[WebAssembly] Don't create a needless .note.GNU-stack section

WebAssembly's stack will never be executable by default, so it isn't
necessary to declare .note.GNU-stack sections to request a non-executable
stack.

Differential Revision: http://reviews.llvm.org/D15969

llvm-svn: 257962

2 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCAsmInfoELF.cpp b/llvm/lib/MC/MCAsmInfoELF.cpp
index 2bff6e05966..26e5608d873 100644
--- a/llvm/lib/MC/MCAsmInfoELF.cpp
+++ b/llvm/lib/MC/MCAsmInfoELF.cpp
@@ -21,6 +21,8 @@ using namespace llvm;
 void MCAsmInfoELF::anchor() { }
 
 MCSection *MCAsmInfoELF::getNonexecutableStackSection(MCContext &Ctx) const {
+  if (!UsesNonexecutableStackSection)
+    return nullptr;
   return Ctx.getELFSection(".note.GNU-stack", ELF::SHT_PROGBITS, 0);
 }
 
@@ -29,4 +31,5 @@ MCAsmInfoELF::MCAsmInfoELF() {
   WeakRefDirective = "\t.weak\t";
   PrivateGlobalPrefix = ".L";
   PrivateLabelPrefix = ".L";
+  UsesNonexecutableStackSection = true;
 }
diff --git a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCAsmInfo.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCAsmInfo.cpp
index 02c717a9210..84c77d22340 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCAsmInfo.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCAsmInfo.cpp
@@ -48,4 +48,7 @@ WebAssemblyMCAsmInfo::WebAssemblyMCAsmInfo(const Triple &T) {
   ExceptionsType = ExceptionHandling::None;
 
   // TODO: UseIntegratedAssembler?
+
+  // WebAssembly's stack is never executable.
+  UsesNonexecutableStackSection = false;
 }