[ELF/AArch64] Add aarch64 TLS IE to LE relax for local symbol test

[zatrazz]

Summary

This patch add a TLS relax optimization test when transforming
Initial-Exec to Local-Exec for local symbols (which can not be preempted).

This patch is based upon http://reviews.llvm.org/D18332

[grimar]

This one fixes only test it seems ? Looks you forgot to provide source code change, or:

when you write "This patch is based upon xxx", why don't you just put that one as dependency ?

[zatrazz]

In fact the rebase against your patch to implement TLSDESC made the changes not necessary. The original change as basically:

bool AArch64TargetInfo::needsGot(uint32_t Type, SymbolBody &S) const {

• if (Type == R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC ||
• Type == R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21)
• return true;

+ if (isTlsInitialExecRel(Type))
+ return canBePreempted(&S);

Where the TLSDESC [1] now does:

bool AArch64TargetInfo::refersToGotEntry(uint32_t Type,

                                       const SymbolBody &S) const {
switch (Type) {
case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
  return !canRelaxTls(Type, &S);
case R_AARCH64_ADR_GOT_PAGE:
case R_AARCH64_LD64_GOT_LO12_NC:
  return true;
default:
  return false;
}

}

bool AArch64TargetInfo::needsGot(uint32_t Type, SymbolBody &S) const {

return refersToGotEntry(Type, S) || needsPlt<ELF64LE>(Type, S);

}

Where 'canRelaxTls' now have the snippet required:

// Initial-Exec relocs can be relaxed to Local-Exec if the symbol is locally
// defined.
if (isTlsInitialExecRel(Type))
  return !S->isPreemptible();

So maybe to rename this change to 'Add aarch64 TLS IE to LE relax for local symbol test'?

[1] http://reviews.llvm.org/D18330

[grimar]

In D18333#379889, @zatrazz wrote:

In fact the rebase against your patch to implement TLSDESC made the changes not necessary. The original change as basically:
...
So maybe to rename this change to 'Add aarch64 TLS IE to LE relax for local symbol test'?

[1] http://reviews.llvm.org/D18330

Yes, I think you need to change the description and commit text accordingly to what this patch actually do.

[zatrazz]

Ping.

[rengolin]

test/ELF/aarch64-tls-iele.s

17

I think there should be an "ldr" in between these two pairs, in which case the test would fail?

Either adding a:

CHECK-NEXT: ldr

in between the two pairs, or changing the third line to:

CHECK: 11008:  00 00 a0 d2   movz   x0, #0, lsl #16

should work.

[zatrazz]

test/ELF/aarch64-tls-iele.s

17

There is no need of 'ldr' because the idea of TLS IE to LE isto exactly remove the ldr and changing it to movz.

[rengolin]

Right, makes sense to me. It's just a test, so I'll risk an approval. :)

LGTM.

test/ELF/aarch64-tls-iele.s

 # RUN: llvm-mc -filetype=obj -triple=aarch64-unknown-linux %p/Inputs/aarch64-tls-ie.s -o %ttlsie.o
 # RUN: llvm-mc -filetype=obj -triple=aarch64-unknown-linux %s -o %tmain.o
 # RUN: ld.lld %tmain.o %ttlsie.o -o %tout
 # RUN: llvm-objdump -d %tout | FileCheck %s
 # RUN: llvm-readobj -s -r %tout | FileCheck -check-prefix=RELOC %s
 # REQUIRES: aarch64
 
-#Local-Dynamic to Initial-Exec relax creates no
-#RELOC:      Relocations [
-#RELOC-NEXT: ]
+# Initial-Exec to Local-Exec relax creates no dynamic relocations.
+# RELOC:      Relocations [
+# RELOC-NEXT: ]
 
 # TCB size = 0x16 and foo is first element from TLS register.
-#CHECK: Disassembly of section .text:
-#CHECK: _start:
-#CHECK:  11000: 00 00 a0 d2 movz  x0, #0, lsl #16
-#CHECK:  11004: 00 02 80 f2   movk  x0, #0x10
+# CHECK: Disassembly of section .text:
+# CHECK: _start:
+# CHECK-NEXT: 11000:  00 00 a0 d2   movz   x0, #0, lsl #16
+# CHECK-NEXT: 11004:  80 02 80 f2   movk   x0, #0x14
+# CHECK-NEXT: 11008:  00 00 a0 d2   movz   x0, #0, lsl #16
+# CHECK-NEXT: 1100c:  00 02 80 f2   movk   x0, #0x10
+
+.section .tdata
+.align 2
+.type foo_local, %object
+.size foo_local, 4
+foo_local:
+.word 5
+.text
 
 .globl _start
 _start:
  adrp    x0, :gottprel:foo
  ldr     x0, [x0, :gottprel_lo12:foo]
+ adrp    x0, :gottprel:foo_local
+ ldr     x0, [x0, :gottprel_lo12:foo_local]