Faster stack-protector for Android/AArch64.

Bionic has a defined thread-local location for the stack protector
cookie. Emit a direct load instead of going through __stack_chk_guard.

llvm-svn: 265481

2 files changed, 10 insertions, 11 deletions

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index ea5518ed4c6..f81a3082ed2 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -2193,16 +2193,17 @@ unsigned X86TargetLowering::getAddressSpace() const {
   return 256;
 }
 
-bool X86TargetLowering::getStackCookieLocation(unsigned &AddressSpace,
-                                               unsigned &Offset) const {
+Value *X86TargetLowering::getStackCookieLocation(IRBuilder<> &IRB) const {
   if (!Subtarget.isTargetLinux())
-    return false;
+    return TargetLowering::getStackCookieLocation(IRB);
 
   // %fs:0x28, unless we're using a Kernel code model, in which case it's %gs:
   // %gs:0x14 on i386
-  Offset = (Subtarget.is64Bit()) ? 0x28 : 0x14;
-  AddressSpace = getAddressSpace();
-  return true;
+  unsigned Offset = (Subtarget.is64Bit()) ? 0x28 : 0x14;
+  unsigned AddressSpace = getAddressSpace();
+  return ConstantExpr::getIntToPtr(
+      ConstantInt::get(Type::getInt32Ty(IRB.getContext()), Offset),
+      Type::getInt8PtrTy(IRB.getContext())->getPointerTo(AddressSpace));
 }
 
 Value *X86TargetLowering::getSafeStackPointerLocation(IRBuilder<> &IRB) const {
diff --git a/llvm/lib/Target/X86/X86ISelLowering.h b/llvm/lib/Target/X86/X86ISelLowering.h
index 664eadd000a..7007782ccf4 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.h
+++ b/llvm/lib/Target/X86/X86ISelLowering.h
@@ -960,11 +960,9 @@ namespace llvm {
     FastISel *createFastISel(FunctionLoweringInfo &funcInfo,
                              const TargetLibraryInfo *libInfo) const override;
 
-    /// Return true if the target stores stack protector cookies at a fixed
-    /// offset in some non-standard address space, and populates the address
-    /// space and offset as appropriate.
-    bool getStackCookieLocation(unsigned &AddressSpace,
-                                unsigned &Offset) const override;
+    /// If the target has a standard location for the stack protector cookie,
+    /// returns the address of that location. Otherwise, returns nullptr.
+    Value *getStackCookieLocation(IRBuilder<> &IRB) 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