set default max-page-size to 4KB in lld for Android Aarch64

Summary:
This patch passes an option '-z max-page-size=4096' to lld through clang driver.

This is for Android on Aarch64 target.

The lld default page size is too large for Aarch64, which produces larger .so files and images for arm64 device targets.
In this patch we set default page size to 4KB for Android Aarch64 targets instead.

Reviewers: srhines, danalbert, ruiu, chh, peter.smith

Reviewed By: srhines

Subscribers: javed.absar, kristof.beyls, cfe-commits, george.burgess.iv, llozano

Differential Revision: https://reviews.llvm.org/D55029

llvm-svn: 347897

clang/lib/Driver/ToolChains/Linux.cpp

@@ -247,6 +247,14 @@ Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
     ExtraOpts.push_back("relro");
   }
 
+  // The lld default page size is too large for Aarch64, which produces much
+  // larger .so files and images for arm64 device targets. Use 4KB page size
+  // for Android arm64 targets instead.
+  if (Triple.isAArch64() && Triple.isAndroid()) {
+    ExtraOpts.push_back("-z");
+    ExtraOpts.push_back("max-page-size=4096");
+  }
+
   if (GCCInstallation.getParentLibPath().find("opt/rh/devtoolset") !=
       StringRef::npos)
     // With devtoolset on RHEL, we want to add a bin directory that is relative

clang/test/Driver/android-aarch64-link.cpp

@@ -12,6 +12,11 @@
 // RUN:   -mcpu=cortex-a57 -### -v %s 2> %t
 // RUN: FileCheck -check-prefix=CORTEX-A57 < %t %s
 //
+// RUN: %clang -target aarch64-none-linux-android \
+// RUN:   -### -v %s 2> %t
+// RUN: FileCheck -check-prefix=MAX-PAGE-SIZE < %t %s
+//
 // GENERIC-ARM: --fix-cortex-a53-843419
 // CORTEX-A53: --fix-cortex-a53-843419
 // CORTEX-A57-NOT: --fix-cortex-a53-843419
+// MAX-PAGE-SIZE: max-page-size=4096