3 files changed, 32 insertions, 0 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index fbead736ec0..d366e280739 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -2079,6 +2079,29 @@ bool X86TargetLowering::getStackCookieLocation(unsigned &AddressSpace,
   return true;
 }
 
+/// Android provides a fixed TLS slot for the SafeStack pointer.
+/// See the definition of TLS_SLOT_SAFESTACK in
+/// https://android.googlesource.com/platform/bionic/+/master/libc/private/bionic_tls.h
+bool X86TargetLowering::getSafeStackPointerLocation(unsigned &AddressSpace,
+                                                    unsigned &Offset) const {
+  if (!Subtarget->isTargetAndroid())
+    return false;
+
+  if (Subtarget->is64Bit()) {
+    // %fs:0x48, unless we're using a Kernel code model, in which case it's %gs:
+    Offset = 0x48;
+    if (getTargetMachine().getCodeModel() == CodeModel::Kernel)
+      AddressSpace = 256;
+    else
+      AddressSpace = 257;
+  } else {
+    // %gs:0x24 on i386
+    Offset = 0x24;
+    AddressSpace = 256;
+  }
+  return true;
+}
+
 bool X86TargetLowering::isNoopAddrSpaceCast(unsigned SrcAS,
                                             unsigned DestAS) const {
   assert(SrcAS != DestAS && "Expected different address spaces!");
diff --git a/llvm/lib/Target/X86/X86ISelLowering.h b/llvm/lib/Target/X86/X86ISelLowering.h
index 949c6511bde..ff680a52b1a 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.h
+++ b/llvm/lib/Target/X86/X86ISelLowering.h
@@ -891,6 +891,12 @@ namespace llvm {
     bool getStackCookieLocation(unsigned &AddressSpace,
                                 unsigned &Offset) const override;
 
+    /// Return true if the target stores SafeStack pointer at a fixed offset in
+    /// some non-standard address space, and populates the address space and
+    /// offset as appropriate.
+    bool getSafeStackPointerLocation(unsigned &AddressSpace,
+                                     unsigned &Offset) const override;
+
     SDValue BuildFILD(SDValue Op, EVT SrcVT, SDValue Chain, SDValue StackSlot,
                       SelectionDAG &DAG) const;
 
diff --git a/llvm/lib/Target/X86/X86Subtarget.h b/llvm/lib/Target/X86/X86Subtarget.h
index c5d74e66b7b..52e68c08180 100644
--- a/llvm/lib/Target/X86/X86Subtarget.h
+++ b/llvm/lib/Target/X86/X86Subtarget.h
@@ -394,6 +394,9 @@ public:
   bool isTargetMachO() const { return TargetTriple.isOSBinFormatMachO(); }
 
   bool isTargetLinux() const { return TargetTriple.isOSLinux(); }
+  bool isTargetAndroid() const {
+    return TargetTriple.getEnvironment() == Triple::Android;
+  }
   bool isTargetNaCl() const { return TargetTriple.isOSNaCl(); }
   bool isTargetNaCl32() const { return isTargetNaCl() && !is64Bit(); }
   bool isTargetNaCl64() const { return isTargetNaCl() && is64Bit(); }