DebugInfo: Support for compressed debug info sections

1) When creating a .debug_* section and instead create a .zdebug_
   section.
2) When creating a fragment in a .zdebug_* section, make it a compressed
   fragment.
3) When computing the size of a compressed section, compress the data
   and use the size of the compressed data.
4) Emit the compressed bytes.

Also, check that only if a section has a compressed fragment, then that
is the only fragment in the section.

Assert-fail if the fragment's data is modified after it is compressed.

Initial review on llvm-commits by Eric Christopher and Rafael Espindola.

llvm-svn: 204958

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCAsmInfo.cpp b/llvm/lib/MC/MCAsmInfo.cpp
index f09bbd1a660..c78d3d574a4 100644
--- a/llvm/lib/MC/MCAsmInfo.cpp
+++ b/llvm/lib/MC/MCAsmInfo.cpp
@@ -100,6 +100,8 @@ MCAsmInfo::MCAsmInfo() {
   //   architecture basis.
   //   - The target subclasses for AArch64, ARM, and X86  handle these cases
   UseIntegratedAssembler = false;
+
+  CompressDebugSections = false;
 }
 
 MCAsmInfo::~MCAsmInfo() {