on darwin empty functions need to codegen into something of non-zero length,

otherwise labels get incorrectly merged.  We handled this by emitting a 
".byte 0", but this isn't correct on thumb/arm targets where the text segment
needs to be a multiple of 2/4 bytes.  Handle this by emitting a noop.  This
is more gross than it should be because arm/ppc are not fully mc'ized yet.

This fixes rdar://7908505

llvm-svn: 102400

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 4ed7434e45a..9a41a4a525d 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -27,6 +27,7 @@
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/LiveVariables.h"
 #include "llvm/CodeGen/PseudoSourceValue.h"
+#include "llvm/MC/MCInst.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -3766,3 +3767,9 @@ void X86InstrInfo::SetSSEDomain(MachineInstr *MI, unsigned Domain) const {
   assert(table && "Cannot change domain");
   MI->setDesc(get(table[Domain-1]));
 }
+
+/// getNoopForMachoTarget - Return the noop instruction to use for a noop.
+void X86InstrInfo::getNoopForMachoTarget(MCInst &NopInst) const {
+  NopInst.setOpcode(X86::NOOP);
+}
+