From fb8a66fbc558e3dc1f52e5fa4aac3d9ed1fef5ae Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Sat, 31 Jan 2015 02:26:37 +0000
Subject: [PATCH] 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
---
 llvm/lib/Target/ARM/ARMFrameLowering.cpp      | 10 ++++---
 .../ARM/Windows/stack-probe-non-default.ll    | 27 +++++++++++++++++++
 2 files changed, 34 insertions(+), 3 deletions(-)
 create mode 100644 llvm/test/CodeGen/ARM/Windows/stack-probe-non-default.ll

diff --git a/llvm/lib/Target/ARM/ARMFrameLowering.cpp b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
index 784755e13004..271973048ae9 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 {
diff --git a/llvm/test/CodeGen/ARM/Windows/stack-probe-non-default.ll b/llvm/test/CodeGen/ARM/Windows/stack-probe-non-default.ll
new file mode 100644
index 000000000000..796bcddd3ca5
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/Windows/stack-probe-non-default.ll
@@ -0,0 +1,27 @@
+; RUN: llc -mtriple thumbv7-windows -mcpu cortex-a9 -o - %s \
+; RUN:     | FileCheck %s -check-prefix CHECK-DEFAULT-CODE-MODEL
+
+; RUN: llc -mtriple thumbv7-windows -mcpu cortex-a9 -code-model large -o - %s \
+; RUN:     | FileCheck %s -check-prefix CHECK-LARGE-CODE-MODEL
+
+declare dllimport arm_aapcs_vfpcc void @initialise(i8*)
+
+define dllexport arm_aapcs_vfpcc signext i8 @function(i32 %offset) #0 {
+entry:
+  %buffer = alloca [4096 x i8], align 1
+  %0 = getelementptr inbounds [4096 x i8]* %buffer, i32 0, i32 0
+  call arm_aapcs_vfpcc void @initialise(i8* %0)
+  %arrayidx = getelementptr inbounds [4096 x i8]* %buffer, i32 0, i32 %offset
+  %1 = load i8* %arrayidx, align 1
+  ret i8 %1
+}
+
+attributes #0 = { "stack-probe-size"="8096" }
+
+; CHECK-DEFAULT-CODE-MODEL-NOT: __chkstk
+; CHECK-DEFAULT-CODE-MODEL: sub.w sp, sp, #4096
+
+; CHECK-LARGE-CODE-MODEL-NOT: movw r12, :lower16:__chkstk
+; CHECK-LARGE-CODE-MODEL-NOT: movt r12, :upper16:__chkstk
+; CHECK-LARGE-CODE-MODEL: sub.w sp, sp, #4096
+