Use function attribute "stackrealign" to decide whether stack

realignment should be forced.

With this commit, we can now force stack realignment when doing LTO and
do so on a per-function basis. Also, add a new cl::opt option
"stackrealign" to CommandFlags.h which is used to force stack
realignment via llc's command line.

Out-of-tree projects currently using -force-align-stack to force stack
realignment should make changes to attach the attribute to the functions
in the IR.

Differential Revision: http://reviews.llvm.org/D11814

llvm-svn: 247450

1 files changed, 1 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/TargetRegisterInfo.cpp b/llvm/lib/CodeGen/TargetRegisterInfo.cpp
index 12e9e8cf1b6..2532eaf2ca0 100644
--- a/llvm/lib/CodeGen/TargetRegisterInfo.cpp
+++ b/llvm/lib/CodeGen/TargetRegisterInfo.cpp
@@ -24,14 +24,6 @@
 
 #define DEBUG_TYPE "target-reg-info"
 
-namespace llvm {
-cl::opt<bool>
-    ForceStackAlign("force-align-stack",
-                    cl::desc("Force align the stack to the minimum alignment"
-                             " needed for the function."),
-                    cl::init(false), cl::Hidden);
-} // end namespace llvm
-
 using namespace llvm;
 
 TargetRegisterInfo::TargetRegisterInfo(const TargetRegisterInfoDesc *ID,
@@ -321,7 +313,7 @@ bool TargetRegisterInfo::needsStackRealignment(
   unsigned StackAlign = TFI->getStackAlignment();
   bool requiresRealignment = ((MFI->getMaxAlignment() > StackAlign) ||
                               F->hasFnAttribute(Attribute::StackAlignment));
-  if (ForceStackAlign || requiresRealignment) {
+  if (MF.getFunction()->hasFnAttribute("stackrealign") || requiresRealignment) {
     if (canRealignStack(MF))
       return true;
     DEBUG(dbgs() << "Can't realign function's stack: " << F->getName() << "\n");