Add AsmPrinter support for emitting a directive to declare that

the code being generated does not require an executable stack.

Also, add target-specific code to make use of this on Linux
on x86. 

llvm-svn: 50634

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter.cpp
index 65b8c436f78..9c4e789251a 100644
--- a/llvm/lib/CodeGen/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter.cpp
@@ -192,6 +192,13 @@ bool AsmPrinter::doFinalization(Module &M) {
                                          E = CMM->begin(); I != E; )
     (*--I)->finishAssembly(O, *this, *TAI);
 
+  // If we don't have any trampolines, then we don't require stack memory
+  // to be executable. Some targets have a directive to declare this.
+  Function* InitTrampolineIntrinsic = M.getFunction("llvm.init.trampoline");
+  if (!InitTrampolineIntrinsic || InitTrampolineIntrinsic->use_empty())
+    if (TAI->getNonexecutableStackDirective())
+      O << TAI->getNonexecutableStackDirective() << "\n";
+
   delete Mang; Mang = 0;
   return false;
 }