[ELF/AARCH64] - Implemented R_AARCH64_TSTBR14 relocation.

[grimar]

Summary

R_AARCH64_TSTBR14 is calculated as S+A-P,
Set the immediate field of a TBZ/TBNZ instruction to bits [15:2] of X; check -2^15 ≤ X < 2^15

[ruiu]

LGTM

lld/trunk/ELF/Target.cpp

bool AArch64TargetInfo::relocNeedsPlt(uint32_t Type,
   if (isGnuIFunc<ELF64LE>(S))
     return true;
   switch (Type) {
   default:
     return false;
   case R_AARCH64_CALL26:
   case R_AARCH64_CONDBR19:
   case R_AARCH64_JUMP26:
+  case R_AARCH64_TSTBR14:
     return canBePreempted(&S, true);
   }
 }
 
 static void updateAArch64Adr(uint8_t *L, uint64_t Imm) {
   uint32_t ImmLo = (Imm & 0x3) << 29;
   uint32_t ImmHi = ((Imm & 0x1FFFFC) >> 2) << 5;
   uint64_t Mask = (0x3 << 29) | (0x7FFFF << 5);
case R_AARCH64_PREL16:
     break;
   case R_AARCH64_PREL32:
     checkIntUInt<32>(SA - P, Type);
     write32le(Loc, SA - P);
     break;
   case R_AARCH64_PREL64:
     write64le(Loc, SA - P);
     break;
+  case R_AARCH64_TSTBR14: {
+    uint64_t X = SA - P;
+    checkInt<16>(X, Type);
+    or32le(Loc, (X & 0xFFFC) << 3);
+    break;
+  }
   default:
     error("unrecognized reloc " + Twine(Type));
   }
 }
 
 AMDGPUTargetInfo::AMDGPUTargetInfo() {}
 
 void AMDGPUTargetInfo::writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const {

lld/trunk/test/ELF/Inputs/aarch64-tstbr14-reloc.s

+.globl _foo
+_foo:
+ nop
+ nop
+ nop
+ nop
+
+.globl _bar
+_bar:
+ nop
+ nop
+ nop

lld/trunk/test/ELF/aarch64-tstbr14-reloc.s

+# RUN: llvm-mc -filetype=obj -triple=aarch64-unknown-freebsd %p/Inputs/aarch64-tstbr14-reloc.s -o %t1
+# RUN: llvm-mc -filetype=obj -triple=aarch64-unknown-freebsd %s -o %t2
+# RUN: ld.lld %t1 %t2 -o %t
+# RUN: llvm-objdump -d %t | FileCheck %s
+# RUN: ld.lld -shared %t1 %t2 -o %t3
+# RUN: llvm-objdump -d %t3 | FileCheck -check-prefix=DSO %s
+# RUN: llvm-readobj -s -r %t3 | FileCheck -check-prefix=DSOREL %s
+# REQUIRES: aarch64
+
+# 0x1101c - 28 = 0x11000
+# 0x11020 - 16 = 0x11010
+# 0x11024 - 36 = 0x11000
+# 0x11028 - 24 = 0x11010
+# CHECK:      Disassembly of section .text:
+# CHECK-NEXT: _foo:
+# CHECK-NEXT:  11000: {{.*}} nop
+# CHECK-NEXT:  11004: {{.*}} nop
+# CHECK-NEXT:  11008: {{.*}} nop
+# CHECK-NEXT:  1100c: {{.*}} nop
+# CHECK:      _bar:
+# CHECK-NEXT:  11010: {{.*}} nop
+# CHECK-NEXT:  11014: {{.*}} nop
+# CHECK-NEXT:  11018: {{.*}} nop
+# CHECK:      _start:
+# CHECK-NEXT:  1101c: {{.*}} tbnz w3, #15, #-28
+# CHECK-NEXT:  11020: {{.*}} tbnz w3, #15, #-16
+# CHECK-NEXT:  11024: {{.*}} tbz x6, #45, #-36
+# CHECK-NEXT:  11028: {{.*}} tbz x6, #45, #-24
+
+#DSOREL:      Section {
+#DSOREL:        Index:
+#DSOREL:        Name: .got.plt
+#DSOREL-NEXT:   Type: SHT_PROGBITS
+#DSOREL-NEXT:   Flags [
+#DSOREL-NEXT:     SHF_ALLOC
+#DSOREL-NEXT:     SHF_WRITE
+#DSOREL-NEXT:   ]
+#DSOREL-NEXT:   Address: 0x3000
+#DSOREL-NEXT:   Offset: 0x3000
+#DSOREL-NEXT:   Size: 40
+#DSOREL-NEXT:   Link: 0
+#DSOREL-NEXT:   Info: 0
+#DSOREL-NEXT:   AddressAlignment: 8
+#DSOREL-NEXT:   EntrySize: 0
+#DSOREL-NEXT:  }
+#DSOREL:      Relocations [
+#DSOREL-NEXT:  Section ({{.*}}) .rela.plt {
+#DSOREL-NEXT:    0x3018 R_AARCH64_JUMP_SLOT _foo
+#DSOREL-NEXT:    0x3020 R_AARCH64_JUMP_SLOT _bar
+#DSOREL-NEXT:  }
+#DSOREL-NEXT:]
+
+#DSO:      Disassembly of section .text:
+#DSO-NEXT: _foo:
+#DSO-NEXT:  1000: {{.*}} nop
+#DSO-NEXT:  1004: {{.*}} nop
+#DSO-NEXT:  1008: {{.*}} nop
+#DSO-NEXT:  100c: {{.*}} nop
+#DSO:      _bar:
+#DSO-NEXT:  1010: {{.*}} nop
+#DSO-NEXT:  1014: {{.*}} nop
+#DSO-NEXT:  1018: {{.*}} nop
+#DSO:      _start:
+# 0x101c + 52 = 0x1050 = PLT[1]
+# 0x1020 + 64 = 0x1060 = PLT[2]
+# 0x1024 + 44 = 0x1050 = PLT[1]
+# 0x1028 + 56 = 0x1060 = PLT[2]
+#DSO-NEXT:  101c: {{.*}} tbnz w3, #15, #52
+#DSO-NEXT:  1020: {{.*}} tbnz w3, #15, #64
+#DSO-NEXT:  1024: {{.*}} tbz x6, #45, #44
+#DSO-NEXT:  1028: {{.*}} tbz x6, #45, #56
+#DSO-NEXT: Disassembly of section .plt:
+#DSO-NEXT: .plt:
+#DSO-NEXT:  1030: {{.*}} stp x16, x30, [sp, #-16]!
+#DSO-NEXT:  1034: {{.*}} adrp x16, #8192
+#DSO-NEXT:  1038: {{.*}} ldr x17, [x16, #16]
+#DSO-NEXT:  103c: {{.*}} add x16, x16, #16
+#DSO-NEXT:  1040: {{.*}} br x17
+#DSO-NEXT:  1044: {{.*}} nop
+#DSO-NEXT:  1048: {{.*}} nop
+#DSO-NEXT:  104c: {{.*}} nop
+#DSO-NEXT:  1050: {{.*}} adrp x16, #8192
+#DSO-NEXT:  1054: {{.*}} ldr x17, [x16, #24]
+#DSO-NEXT:  1058: {{.*}} add x16, x16, #24
+#DSO-NEXT:  105c: {{.*}} br x17
+#DSO-NEXT:  1060: {{.*}} adrp x16, #8192
+#DSO-NEXT:  1064: {{.*}} ldr x17, [x16, #32]
+#DSO-NEXT:  1068: {{.*}} add x16, x16, #32
+#DSO-NEXT:  106c: {{.*}} br x17
+
+.globl _start
+_start:
+ tbnz w3, #15, _foo
+ tbnz w3, #15, _bar
+ tbz x6, #45, _foo
+ tbz x6, #45, _bar