On ELF, put PIC jump tables in a non executable section.

Fixes PR22558.

llvm-svn: 228939

1 files changed, 18 insertions, 0 deletions

diff --git a/llvm/lib/Target/TargetLoweringObjectFile.cpp b/llvm/lib/Target/TargetLoweringObjectFile.cpp
index c098035a5aa..faa6fbe6075 100644
--- a/llvm/lib/Target/TargetLoweringObjectFile.cpp
+++ b/llvm/lib/Target/TargetLoweringObjectFile.cpp
@@ -275,6 +275,24 @@ const MCSection *TargetLoweringObjectFile::getSectionForJumpTable(
   return getSectionForConstant(SectionKind::getReadOnly(), /*C=*/nullptr);
 }
 
+bool TargetLoweringObjectFile::shouldPutJumpTableInFunctionSection(
+    bool UsesLabelDifference, const Function &F) const {
+  // In PIC mode, we need to emit the jump table to the same section as the
+  // function body itself, otherwise the label differences won't make sense.
+  // FIXME: Need a better predicate for this: what about custom entries?
+  if (UsesLabelDifference)
+    return true;
+
+  // We should also do if the section name is NULL or function is declared
+  // in discardable section
+  // FIXME: this isn't the right predicate, should be based on the MCSection
+  // for the function.
+  if (F.isWeakForLinker())
+    return true;
+
+  return false;
+}
+
 /// getSectionForConstant - Given a mergable constant with the
 /// specified size and relocation information, return a section that it
 /// should be placed in.