ARM: support stack probe size on Windows on ARM

Now that -mstack-probe-size is piped through to the backend via the function
attribute as on Windows x86, honour the value to permit handling of non-default
values for stack probes.  This is needed /Gs with the clang-cl driver or
-mstack-probe-size with the clang driver when targeting Windows on ARM.

llvm-svn: 227667

1 files changed, 7 insertions, 3 deletions

diff --git a/llvm/lib/Target/ARM/ARMFrameLowering.cpp b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
index 784755e1300..271973048ae 100644
--- a/llvm/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
@@ -164,9 +164,13 @@ static int sizeOfSPAdjustment(const MachineInstr *MI) {
 static bool WindowsRequiresStackProbe(const MachineFunction &MF,
                                       size_t StackSizeInBytes) {
   const MachineFrameInfo *MFI = MF.getFrameInfo();
-  if (MFI->getStackProtectorIndex() > 0)
-    return StackSizeInBytes >= 4080;
-  return StackSizeInBytes >= 4096;
+  const Function *F = MF.getFunction();
+  unsigned StackProbeSize = (MFI->getStackProtectorIndex() > 0) ? 4080 : 4096;
+  if (F->hasFnAttribute("stack-probe-size"))
+    F->getFnAttribute("stack-probe-size")
+        .getValueAsString()
+        .getAsInteger(0, StackProbeSize);
+  return StackSizeInBytes >= StackProbeSize;
 }
 
 namespace {