[JITLink] Tighten section sorting criteria to fix a flaky test case.

Sections may have zero size and zero-sized sections may share a start address
with other zero-sized sections. For the section overlap test to function
correctly zero-sized sections must be ordered before any non-zero sized ones.

This should fix the intermittent failures in the
test/ExecutionEngine/JITLink/X86/MachO_zero_fill_alignment.s test case that
have been observed on some builders.

1 files changed, 3 insertions, 1 deletions

diff --git a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
index 7366f53ebf3..c1dc138ee70 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
@@ -179,7 +179,9 @@ Error MachOLinkGraphBuilder::createNormalizedSections() {
   llvm::sort(Sections,
              [](const NormalizedSection *LHS, const NormalizedSection *RHS) {
                assert(LHS && RHS && "Null section?");
-               return LHS->Address < RHS->Address;
+               if (LHS->Address != RHS->Address)
+                 return LHS->Address < RHS->Address;
+               return LHS->Size < RHS->Size;
              });
 
   for (unsigned I = 0, E = Sections.size() - 1; I != E; ++I) {