offset.
+  // Use frame index as a tie-breaker in case MI's have the same offset.
+  std::sort(FrameReferenceInsns.begin(), FrameReferenceInsns.end());
 
   MachineBasicBlock *Entry = &Fn.front();