[CodeGen] Emit necessary .note sections for -fsplit-stack

Summary:
According to https://gcc.gnu.org/wiki/SplitStacks, the linker expects a zero-sized .note.GNU-split-stack section if split-stack is used (and also .note.GNU-no-split-stack section if it also contains non-split-stack functions), so it can handle the cases where a split-stack function calls non-split-stack function.

This change adds the sections if needed.

Fixes PR #34670.

Reviewers: thanm, rnk, luqmana

Reviewed By: rnk

Subscribers: llvm-commits

Patch by Cherry Zhang <cherryyz@google.com>

Differential Revision: https://reviews.llvm.org/D38051

llvm-svn: 314335

1 files changed, 26 insertions, 0 deletions

diff --git a/llvm/include/llvm/CodeGen/MachineModuleInfo.h b/llvm/include/llvm/CodeGen/MachineModuleInfo.h
index d64941a9e72..7b57a407b4b 100644
--- a/llvm/include/llvm/CodeGen/MachineModuleInfo.h
+++ b/llvm/include/llvm/CodeGen/MachineModuleInfo.h
@@ -125,6 +125,16 @@ class MachineModuleInfo : public ImmutablePass {
   /// comments in lib/Target/X86/X86FrameLowering.cpp for more details.
   bool UsesMorestackAddr;
 
+  /// True if the module contains split-stack functions. This is used to
+  /// emit .note.GNU-split-stack section as required by the linker for
+  /// special handling split-stack function calling no-split-stack function.
+  bool HasSplitStack;
+
+  /// True if the module contains no-split-stack functions. This is used to
+  /// emit .note.GNU-no-split-stack section when it also contains split-stack
+  /// functions.
+  bool HasNosplitStack;
+
   /// Maps IR Functions to their corresponding MachineFunctions.
   DenseMap<const Function*, std::unique_ptr<MachineFunction>> MachineFunctions;
   /// Next unique number available for a MachineFunction.
@@ -194,6 +204,22 @@ public:
     UsesMorestackAddr = b;
   }
 
+  bool hasSplitStack() const {
+    return HasSplitStack;
+  }
+
+  void setHasSplitStack(bool b) {
+    HasSplitStack = b;
+  }
+
+  bool hasNosplitStack() const {
+    return HasNosplitStack;
+  }
+
+  void setHasNosplitStack(bool b) {
+    HasNosplitStack = b;
+  }
+
   /// Return the symbol to be used for the specified basic block when its
   /// address is taken.  This cannot be its normal LBB label because the block
   /// may be accessed outside its containing function.