[LoongArch] Emit error messages when using emulated TLS #92483

wangleiat · 2024-05-17T01:48:44Z

No description provided.

Created using spr 1.3.5-bogner

llvmbot · 2024-05-17T01:49:19Z

@llvm/pr-subscribers-backend-loongarch

Author: wanglei (wangleiat)

Changes

Some developers are currently porting OpenHOS to LoongArch, which
requires support for emulated TLS. We should support it like RISC-V.

Full diff: https://github.com/llvm/llvm-project/pull/92483.diff

2 Files Affected:

(modified) llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp (+3)
(added) llvm/test/CodeGen/LoongArch/emutls.ll (+133)

diff --git a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
index fe2c613b1b30f..0b22ba50ee30f 100644
--- a/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
+++ b/llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
@@ -934,6 +934,9 @@ LoongArchTargetLowering::lowerGlobalTLSAddress(SDValue Op,
   GlobalAddressSDNode *N = cast<GlobalAddressSDNode>(Op);
   assert(N->getOffset() == 0 && "unexpected offset in global node");
 
+  if (DAG.getTarget().useEmulatedTLS())
+    return LowerToTLSEmulatedModel(N, DAG);
+
   bool IsDesc = DAG.getTarget().useTLSDESC();
 
   switch (getTargetMachine().getTLSModel(N->getGlobal())) {
diff --git a/llvm/test/CodeGen/LoongArch/emutls.ll b/llvm/test/CodeGen/LoongArch/emutls.ll
new file mode 100644
index 0000000000000..56ec8e3715f38
--- /dev/null
+++ b/llvm/test/CodeGen/LoongArch/emutls.ll
@@ -0,0 +1,133 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
+; RUN: llc --mtriple=loongarch32 -emulated-tls -relocation-model=pic < %s \
+; RUN:     | FileCheck -check-prefix=LA32 %s
+; RUN: llc --mtriple=loongarch64 -emulated-tls -relocation-model=pic < %s \
+; RUN:     | FileCheck -check-prefix=LA64 %s
+
+@external_x = external thread_local global i32, align 8
+@y = thread_local global i8 7, align 2
+@internal_z = internal thread_local global i64 9, align 16
+
+define ptr @get_external_x() nounwind {
+; LA32-LABEL: get_external_x:
+; LA32:       # %bb.0: # %entry
+; LA32-NEXT:    addi.w $sp, $sp, -16
+; LA32-NEXT:    st.w $ra, $sp, 12 # 4-byte Folded Spill
+; LA32-NEXT:    pcalau12i $a0, %got_pc_hi20(__emutls_v.external_x)
+; LA32-NEXT:    ld.w $a0, $a0, %got_pc_lo12(__emutls_v.external_x)
+; LA32-NEXT:    bl %plt(__emutls_get_address)
+; LA32-NEXT:    ld.w $ra, $sp, 12 # 4-byte Folded Reload
+; LA32-NEXT:    addi.w $sp, $sp, 16
+; LA32-NEXT:    ret
+;
+; LA64-LABEL: get_external_x:
+; LA64:       # %bb.0: # %entry
+; LA64-NEXT:    addi.d $sp, $sp, -16
+; LA64-NEXT:    st.d $ra, $sp, 8 # 8-byte Folded Spill
+; LA64-NEXT:    pcalau12i $a0, %got_pc_hi20(__emutls_v.external_x)
+; LA64-NEXT:    ld.d $a0, $a0, %got_pc_lo12(__emutls_v.external_x)
+; LA64-NEXT:    bl %plt(__emutls_get_address)
+; LA64-NEXT:    ld.d $ra, $sp, 8 # 8-byte Folded Reload
+; LA64-NEXT:    addi.d $sp, $sp, 16
+; LA64-NEXT:    ret
+entry:
+  ret ptr @external_x
+}
+
+define ptr @get_y() nounwind {
+; LA32-LABEL: get_y:
+; LA32:       # %bb.0: # %entry
+; LA32-NEXT:    addi.w $sp, $sp, -16
+; LA32-NEXT:    st.w $ra, $sp, 12 # 4-byte Folded Spill
+; LA32-NEXT:    pcalau12i $a0, %got_pc_hi20(__emutls_v.y)
+; LA32-NEXT:    ld.w $a0, $a0, %got_pc_lo12(__emutls_v.y)
+; LA32-NEXT:    bl %plt(__emutls_get_address)
+; LA32-NEXT:    ld.w $ra, $sp, 12 # 4-byte Folded Reload
+; LA32-NEXT:    addi.w $sp, $sp, 16
+; LA32-NEXT:    ret
+;
+; LA64-LABEL: get_y:
+; LA64:       # %bb.0: # %entry
+; LA64-NEXT:    addi.d $sp, $sp, -16
+; LA64-NEXT:    st.d $ra, $sp, 8 # 8-byte Folded Spill
+; LA64-NEXT:    pcalau12i $a0, %got_pc_hi20(__emutls_v.y)
+; LA64-NEXT:    ld.d $a0, $a0, %got_pc_lo12(__emutls_v.y)
+; LA64-NEXT:    bl %plt(__emutls_get_address)
+; LA64-NEXT:    ld.d $ra, $sp, 8 # 8-byte Folded Reload
+; LA64-NEXT:    addi.d $sp, $sp, 16
+; LA64-NEXT:    ret
+entry:
+  ret ptr @y
+}
+
+define ptr @get_internal_z() nounwind {
+; LA32-LABEL: get_internal_z:
+; LA32:       # %bb.0: # %entry
+; LA32-NEXT:    addi.w $sp, $sp, -16
+; LA32-NEXT:    st.w $ra, $sp, 12 # 4-byte Folded Spill
+; LA32-NEXT:    pcalau12i $a0, %pc_hi20(__emutls_v.internal_z)
+; LA32-NEXT:    addi.w $a0, $a0, %pc_lo12(__emutls_v.internal_z)
+; LA32-NEXT:    bl %plt(__emutls_get_address)
+; LA32-NEXT:    ld.w $ra, $sp, 12 # 4-byte Folded Reload
+; LA32-NEXT:    addi.w $sp, $sp, 16
+; LA32-NEXT:    ret
+;
+; LA64-LABEL: get_internal_z:
+; LA64:       # %bb.0: # %entry
+; LA64-NEXT:    addi.d $sp, $sp, -16
+; LA64-NEXT:    st.d $ra, $sp, 8 # 8-byte Folded Spill
+; LA64-NEXT:    pcalau12i $a0, %pc_hi20(__emutls_v.internal_z)
+; LA64-NEXT:    addi.d $a0, $a0, %pc_lo12(__emutls_v.internal_z)
+; LA64-NEXT:    bl %plt(__emutls_get_address)
+; LA64-NEXT:    ld.d $ra, $sp, 8 # 8-byte Folded Reload
+; LA64-NEXT:    addi.d $sp, $sp, 16
+; LA64-NEXT:    ret
+entry:
+  ret ptr @internal_z
+}
+
+; UTC_ARGS: --disable
+
+; LA32:        .data
+; LA32:        .globl __emutls_v.y
+; LA32:        .p2align 2
+; LA32-LABEL:  __emutls_v.y:
+; LA32-NEXT:     .word 1
+; LA32-NEXT:     .word 2
+; LA32-NEXT:     .word 0
+; LA32-NEXT:     .word __emutls_t.y
+; LA32:        .section .rodata,
+; LA32-LABEL:  __emutls_t.y:
+; LA32-NEXT:     .byte 7
+; LA32:        .data
+; LA32:        .p2align 2
+; LA32-LABEL:  __emutls_v.internal_z:
+; LA32-NEXT:     .word 8
+; LA32-NEXT:     .word 16
+; LA32-NEXT:     .word 0
+; LA32-NEXT:     .word __emutls_t.internal_z
+; LA32:        .section .rodata,
+; LA32-LABEL:  __emutls_t.internal_z:
+; LA32-NEXT:     .dword 9
+
+; LA64:        .data
+; LA64:        .globl __emutls_v.y
+; LA64:        .p2align 3
+; LA64-LABEL:  __emutls_v.y:
+; LA64-NEXT:     .dword 1
+; LA64-NEXT:     .dword 2
+; LA64-NEXT:     .dword 0
+; LA64-NEXT:     .dword __emutls_t.y
+; LA64:        .section .rodata,
+; LA64-LABEL:  __emutls_t.y:
+; LA64-NEXT:     .byte 7
+; LA64:        .data
+; LA64:        .p2align 3
+; LA64-LABEL:  __emutls_v.internal_z:
+; LA64-NEXT:     .dword 8
+; LA64-NEXT:     .dword 16
+; LA64-NEXT:     .dword 0
+; LA64-NEXT:     .dword __emutls_t.internal_z
+; LA64:        .section .rodata,
+; LA64-LABEL:  __emutls_t.internal_z:
+; LA64-NEXT:     .dword 9

wangleiat · 2024-05-17T01:51:06Z

Hi @MaskRay
Previous discussion: https://reviews.llvm.org/D141183. Despite the numerous drawbacks of emulated TLS, there is still some demand for it. If you still insist that the LoongArch backend should not support emulated TLS, then we should at least provide users with clear warnings either in the frontend or during the downgrading process.
Perhaps like this:

if (DAG.getTarget().useEmulatedTLS())
  report_fatal_error("The emulated TLS is prohibited");

Otherwise, this issue will be reported as 'some symbols undefined' errors during the linking phase, which can be very confusing.

wangleiat · 2024-05-17T01:51:35Z

@xen0n

xen0n · 2024-05-23T09:01:52Z

Can we (and preferably also the OHOS porters) sort out and try to remove the emulated TLS usage in the OHOS codebase instead? At least we would know exactly why it is necessary if it eventually turns out to be the case.

SixWeining · 2024-05-23T15:23:31Z

@yetist may be interested in this PR.

SixWeining · 2024-05-24T01:08:55Z

Can we (and preferably also the OHOS porters) sort out and try to remove the emulated TLS usage in the OHOS codebase instead? At least we would know exactly why it is necessary if it eventually turns out to be the case.

I heard that currently some services in OHOS use coroutine which depends on emulated TLS, but I don't know the details. I also heard they plan to remove the dependency and switch to ELF TLS in future versions.

So I prefer reporting error in somewhere (ether in clang or backend) if emulated TLS is used on LoongArch.

Created using spr 1.3.5-bogner

wangleiat · 2024-06-06T02:54:19Z

Hi all:
How about emitting an error message like this?

SixWeining

LGTM

llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp

MaskRay · 2024-06-06T04:03:08Z

Instead of an error for each TLS instance, emit it in TargetMachine ?

Created using spr 1.3.5-bogner

wangleiat · 2024-06-06T06:23:39Z

Instead of an error for each TLS instance, emit it in TargetMachine ?

I didn't find a way to emit an error message and return the error to the error handler. Either use report_fatal_error ?

Created using spr 1.3.5-bogner

MaskRay · 2024-06-07T03:22:03Z

Instead of an error for each TLS instance, emit it in TargetMachine ?

I didn't find a way to emit an error message and return the error to the error handler. Either use report_fatal_error ?

Seems fine. report_fatal_error with false GenCrashDiag?

wangleiat · 2024-06-07T03:34:44Z

Instead of an error for each TLS instance, emit it in TargetMachine ?

I didn't find a way to emit an error message and return the error to the error handler. Either use report_fatal_error ?

Seems fine. report_fatal_error with false GenCrashDiag?

Does adding such test cases increase the testing time if useing report_fatal_error?

[𝘀𝗽𝗿] initial version

2628bad

Created using spr 1.3.5-bogner

llvmbot added the backend:loongarch label May 17, 2024

wangleiat requested review from SixWeining and MaskRay May 17, 2024 01:51

Emit error messages when using emulated TLS

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Created using spr 1.3.5-bogner

wangleiat changed the title ~~[LoongArch] Support emulated TLS~~ [LoongArch] Emit error messages when using emulated TLS Jun 6, 2024

SixWeining approved these changes Jun 6, 2024

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MaskRay reviewed Jun 6, 2024

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[LoongArch] Emit error messages when using emulated TLS #92483

[LoongArch] Emit error messages when using emulated TLS #92483

wangleiat commented May 17, 2024 •

edited

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wangleiat commented Jun 7, 2024

[LoongArch] Emit error messages when using emulated TLS #92483

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[LoongArch] Emit error messages when using emulated TLS #92483

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wangleiat commented May 17, 2024 • edited

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