[XCOFF][AIX] Alternative path in EHStreamer for platforms do not have uleb128 support

Summary:
Not all system assembler supports `.uleb128 label2 - label1` form.
When the target do not support this form, we have to take
alternative manual calculation to get the offsets from them.

Reviewed By: hubert.reinterpretcast

Diffierential Revision: https://reviews.llvm.org/D92058

1 files changed, 10 insertions, 0 deletions

diff --git a/llvm/lib/Target/TargetLoweringObjectFile.cpp b/llvm/lib/Target/TargetLoweringObjectFile.cpp
index eea0aee..087d5e3 100644
--- a/llvm/lib/Target/TargetLoweringObjectFile.cpp
+++ b/llvm/lib/Target/TargetLoweringObjectFile.cpp
@@ -20,6 +20,7 @@
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Mangler.h"
 #include "llvm/IR/Module.h"
+#include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCStreamer.h"
@@ -55,6 +56,15 @@ TargetLoweringObjectFile::~TargetLoweringObjectFile() {
   delete Mang;
 }
 
+unsigned TargetLoweringObjectFile::getCallSiteEncoding() const {
+  // If target does not have LEB128 directives, we would need the
+  // call site encoding to be udata4 so that the alternative path
+  // for not having LEB128 directives could work.
+  if (!getContext().getAsmInfo()->hasLEB128Directives())
+    return dwarf::DW_EH_PE_udata4;
+  return CallSiteEncoding;
+}
+
 static bool isNullOrUndef(const Constant *C) {
   // Check that the constant isn't all zeros or undefs.
   if (C->isNullValue() || isa<UndefValue>(C))