[Android] Use ELF TLS for Android API level 29+

Use ELF TLS by default instead of emulated TLS for Android build targets when
the API level is >= 29.

Android Q features full TLS support. See release notes
(https://developer.android.com/preview/features#elf-tls) and implementation details
(https://android.googlesource.com/platform/bionic/+/master/docs/elf-tls.md#Workaround_Use-Variant-2-on-arm32_arm64).

Reviewed By: rprichard, danalbert

Differential Revision: https://reviews.llvm.org/D147849

Author: brad0

llvm/include/llvm/TargetParser/Triple.h

@@ -979,9 +979,11 @@ class Triple {
   }
 
   /// Tests whether the target uses emulated TLS as default.
+  ///
+  /// Note: Android API level 29 (10) introduced ELF TLS.
   bool hasDefaultEmulatedTLS() const {
-    return isAndroid() || isOSOpenBSD() || isWindowsCygwinEnvironment() ||
-           isOHOSFamily();
+    return (isAndroid() && isAndroidVersionLT(29)) || isOSOpenBSD() ||
+           isWindowsCygwinEnvironment() || isOHOSFamily();
   }
 
   /// Tests whether the target uses -data-sections as default.

llvm/test/CodeGen/AArch64/emutls_generic.ll

@@ -18,6 +18,8 @@
 ; aarch64-windows-gnu needs explicit -emulated-tls
 ; RUN: llc < %s -mtriple=aarch64-apple-darwin -O3 \
 ; RUN:     | FileCheck -check-prefix=NoEMU %s
+; RUN: llc < %s -mtriple=aarch64-linux-android29 -O3 \
+; RUN:     | FileCheck -check-prefix=NoEMU %s
 
 ; NoEMU-NOT: __emutls
 

llvm/test/CodeGen/X86/emutls-pic.ll

@@ -5,6 +5,7 @@
 
 ; RUN: llc < %s -mtriple=i386-linux-gnu -relocation-model=pic | FileCheck -check-prefix=NoEMU %s
 ; RUN: llc < %s -mtriple=x86_64-linux-gnu -relocation-model=pic | FileCheck -check-prefix=NoEMU %s
+; RUN: llc < %s -mtriple=x86_64-linux-android29 -relocation-model=pic | FileCheck -check-prefix=NoEMU %s
 ; RUN: llc < %s -mtriple=i386-linux-android -relocation-model=pic | FileCheck -check-prefix=X86 %s
 ; RUN: llc < %s -mtriple=x86_64-linux-android -relocation-model=pic | FileCheck -check-prefix=X64 %s
 ; RUN: llc < %s -mtriple=i386-linux-ohos -relocation-model=pic | FileCheck -check-prefix=X86 %s

llvm/test/CodeGen/X86/emutls-pie.ll

@@ -11,6 +11,8 @@
 ; RUN:   | FileCheck -check-prefix=NoEMU %s
 ; RUN: llc < %s -mcpu=generic -mtriple=x86_64-linux-gnu -relocation-model=pic \
 ; RUN:   | FileCheck -check-prefix=NoEMU %s
+; RUN: llc < %s -mcpu=generic -mtriple=i386-linux-android29 -relocation-model=pic \
+; RUN:   | FileCheck -check-prefix=NoEMU %s
 ; RUN: llc < %s -mcpu=generic -mtriple=i386-linux-android -relocation-model=pic \
 ; RUN:   | FileCheck -check-prefix=X86 %s
 ; RUN: llc < %s -mcpu=generic -mtriple=x86_64-linux-android -relocation-model=pic \

llvm/test/CodeGen/X86/emutls_generic.ll

@@ -15,6 +15,8 @@
 ; RUN:     | FileCheck -check-prefix=X86_64 %s
 ; RUN: llc < %s -mtriple=i386-linux-gnu -relocation-model=pic \
 ; RUN:     | FileCheck -check-prefix=NoEMU %s
+; RUN: llc < %s -mtriple=i686-linux-android29 -relocation-model=pic \
+; RUN:     | FileCheck -check-prefix=NoEMU %s
 
 ; NoEMU-NOT: __emutls
 

llvm/test/CodeGen/X86/fast-isel-emutls.ll

@@ -1,6 +1,8 @@
 ; RUN: llc < %s -emulated-tls -relocation-model=pic -mtriple=i686-unknown-linux-gnu -fast-isel | FileCheck %s
 ; RUN: llc < %s -relocation-model=pic -mtriple=i686-unknown-linux-gnu -fast-isel \
 ; RUN: | FileCheck -check-prefix=NoEMU %s
+; RUN: llc < %s -relocation-model=pic -mtriple=i686-linux-android29 -fast-isel \
+; RUN: | FileCheck -check-prefix=NoEMU %s
 ; PR3654
 
 ; NoEMU-NOT: __emutls