[LLVM][OHOS] Use emulated TLS for OHOS platform

[kpdev42]

Summary

Both Linux and LiteOS for all OpenHarmony targets use emulated TLS

~~~

Huawei RRI, OS Lab

[DavidSpickett]

Both Linux and LiteOS for all OpenHarmony targets use emulated TLS

What does the LiteOS triple look like, should it be tested too?

[kpdev42]

The only supported arch for liteos is arm32

[DavidSpickett]

LGTM.

[DavidSpickett]

Though one last thing, should MIPS be mentioned here? https://reviews.llvm.org/D145227 adds targets for MIPS as well, do you not use emulated TLS there?

[jrtc27]

llvm/test/CodeGen/RISCV/emutls.ll

1 ↗

(On Diff #504635)

NACK for this test, just add your RUN lines to the one in the patch that adds emutls support to RISC-V.

llvm/test/CodeGen/RISCV/emutls_generic.ll

1 ↗

(On Diff #504635)

NACK to this too, duplicates

[kpdev42]

llvm/test/CodeGen/RISCV/emutls.ll

1 ↗

(On Diff #504635)

Excuse me, do you mean that it is better to prepare a separate patch for RISC-V, right?

[jrtc27]

llvm/test/CodeGen/RISCV/emutls.ll

1 ↗

(On Diff #504635)

D143708 adds emulated TLS support (which I assume is what you're using, since this patch doesn't modify the backend to support it) and includes a test for that. You are not adding emulated TLS support here, you're just changing a default, so you shouldn't be writing your own (worse) test for emulated TLS code generation, you should just be adding RUN lines to the test in the patch you're basing this on.

[kpdev42]

Updated after D143708 landed

[kpdev42]

@jrtc27 Patch was updated, please take a look

[DavidSpickett]

Though one last thing, should MIPS be mentioned here? https://reviews.llvm.org/D145227 adds targets for MIPS as well, do you not use emulated TLS there?

Is still outstanding, otherwise no objections.

[jrtc27]

One remaining nit as far as I can tell

llvm/test/CodeGen/ARM/emutls.ll

5 ↗

(On Diff #511359)

Leave this line alone

[kpdev42]

Address review comments

[MaskRay]

This patch adds too many RUN lines. I don't think enumerating every combination for your target triple makes good use of the number of RUN lines. Every RUN line adds a small overhead for all users.
I think adding a line to llvm/test/CodeGen/X86/emutls-pic.ll testing that emulated TLS is used by default is sufficient.

[kpdev42]

Address review comment

[kpdev42]

@jrtc27 Please take a look

llvm/include/llvm/TargetParser/Triple.h

public:
   /// Tests whether the target supports comdat
   bool supportsCOMDAT() const {
     return !(isOSBinFormatMachO() || isOSBinFormatXCOFF() ||
              isOSBinFormatDXContainer());
   }
 
   /// Tests whether the target uses emulated TLS as default.
   bool hasDefaultEmulatedTLS() const {
-    return isAndroid() || isOSOpenBSD() || isWindowsCygwinEnvironment();
+    return isAndroid() || isOSOpenBSD() || isWindowsCygwinEnvironment() ||
+           isOHOSFamily();
   }
 
   /// Tests whether the target uses -data-sections as default.
   bool hasDefaultDataSections() const {
     return isOSBinFormatXCOFF() || isWasm();
   }
 
   /// Tests if the environment supports dllimport/export annotations.

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

 ; RUN: llc < %s -emulated-tls -mtriple=i386-linux-gnu -relocation-model=pic | FileCheck -check-prefix=X86 %s
 ; RUN: llc < %s -emulated-tls -mtriple=x86_64-linux-gnu -relocation-model=pic | FileCheck -check-prefix=X64 %s
 ; RUN: llc < %s -emulated-tls -mtriple=i386-linux-android -relocation-model=pic | FileCheck -check-prefix=X86 %s
 ; RUN: llc < %s -emulated-tls -mtriple=x86_64-linux-android -relocation-model=pic | FileCheck -check-prefix=X64 %s
 
 ; 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=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
+; RUN: llc < %s -mtriple=x86_64-linux-ohos -relocation-model=pic | FileCheck -check-prefix=X64 %s
 
 ; NoEMU-NOT: __emutls
 
 ; Use my_emutls_get_address like __emutls_get_address.
 @my_emutls_v_xyz = external global ptr, align 4
 declare ptr @my_emutls_get_address(ptr)
 
 define i32 @my_get_xyz() {