[llvm-objdump] Use a counter for llvm-objdump -h instead of the section index.

Summary:
When listing the index in `llvm-objdump -h`, use a zero-based counter instead of the actual section index (e.g. shdr->sh_index for ELF).

While this is effectively a noop for now (except one unit test for XCOFF), the index values will change in a future patch that filters certain sections out (e.g. symbol tables). See D68669 for more context. Note: the test case in `test/tools/llvm-objdump/X86/section-index.s` already covers the case of incrementing the section index counter when sections are skipped.

Reviewers: grimar, jhenderson, espindola

Reviewed By: grimar

Subscribers: emaste, sbc100, arichardson, aheejin, arphaman, seiya, llvm-commits, MaskRay

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68848

llvm-svn: 374931

1 files changed, 13 insertions, 1 deletions

diff --git a/llvm/tools/llvm-objdump/llvm-objdump.h b/llvm/tools/llvm-objdump/llvm-objdump.h
index d36c4fd..43ce02a 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.h
+++ b/llvm/tools/llvm-objdump/llvm-objdump.h
@@ -31,6 +31,8 @@ extern cl::opt<bool> Demangle;
 
 typedef std::function<bool(llvm::object::SectionRef const &)> FilterPredicate;
 
+/// A filtered iterator for SectionRefs that skips sections based on some given
+/// predicate.
 class SectionFilterIterator {
 public:
   SectionFilterIterator(FilterPredicate P,
@@ -60,6 +62,8 @@ private:
   llvm::object::section_iterator End;
 };
 
+/// Creates an iterator range of SectionFilterIterators for a given Object and
+/// predicate.
 class SectionFilter {
 public:
   SectionFilter(FilterPredicate P, llvm::object::ObjectFile const &O)
@@ -79,7 +83,15 @@ private:
 };
 
 // Various helper functions.
-SectionFilter ToolSectionFilter(llvm::object::ObjectFile const &O);
+
+/// Creates a SectionFilter with a standard predicate that conditionally skips
+/// sections when the --section objdump flag is provided.
+///
+/// Idx is an optional output parameter that keeps track of which section index
+/// this is. This may be different than the actual section number, as some
+/// sections may be filtered (e.g. symbol tables).
+SectionFilter ToolSectionFilter(llvm::object::ObjectFile const &O,
+                                uint64_t *Idx = nullptr);
 
 Error getELFRelocationValueString(const object::ELFObjectFileBase *Obj,
                                   const object::RelocationRef &Rel,