Add support for TLS IEGOT relocations

[sidneym]

Summary

Adds support for IEGOT relocations.

The patch includes references to:

https://reviews.llvm.org/D71069
https://reviews.llvm.org/D71143

The file referenced in Inputs is from: https://reviews.llvm.org/D71143

I can merge the file in Inputs into the testscases but I think the duplication would be an issue.

[MaskRay]

lld/test/ELF/hexagon-tls-ie-got.s

1

Probably delete -got from the filename. Initial Exec uses GOT on all targets.

3

You can place the definitions in the same file. A definition in a DSO is by default preemptible (unless marked as non-STV_DEFAULT, or -Bsymbolic)

See ppc32-tls-ie.s for an example.

7

In the previous review, you mentioned that Hexagon does not support TLS relaxations. It is worth testing this property explicitly. See the ld.lld %t.o -o %t and LE: LE-NEXT: part of ppc32-tls-ie.s.

lld/ELF/Arch/Hexagon.cpp

Hexagon::Hexagon() {
   gotPltHeaderEntriesNum = 4;
 
   pltEntrySize = 16;
   pltHeaderSize = 32;
 
   // Hexagon Linux uses 64K pages by default.
   defaultMaxPageSize = 0x10000;
   noneRel = R_HEX_NONE;
+  tlsGotRel = R_HEX_TPREL_32;
 }
 
 uint32_t Hexagon::calcEFlags() const {
   assert(!objectFiles.empty());
 
   // The architecture revision must always be equal to or greater than
   // greatest revision in the list of inputs.
   uint32_t ret = 0;
RelExpr Hexagon::getRelExpr(RelType type, const Symbol &s,
   case R_HEX_GOTREL_16_X:
   case R_HEX_GOTREL_32_6_X:
   case R_HEX_GOTREL_HI16:
   case R_HEX_GOTREL_LO16:
     return R_GOTPLTREL;
   case R_HEX_GOT_11_X:
   case R_HEX_GOT_16_X:
   case R_HEX_GOT_32_6_X:
+  case R_HEX_IE_GOT_11_X:
+  case R_HEX_IE_GOT_16_X:
+  case R_HEX_IE_GOT_32_6_X:
+  case R_HEX_IE_GOT_HI16:
+  case R_HEX_IE_GOT_LO16:
     return R_GOTPLT;
   case R_HEX_TPREL_11_X:
   case R_HEX_TPREL_16:
   case R_HEX_TPREL_16_X:
   case R_HEX_TPREL_32_6_X:
   case R_HEX_TPREL_HI16:
   case R_HEX_TPREL_LO16:
     return R_TLS;
case R_HEX_8_X:
     break;
   case R_HEX_9_X:
     or32le(loc, applyMask(0x00003fe0, val & 0x3f));
     break;
   case R_HEX_10_X:
     or32le(loc, applyMask(0x00203fe0, val & 0x3f));
     break;
   case R_HEX_11_X:
+  case R_HEX_IE_GOT_11_X:
   case R_HEX_GOT_11_X:
   case R_HEX_GOTREL_11_X:
   case R_HEX_TPREL_11_X:
     or32le(loc, applyMask(findMaskR11(read32le(loc)), val & 0x3f));
     break;
   case R_HEX_12_X:
     or32le(loc, applyMask(0x000007e0, val));
     break;
   case R_HEX_16_X: // These relocs only have 6 effective bits.
   case R_HEX_IE_16_X:
+  case R_HEX_IE_GOT_16_X:
   case R_HEX_GOT_16_X:
   case R_HEX_GOTREL_16_X:
   case R_HEX_TPREL_16_X:
     or32le(loc, applyMask(findMaskR16(read32le(loc)), val & 0x3f));
     break;
   case R_HEX_TPREL_16:
     or32le(loc, applyMask(findMaskR16(read32le(loc)), val & 0xffff));
     break;
   case R_HEX_32:
   case R_HEX_32_PCREL:
     or32le(loc, val);
     break;
   case R_HEX_32_6_X:
   case R_HEX_GOT_32_6_X:
   case R_HEX_GOTREL_32_6_X:
+  case R_HEX_IE_GOT_32_6_X:
   case R_HEX_IE_32_6_X:
   case R_HEX_TPREL_32_6_X:
     or32le(loc, applyMask(0x0fff3fff, val >> 6));
     break;
   case R_HEX_B9_PCREL:
     checkInt(loc, val, 11, type);
     or32le(loc, applyMask(0x003000fe, val >> 2));
     break;
void Hexagon::relocateOne(uint8_t *loc, RelType type, uint64_t val) const {
   case R_HEX_B22_PCREL_X:
     or32le(loc, applyMask(0x1ff3ffe, val & 0x3f));
     break;
   case R_HEX_B32_PCREL_X:
     or32le(loc, applyMask(0x0fff3fff, val >> 6));
     break;
   case R_HEX_GOTREL_HI16:
   case R_HEX_HI16:
+  case R_HEX_IE_GOT_HI16:
   case R_HEX_IE_HI16:
   case R_HEX_TPREL_HI16:
     or32le(loc, applyMask(0x00c03fff, val >> 16));
     break;
   case R_HEX_GOTREL_LO16:
   case R_HEX_LO16:
+  case R_HEX_IE_GOT_LO16:
   case R_HEX_IE_LO16:
   case R_HEX_TPREL_LO16:
     or32le(loc, applyMask(0x00c03fff, val));
     break;
   default:
     llvm_unreachable("unknown relocation");
   }
 }

lld/test/ELF/hexagon-tls-ie-got.s

+# REQUIRES: hexagon
+# RUN: llvm-mc -filetype=obj -triple=hexagon-unknown-elf %s -o %t1.o
+# RUN: llvm-mc -filetype=obj -triple=hexagon-unknown-elf %p/Inputs/hexagon-tls-ie.s -o %t2.o
+# RUN: ld.lld -shared %t1.o %t2.o -o %t
+# RUN: llvm-objdump -d --print-imm-hex %t | FileCheck %s
+# RUN: llvm-readelf -r  %t | FileCheck -check-prefix=CHECK-RELA %s
+
+  .globl  _start
+  .type _start, @function
+_start:
+
+# R_HEX_IEGOT_32_6_X and R_HEX_IEGOT_16_X
+# CHECK:      { immext(#0xfffeffc0)
+# CHECK-NEXT:   r2 = memw(##0xfffefff0) }
+    r2 = memw(##a@IEGOT)
+
+# R_HEX_IEGOT_LO16
+# CHECK: { r2.l = #0xfff0 }
+    r2.l = #a@IEGOT
+# R_HEX_IEGOT_HI16
+# CHECK: { r2.h = #0xfffe }
+    r2.h = #a@IEGOT
+
+# CHECK-RELA:     Relocation section '.rela.dyn'
+# CHECK-RELA-NEXT: Offset     Info    Type                Sym. Value  Symbol's Name + Addend
+# CHECK-RELA-NEXT:000202e4  0000023f R_HEX_TPREL_32         00000000   a + 0
+# CHECK-RELA-NEXT:000202e8  0000033f R_HEX_TPREL_32         00000004   b + 0
+# CHECK-RELA-NEXT:000202ec  0000043f R_HEX_TPREL_32         00000008   c + 0
+# CHECK-RELA-NEXT:000202f0  0000053f R_HEX_TPREL_32         0000000c   d + 0
+
+    r2 = memw(##b@IEGOT)
+    r2 = memw(##c@IEGOT)
+    r2 = memw(##d@IEGOT)