[libcxx-commits] [mlir] [libunwind] [lld] [flang] [clang-tools-extra] [libc] [libcxx] [llvm] [clang] [compiler-rt] [lldb] [ELF] Implement R_RISCV_TLSDESC for RISC-V (PR #79239)

Fangrui Song via libcxx-commits libcxx-commits at lists.llvm.org
Wed Jan 24 22:23:27 PST 2024


https://github.com/MaskRay updated https://github.com/llvm/llvm-project/pull/79239

>From 3725fa4eac3d3d946289d7eb7213f3a1751a2770 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Tue, 23 Jan 2024 17:58:07 -0800
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
 =?UTF-8?q?l=20version?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Created using spr 1.3.4
---
 lld/ELF/Arch/RISCV.cpp                | 158 +++++++++++++++++----
 lld/ELF/Relocations.cpp               |  25 ++--
 lld/test/ELF/riscv-tlsdesc-gd-mixed.s |  26 ++++
 lld/test/ELF/riscv-tlsdesc-relax.s    | 125 +++++++++++++++++
 lld/test/ELF/riscv-tlsdesc.s          | 192 ++++++++++++++++++++++++++
 5 files changed, 492 insertions(+), 34 deletions(-)
 create mode 100644 lld/test/ELF/riscv-tlsdesc-gd-mixed.s
 create mode 100644 lld/test/ELF/riscv-tlsdesc-relax.s
 create mode 100644 lld/test/ELF/riscv-tlsdesc.s

diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp
index d7d3d3e47814971..67d7e2562e9b178 100644
--- a/lld/ELF/Arch/RISCV.cpp
+++ b/lld/ELF/Arch/RISCV.cpp
@@ -61,6 +61,7 @@ enum Op {
   AUIPC = 0x17,
   JALR = 0x67,
   LD = 0x3003,
+  LUI = 0x37,
   LW = 0x2003,
   SRLI = 0x5013,
   SUB = 0x40000033,
@@ -73,6 +74,7 @@ enum Reg {
   X_T0 = 5,
   X_T1 = 6,
   X_T2 = 7,
+  X_A0 = 10,
   X_T3 = 28,
 };
 
@@ -102,6 +104,26 @@ static uint32_t setLO12_S(uint32_t insn, uint32_t imm) {
          (extractBits(imm, 4, 0) << 7);
 }
 
+namespace {
+struct SymbolAnchor {
+  uint64_t offset;
+  Defined *d;
+  bool end; // true for the anchor of st_value+st_size
+};
+} // namespace
+
+struct elf::RISCVRelaxAux {
+  // This records symbol start and end offsets which will be adjusted according
+  // to the nearest relocDeltas element.
+  SmallVector<SymbolAnchor, 0> anchors;
+  // For relocations[i], the actual offset is r_offset - (i ? relocDeltas[i-1] :
+  // 0).
+  std::unique_ptr<uint32_t[]> relocDeltas;
+  // For relocations[i], the actual type is relocTypes[i].
+  std::unique_ptr<RelType[]> relocTypes;
+  SmallVector<uint32_t, 0> writes;
+};
+
 RISCV::RISCV() {
   copyRel = R_RISCV_COPY;
   pltRel = R_RISCV_JUMP_SLOT;
@@ -119,6 +141,7 @@ RISCV::RISCV() {
     tlsGotRel = R_RISCV_TLS_TPREL32;
   }
   gotRel = symbolicRel;
+  tlsDescRel = R_RISCV_TLSDESC;
 
   // .got[0] = _DYNAMIC
   gotHeaderEntriesNum = 1;
@@ -187,6 +210,8 @@ int64_t RISCV::getImplicitAddend(const uint8_t *buf, RelType type) const {
   case R_RISCV_JUMP_SLOT:
     // These relocations are defined as not having an implicit addend.
     return 0;
+  case R_RISCV_TLSDESC:
+    return config->is64 ? read64le(buf + 8) : read32le(buf + 4);
   }
 }
 
@@ -295,6 +320,12 @@ RelExpr RISCV::getRelExpr(const RelType type, const Symbol &s,
   case R_RISCV_PCREL_LO12_I:
   case R_RISCV_PCREL_LO12_S:
     return R_RISCV_PC_INDIRECT;
+  case R_RISCV_TLSDESC_HI20:
+  case R_RISCV_TLSDESC_LOAD_LO12:
+  case R_RISCV_TLSDESC_ADD_LO12:
+    return R_TLSDESC_PC;
+  case R_RISCV_TLSDESC_CALL:
+    return R_TLSDESC_CALL;
   case R_RISCV_TLS_GD_HI20:
     return R_TLSGD_PC;
   case R_RISCV_TLS_GOT_HI20:
@@ -419,6 +450,7 @@ void RISCV::relocate(uint8_t *loc, const Relocation &rel, uint64_t val) const {
 
   case R_RISCV_GOT_HI20:
   case R_RISCV_PCREL_HI20:
+  case R_RISCV_TLSDESC_HI20:
   case R_RISCV_TLS_GD_HI20:
   case R_RISCV_TLS_GOT_HI20:
   case R_RISCV_TPREL_HI20:
@@ -430,6 +462,8 @@ void RISCV::relocate(uint8_t *loc, const Relocation &rel, uint64_t val) const {
   }
 
   case R_RISCV_PCREL_LO12_I:
+  case R_RISCV_TLSDESC_LOAD_LO12:
+  case R_RISCV_TLSDESC_ADD_LO12:
   case R_RISCV_TPREL_LO12_I:
   case R_RISCV_LO12_I: {
     uint64_t hi = (val + 0x800) >> 12;
@@ -513,29 +547,113 @@ void RISCV::relocate(uint8_t *loc, const Relocation &rel, uint64_t val) const {
     break;
 
   case R_RISCV_RELAX:
-    return; // Ignored (for now)
-
+    return;
+  case R_RISCV_TLSDESC:
+    // The addend is stored in the second word.
+    if (config->is64)
+      write64le(loc + 8, val);
+    else
+      write32le(loc + 4, val);
+    break;
   default:
     llvm_unreachable("unknown relocation");
   }
 }
 
+static void tlsdescToIe(uint8_t *loc, const Relocation &rel, uint64_t val) {
+  switch (rel.type) {
+  case R_RISCV_TLSDESC_HI20:
+  case R_RISCV_TLSDESC_LOAD_LO12:
+    write32le(loc, 0x00000013); // nop
+    return;
+  case R_RISCV_TLSDESC_ADD_LO12:
+    write32le(loc, utype(AUIPC, X_A0, hi20(val))); // auipc a0,<hi20>
+    return;
+  case R_RISCV_TLSDESC_CALL:
+    if (config->is64)
+      write32le(loc, itype(LD, X_A0, X_A0, lo12(val))); // ld a0,<lo12>(a0)
+    else
+      write32le(loc, itype(LW, X_A0, X_A0, lo12(val))); // lw a0,<lo12>(a0)
+    return;
+  default:
+    llvm_unreachable("unsupported relocation for TLSDESC to IE relaxation");
+  }
+}
+
+static void tlsdescToLe(uint8_t *loc, const Relocation &rel, uint64_t val) {
+  switch (rel.type) {
+  case R_RISCV_TLSDESC_HI20:
+  case R_RISCV_TLSDESC_LOAD_LO12:
+    write32le(loc, 0x00000013); // nop
+    return;
+  case R_RISCV_TLSDESC_ADD_LO12:
+    write32le(loc, utype(LUI, X_A0, hi20(val))); // lui a0,<hi20>
+    return;
+  case R_RISCV_TLSDESC_CALL:
+    if (isInt<12>(val))
+      write32le(loc, itype(ADDI, X_A0, 0, val)); // addi a0,zero,<lo12>
+    else
+      write32le(loc, itype(ADDI, X_A0, X_A0, lo12(val))); // addi a0,a0,<lo12>
+    return;
+  default:
+    llvm_unreachable("unsupported relocation for TLSDESC to LE relaxation");
+  }
+}
+
 void RISCV::relocateAlloc(InputSectionBase &sec, uint8_t *buf) const {
   uint64_t secAddr = sec.getOutputSection()->addr;
   if (auto *s = dyn_cast<InputSection>(&sec))
     secAddr += s->outSecOff;
   else if (auto *ehIn = dyn_cast<EhInputSection>(&sec))
     secAddr += ehIn->getParent()->outSecOff;
-  for (size_t i = 0, size = sec.relocs().size(); i != size; ++i) {
-    const Relocation &rel = sec.relocs()[i];
+  uint64_t tlsdescVal = 0;
+  bool isToIe = true;
+  const ArrayRef<Relocation> relocs = sec.relocs();
+  for (size_t i = 0, size = relocs.size(); i != size; ++i) {
+    const Relocation &rel = relocs[i];
     uint8_t *loc = buf + rel.offset;
-    const uint64_t val =
+    uint64_t val =
         sec.getRelocTargetVA(sec.file, rel.type, rel.addend,
                              secAddr + rel.offset, *rel.sym, rel.expr);
 
     switch (rel.expr) {
     case R_RELAX_HINT:
+      continue;
+    case R_TLSDESC_PC:
+      // For R_RISCV_TLSDESC_HI20, store &got(sym)-PC to be used by the
+      // following two instructions L[DW] and ADDI.
+      if (rel.type == R_RISCV_TLSDESC_HI20)
+        tlsdescVal = val;
+      else
+        val = tlsdescVal;
       break;
+    case R_RELAX_TLS_GD_TO_IE:
+      // Only R_RISCV_TLSDESC_HI20 reaches here. tlsdescVal will be finalized
+      // after we see R_RISCV_TLSDESC_ADD_LO12 in the R_RELAX_TLS_GD_TO_LE case.
+      // The net effect is that tlsdescVal will be smaller than `val` to take
+      // into account of NOP instructions (in the absence of R_RISCV_RELAX)
+      // before AUIPC.
+      tlsdescVal = val + rel.offset;
+      isToIe = true;
+      tlsdescToIe(loc, rel, val);
+      continue;
+    case R_RELAX_TLS_GD_TO_LE:
+      // See the comment in handleTlsRelocation. For TLSDESC=>IE,
+      // R_RISCV_TLSDESC_{LOAD_LO12,ADD_LO12,CALL} also reach here. If isToIe is
+      // true, this is actually TLSDESC=>IE optimization.
+      if (rel.type == R_RISCV_TLSDESC_HI20) {
+        tlsdescVal = val;
+        isToIe = false;
+      } else {
+        if (isToIe && rel.type == R_RISCV_TLSDESC_ADD_LO12)
+          tlsdescVal -= rel.offset;
+        val = tlsdescVal;
+      }
+      if (isToIe)
+        tlsdescToIe(loc, rel, val);
+      else
+        tlsdescToLe(loc, rel, val);
+      continue;
     case R_RISCV_LEB128:
       if (i + 1 < size) {
         const Relocation &rel1 = sec.relocs()[i + 1];
@@ -554,32 +672,12 @@ void RISCV::relocateAlloc(InputSectionBase &sec, uint8_t *buf) const {
                   ": R_RISCV_SET_ULEB128 not paired with R_RISCV_SUB_SET128");
       return;
     default:
-      relocate(loc, rel, val);
       break;
     }
+    relocate(loc, rel, val);
   }
 }
 
-namespace {
-struct SymbolAnchor {
-  uint64_t offset;
-  Defined *d;
-  bool end; // true for the anchor of st_value+st_size
-};
-} // namespace
-
-struct elf::RISCVRelaxAux {
-  // This records symbol start and end offsets which will be adjusted according
-  // to the nearest relocDeltas element.
-  SmallVector<SymbolAnchor, 0> anchors;
-  // For relocations[i], the actual offset is r_offset - (i ? relocDeltas[i-1] :
-  // 0).
-  std::unique_ptr<uint32_t[]> relocDeltas;
-  // For relocations[i], the actual type is relocTypes[i].
-  std::unique_ptr<RelType[]> relocTypes;
-  SmallVector<uint32_t, 0> writes;
-};
-
 static void initSymbolAnchors() {
   SmallVector<InputSection *, 0> storage;
   for (OutputSection *osec : outputSections) {
@@ -762,6 +860,14 @@ static bool relax(InputSection &sec) {
           sec.relocs()[i + 1].type == R_RISCV_RELAX)
         relaxHi20Lo12(sec, i, loc, r, remove);
       break;
+    case R_RISCV_TLSDESC_HI20:
+    case R_RISCV_TLSDESC_LOAD_LO12:
+      // For LE or IE optimization, AUIPC and L[DW] are converted to a removable
+      // NOP.
+      if (r.expr != R_TLSDESC_PC && i + 1 != sec.relocs().size() &&
+          sec.relocs()[i + 1].type == R_RISCV_RELAX)
+        remove = 4;
+      break;
     }
 
     // For all anchors whose offsets are <= r.offset, they are preceded by
diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp
index b6a317bc3b6d697..7e0cfc50605198e 100644
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -1274,26 +1274,31 @@ static unsigned handleTlsRelocation(RelType type, Symbol &sym,
 
   if (config->emachine == EM_MIPS)
     return handleMipsTlsRelocation(type, sym, c, offset, addend, expr);
+  bool isRISCV = config->emachine == EM_RISCV;
 
   if (oneof<R_AARCH64_TLSDESC_PAGE, R_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC,
             R_TLSDESC_GOTPLT>(expr) &&
       config->shared) {
+    // R_RISCV_TLSDESC_{LOAD_LO12_I,ADD_LO12_I,CALL} reference a label. Do not
+    // set NEEDS_TLSDESC on the label.
     if (expr != R_TLSDESC_CALL) {
-      sym.setFlags(NEEDS_TLSDESC);
+      if (!isRISCV || type == R_RISCV_TLSDESC_HI20)
+        sym.setFlags(NEEDS_TLSDESC);
       c.addReloc({expr, type, offset, addend, &sym});
     }
     return 1;
   }
 
   // ARM, Hexagon, LoongArch and RISC-V do not support GD/LD to IE/LE
-  // relaxation.
+  // optimizations.
+  // RISC-V supports TLSDESC to IE/LE optimizations.
   // For PPC64, if the file has missing R_PPC64_TLSGD/R_PPC64_TLSLD, disable
   // relaxation as well.
-  bool toExecRelax = !config->shared && config->emachine != EM_ARM &&
-                     config->emachine != EM_HEXAGON &&
-                     config->emachine != EM_LOONGARCH &&
-                     config->emachine != EM_RISCV &&
-                     !c.file->ppc64DisableTLSRelax;
+  bool toExecRelax =
+      !config->shared && config->emachine != EM_ARM &&
+      config->emachine != EM_HEXAGON && config->emachine != EM_LOONGARCH &&
+      !(isRISCV && expr != R_TLSDESC_PC && expr != R_TLSDESC_CALL) &&
+      !c.file->ppc64DisableTLSRelax;
 
   // If we are producing an executable and the symbol is non-preemptable, it
   // must be defined and the code sequence can be relaxed to use Local-Exec.
@@ -1347,8 +1352,12 @@ static unsigned handleTlsRelocation(RelType type, Symbol &sym,
       return 1;
     }
 
-    // Global-Dynamic relocs can be relaxed to Initial-Exec or Local-Exec
+    // Global-Dynamic/TLSDESC can be relaxed to Initial-Exec or Local-Exec
     // depending on the symbol being locally defined or not.
+    //
+    // R_RISCV_TLSDESC_{LOAD_LO12_I,ADD_LO12_I,CALL} reference a non-preemptible
+    // label, so the LE transition will be categorized as R_RELAX_TLS_GD_TO_LE.
+    // We fix the categorization in RISCV::relocateAlloc.
     if (sym.isPreemptible) {
       sym.setFlags(NEEDS_TLSGD_TO_IE);
       c.addReloc({target->adjustTlsExpr(type, R_RELAX_TLS_GD_TO_IE), type,
diff --git a/lld/test/ELF/riscv-tlsdesc-gd-mixed.s b/lld/test/ELF/riscv-tlsdesc-gd-mixed.s
new file mode 100644
index 000000000000000..c0e91593ed9686d
--- /dev/null
+++ b/lld/test/ELF/riscv-tlsdesc-gd-mixed.s
@@ -0,0 +1,26 @@
+# REQUIRES: riscv
+# RUN: llvm-mc -filetype=obj -triple=riscv64 %s -o %t.o
+# RUN: ld.lld -shared %t.o -o %t.so
+# RUN: llvm-readobj -r %t.so | FileCheck %s --check-prefix=RELA
+
+## Both TLSDESC and DTPMOD64/DTPREL64 should be present.
+# RELA:      .rela.dyn {
+# RELA-NEXT:   0x[[#%X,ADDR:]] R_RISCV_TLSDESC      a 0x0
+# RELA-NEXT:   0x[[#ADDR+16]]  R_RISCV_TLS_DTPMOD64 a 0x0
+# RELA-NEXT:   0x[[#ADDR+24]]  R_RISCV_TLS_DTPREL64 a 0x0
+# RELA-NEXT: }
+
+  la.tls.gd a0,a
+  call __tls_get_addr at plt
+
+.Ltlsdesc_hi0:
+  auipc a2, %tlsdesc_hi(a)
+  ld    a3, %tlsdesc_load_lo(.Ltlsdesc_hi0)(a2)
+  addi  a0, a2, %tlsdesc_add_lo(.Ltlsdesc_hi0)
+  jalr  t0, 0(a3), %tlsdesc_call(.Ltlsdesc_hi0)
+
+.section .tbss,"awT", at nobits
+.globl a
+.zero 8
+a:
+.zero 4
diff --git a/lld/test/ELF/riscv-tlsdesc-relax.s b/lld/test/ELF/riscv-tlsdesc-relax.s
new file mode 100644
index 000000000000000..54cfac810990f66
--- /dev/null
+++ b/lld/test/ELF/riscv-tlsdesc-relax.s
@@ -0,0 +1,125 @@
+# REQUIRES: riscv
+# RUN: rm -rf %t && split-file %s %t && cd %t
+# RUN: llvm-mc -filetype=obj -triple=riscv64 -mattr=+c,+relax a.s -o a.64.o
+# RUN: llvm-mc -filetype=obj -triple=riscv64 -mattr=+c,+relax c.s -o c.64.o
+# RUN: ld.lld -shared -soname=c.64.so c.64.o -o c.64.so
+
+# RUN: ld.lld -shared -z now a.64.o c.64.o -o a.64.so -z separate-code
+# RUN: llvm-objdump --no-show-raw-insn -M no-aliases -h -d a.64.so | FileCheck %s --check-prefix=GD64
+
+# RUN: ld.lld -e 0 -z now a.64.o c.64.o -o a.64.le -z separate-code
+# RUN: llvm-objdump --no-show-raw-insn -M no-aliases -h -d a.64.le | FileCheck %s --check-prefix=LE64
+
+# RUN: ld.lld -e 0 -z now a.64.o c.64.so -o a.64.ie -z separate-code
+# RUN: llvm-objdump --no-show-raw-insn -M no-aliases -h -d a.64.ie | FileCheck %s --check-prefix=IE64
+
+# GD64:      .got     00000018 00000000000020c0
+# GD64-LABEL: <_start>:
+# GD64-NEXT:         jal     {{.*}} <foo>
+# GD64-LABEL: <foo>:
+## &.got[c]-. = 0x20c0+8 - 0x1004 = 0x10c4
+# GD64:        1004: auipc   a2, 0x1
+# GD64-NEXT:         ld      a3, 0xc4(a2)
+# GD64-NEXT:         addi    a0, a2, 0xc4
+# GD64-NEXT:         jalr    t0, 0x0(a3)
+# GD64-NEXT:         c.add   a0, tp
+# GD64-NEXT:         jal     {{.*}} <foo>
+# GD64-NEXT:         auipc   a4, 0x1
+# GD64-NEXT:         ld      a5, 0xae(a4)
+# GD64-NEXT:         addi    a0, a4, 0xae
+# GD64-NEXT:         jalr    t0, 0x0(a5)
+# GD64-NEXT:         c.add   a0, tp
+
+# LE64-LABEL: <_start>:
+# LE64-NEXT:         jal     {{.*}} <foo>
+# LE64-LABEL: <foo>:
+# LE64-NEXT:  11004: lui     a0, 0x0
+# LE64-NEXT:         addi    a0, zero, 0xc
+# LE64-NEXT:         c.add   a0, tp
+# LE64-NEXT:         jal     {{.*}} <foo>
+# LE64-NEXT:         addi    zero, zero, 0x0
+# LE64-NEXT:         lui     a0, 0x0
+# LE64-NEXT:         addi    a0, zero, 0xc
+# LE64-NEXT:         c.add   a0, tp
+# LE64-NEXT:         addi    zero, zero, 0x0
+# LE64-NEXT:         lui     a0, 0x0
+# LE64-NEXT:         addi    a0, zero, 0xc
+# LE64-NEXT:         c.add   a0, tp
+
+# IE64:       .got     00000010 00000000000120e0
+# IE64-LABEL: <_start>:
+# IE64-NEXT:         jal     {{.*}} <foo>
+# IE64-LABEL: <foo>:
+## &.got[c]-. = 0x120e0+8 - 0x11004 = 0x10e4
+# IE64-NEXT:  11004: auipc   a0, 0x1
+# IE64-NEXT:         ld      a0, 0xe4(a0)
+# IE64-NEXT:         c.add   a0, tp
+# IE64-NEXT:         jal     {{.*}} <foo>
+# IE64-NEXT:         addi    zero, zero, 0x0
+## &.got[c]-. = 0x120e0+8 - 0x11016 = 0x10d2
+# IE64-NEXT:  11016: auipc   a0, 0x1
+# IE64-NEXT:         ld      a0, 0xd2(a0)
+# IE64-NEXT:         c.add   a0, tp
+# IE64-NEXT:         addi    zero, zero, 0x0
+## &.got[c]-. = 0x120e0+8 - 0x11024 = 0x10c4
+# IE64-NEXT:  11024: auipc   a0, 0x1
+# IE64-NEXT:         ld      a0, 0xc4(a0)
+# IE64-NEXT:         c.add   a0, tp
+
+#--- a.s
+.globl _start
+_start:
+.balign 16
+  call foo
+
+foo:
+.Ltlsdesc_hi0:
+.option norelax
+## All 4 instructions have an R_RISCV_RELAX.
+  auipc a2, %tlsdesc_hi(c)
+  .reloc .-4, R_RISCV_RELAX, 0
+  ld    a3, %tlsdesc_load_lo(.Ltlsdesc_hi0)(a2)
+  .reloc .-4, R_RISCV_RELAX, 0
+  addi  a0, a2, %tlsdesc_add_lo(.Ltlsdesc_hi0)
+  .reloc .-4, R_RISCV_RELAX, 0
+  jalr  t0, 0(a3), %tlsdesc_call(.Ltlsdesc_hi0)
+  .reloc .-4, R_RISCV_RELAX, 0
+  add   a0, a0, tp
+.option relax
+
+  call foo
+
+.Ltlsdesc_hi1:
+.option norelax
+## LD has an R_RISCV_RELAX.
+  auipc a4, %tlsdesc_hi(c)
+  ld    a5, %tlsdesc_load_lo(.Ltlsdesc_hi1)(a4)
+  .reloc .-4, R_RISCV_RELAX, 0
+  addi  a0, a4, %tlsdesc_add_lo(.Ltlsdesc_hi1)
+  jalr  t0, 0(a5), %tlsdesc_call(.Ltlsdesc_hi1)
+  add   a0, a0, tp
+.option relax
+
+.Ltlsdesc_hi2:
+.option norelax
+## AUIPC has an R_RISCV_RELAX.
+  auipc a6, %tlsdesc_hi(c)
+  .reloc .-4, R_RISCV_RELAX, 0
+  ld    a7, %tlsdesc_load_lo(.Ltlsdesc_hi2)(a6)
+  addi  a0, a6, %tlsdesc_add_lo(.Ltlsdesc_hi2)
+  jalr  t0, 0(a7), %tlsdesc_call(.Ltlsdesc_hi2)
+  add   a0, a0, tp
+.option relax
+
+.section .tbss
+.globl a
+.zero 8
+a:
+.zero 3
+b:
+.zero 1
+
+#--- c.s
+.tbss
+.globl c
+c: .zero 4
diff --git a/lld/test/ELF/riscv-tlsdesc.s b/lld/test/ELF/riscv-tlsdesc.s
new file mode 100644
index 000000000000000..1759c6cc25583ec
--- /dev/null
+++ b/lld/test/ELF/riscv-tlsdesc.s
@@ -0,0 +1,192 @@
+# REQUIRES: riscv
+# RUN: rm -rf %t && split-file %s %t && cd %t
+# RUN: llvm-mc -filetype=obj -triple=riscv64 a.s -o a.64.o
+# RUN: llvm-mc -filetype=obj -triple=riscv64 c.s -o c.64.o
+# RUN: ld.lld -shared -soname=c.64.so c.64.o -o c.64.so
+# RUN: llvm-mc -filetype=obj -triple=riscv32 --defsym ELF32=1 a.s -o a.32.o
+# RUN: llvm-mc -filetype=obj -triple=riscv32 --defsym ELF32=1 c.s -o c.32.o
+# RUN: ld.lld -shared -soname=c.32.so c.32.o -o c.32.so
+
+# RUN: ld.lld -shared -z now a.64.o c.64.o -o a.64.so
+# RUN: llvm-readobj -r -x .got a.64.so | FileCheck --check-prefix=GD64-RELA %s
+# RUN: llvm-objdump --no-show-raw-insn -M no-aliases -h -d a.64.so | FileCheck %s --check-prefix=GD64
+
+# RUN: ld.lld -shared -z now a.64.o c.64.o -o rel.64.so -z rel
+# RUN: llvm-readobj -r -x .got rel.64.so | FileCheck --check-prefix=GD64-REL %s
+
+# RUN: ld.lld -e 0 -z now a.64.o c.64.o -o a.64.le
+# RUN: llvm-readelf -r a.64.le | FileCheck --check-prefix=NOREL %s
+# RUN: llvm-objdump --no-show-raw-insn -M no-aliases -h -d a.64.le | FileCheck %s --check-prefix=LE64
+
+# RUN: ld.lld -e 0 -z now a.64.o c.64.so -o a.64.ie
+# RUN: llvm-readobj -r a.64.ie | FileCheck --check-prefix=IE64-RELA %s
+# RUN: llvm-objdump --no-show-raw-insn -M no-aliases -h -d a.64.ie | FileCheck %s --check-prefix=IE64
+
+## 32-bit code is mostly the same. We only test a few variants. The IE optimization uses the LW instruction.
+
+# RUN: ld.lld -shared -z now a.32.o c.32.o -o rel.32.so -z rel
+# RUN: llvm-readobj -r -x .got rel.32.so | FileCheck --check-prefix=GD32-REL %s
+# RUN: ld.lld -e 0 -z now a.32.o c.32.so -o a.32.ie
+# RUN: llvm-objdump --no-show-raw-insn -M no-aliases -h -d a.32.ie | FileCheck %s --check-prefix=IE32
+
+# GD64-RELA:      .rela.dyn {
+# GD64-RELA-NEXT:   0x2408 R_RISCV_TLSDESC - 0x7FF
+# GD64-RELA-NEXT:   0x23E8 R_RISCV_TLSDESC a 0x0
+# GD64-RELA-NEXT:   0x23F8 R_RISCV_TLSDESC c 0x0
+# GD64-RELA-NEXT: }
+# GD64-RELA:      Hex dump of section '.got':
+# GD64-RELA-NEXT: 0x000023e0 20230000 00000000 00000000 00000000 #
+# GD64-RELA-NEXT: 0x000023f0 00000000 00000000 00000000 00000000 .
+
+# GD64-REL:      .rel.dyn {
+# GD64-REL-NEXT:   0x23F0 R_RISCV_TLSDESC -
+# GD64-REL-NEXT:   0x23D0 R_RISCV_TLSDESC a
+# GD64-REL-NEXT:   0x23E0 R_RISCV_TLSDESC c
+# GD64-REL-NEXT: }
+# GD64-REL:      Hex dump of section '.got':
+# GD64-REL-NEXT: 0x000023c8 08230000 00000000 00000000 00000000 .
+# GD64-REL-NEXT: 0x000023d8 00000000 00000000 00000000 00000000 .
+# GD64-REL-NEXT: 0x000023e8 00000000 00000000 00000000 00000000 .
+# GD64-REL-NEXT: 0x000023f8 ff070000 00000000                   .
+
+# GD32-REL:      .rel.dyn {
+# GD32-REL-NEXT:   0x2274 R_RISCV_TLSDESC -
+# GD32-REL-NEXT:   0x2264 R_RISCV_TLSDESC a
+# GD32-REL-NEXT:   0x226C R_RISCV_TLSDESC c
+# GD32-REL-NEXT: }
+# GD32-REL:      Hex dump of section '.got':
+# GD32-REL-NEXT: 0x00002260 00220000 00000000 00000000 00000000 .
+# GD32-REL-NEXT: 0x00002270 00000000 00000000 ff070000          .
+
+# GD64:      .got     00000038 00000000000023e0
+
+## &.got[a]-. = 0x23e0+8 - 0x12e0 = 0x1108
+# GD64:        12e0: auipc   a0, 0x1
+# GD64-NEXT:         ld      a1, 0x108(a0)
+# GD64-NEXT:         addi    a0, a0, 0x108
+# GD64-NEXT:         jalr    t0, 0x0(a1)
+# GD64-NEXT:         add     a0, a0, tp
+
+## &.got[b]-. = 0x23e0+40 - 0x12f4 = 0x1114
+# GD64-NEXT:   12f4: auipc   a2, 0x1
+# GD64-NEXT:         ld      a3, 0x114(a2)
+# GD64-NEXT:         addi    a0, a2, 0x114
+# GD64-NEXT:         jalr    t0, 0x0(a3)
+# GD64-NEXT:         add     a0, a0, tp
+
+## &.got[c]-. = 0x23e0+24 - 0x1308 = 0x10f0
+# GD64-NEXT:   1308: auipc   a4, 0x1
+# GD64-NEXT:         ld      a5, 0xf0(a4)
+# GD64-NEXT:         addi    a0, a4, 0xf0
+# GD64-NEXT:         jalr    t0, 0x0(a5)
+# GD64-NEXT:         add     a0, a0, tp
+
+# NOREL: no relocations
+
+## st_value(a) = 8
+# LE64-LABEL: <.text>:
+# LE64-NEXT:         addi    zero, zero, 0x0
+# LE64-NEXT:         addi    zero, zero, 0x0
+# LE64-NEXT:         lui     a0, 0x0
+# LE64-NEXT:         addi    a0, zero, 0x8
+# LE64-NEXT:         add     a0, a0, tp
+## st_value(b) = 11
+# LE64-NEXT:         addi    zero, zero, 0x0
+# LE64-NEXT:         addi    zero, zero, 0x0
+# LE64-NEXT:         lui     a0, 0x0
+# LE64-NEXT:         addi    a0, zero, 0x7ff
+# LE64-NEXT:         add     a0, a0, tp
+## st_value(c) = 12
+# LE64-NEXT:         addi    zero, zero, 0x0
+# LE64-NEXT:         addi    zero, zero, 0x0
+# LE64-NEXT:         lui     a0, 0x1
+# LE64-NEXT:         addi    a0, a0, -0x800
+# LE64-NEXT:         add     a0, a0, tp
+
+# IE64-RELA:      .rela.dyn {
+# IE64-RELA-NEXT:   0x123B0 R_RISCV_TLS_TPREL64 c 0x0
+# IE64-RELA-NEXT: }
+
+# IE64:       .got     00000010 00000000000123a8
+
+## a and b are optimized to use LE. c is optimized to IE.
+# IE64-LABEL: <.text>:
+# IE64-NEXT:         addi    zero, zero, 0x0
+# IE64-NEXT:         addi    zero, zero, 0x0
+# IE64-NEXT:         lui     a0, 0x0
+# IE64-NEXT:         addi    a0, zero, 0x8
+# IE64-NEXT:         add     a0, a0, tp
+# IE64-NEXT:         addi    zero, zero, 0x0
+# IE64-NEXT:         addi    zero, zero, 0x0
+# IE64-NEXT:         lui     a0, 0x0
+# IE64-NEXT:         addi    a0, zero, 0x7ff
+# IE64-NEXT:         add     a0, a0, tp
+# IE64-NEXT:         addi    zero, zero, 0x0
+# IE64-NEXT:         addi    zero, zero, 0x0
+## &.got[c]-. = 0x123a8+8 - 0x112b8 = 0x10f8
+# IE64-NEXT:  112b8: auipc   a0, 0x1
+# IE64-NEXT:         ld      a0, 0xf8(a0)
+# IE64-NEXT:         add     a0, a0, tp
+
+# IE32:       .got     00000008 00012248
+
+# IE32-LABEL: <.text>:
+# IE32-NEXT:         addi    zero, zero, 0x0
+# IE32-NEXT:         addi    zero, zero, 0x0
+# IE32-NEXT:         lui     a0, 0x0
+# IE32-NEXT:         addi    a0, zero, 0x8
+# IE32-NEXT:         add     a0, a0, tp
+# IE32-NEXT:         addi    zero, zero, 0x0
+# IE32-NEXT:         addi    zero, zero, 0x0
+# IE32-NEXT:         lui     a0, 0x0
+# IE32-NEXT:         addi    a0, zero, 0x7ff
+# IE32-NEXT:         add     a0, a0, tp
+# IE32-NEXT:         addi    zero, zero, 0x0
+# IE32-NEXT:         addi    zero, zero, 0x0
+## &.got[c]-. = 0x12248+4 - 0x111cc = 0x1080
+# IE32-NEXT:  111cc: auipc   a0, 0x1
+# IE32-NEXT:         lw      a0, 0x80(a0)
+# IE32-NEXT:         add     a0, a0, tp
+
+#--- a.s
+.macro load dst, src
+.ifdef ELF32
+lw \dst, \src
+.else
+ld \dst, \src
+.endif
+.endm
+
+.Ltlsdesc_hi0:
+  auipc a0, %tlsdesc_hi(a)
+  load  a1, %tlsdesc_load_lo(.Ltlsdesc_hi0)(a0)
+  addi  a0, a0, %tlsdesc_add_lo(.Ltlsdesc_hi0)
+  jalr  t0, 0(a1), %tlsdesc_call(.Ltlsdesc_hi0)
+  add   a0, a0, tp
+
+.Ltlsdesc_hi1:
+  auipc a2, %tlsdesc_hi(b)
+  load  a3, %tlsdesc_load_lo(.Ltlsdesc_hi1)(a2)
+  addi  a0, a2, %tlsdesc_add_lo(.Ltlsdesc_hi1)
+  jalr  t0, 0(a3), %tlsdesc_call(.Ltlsdesc_hi1)
+  add   a0, a0, tp
+
+.Ltlsdesc_hi2:
+  auipc a4, %tlsdesc_hi(c)
+  load  a5, %tlsdesc_load_lo(.Ltlsdesc_hi2)(a4)
+  addi  a0, a4, %tlsdesc_add_lo(.Ltlsdesc_hi2)
+  jalr  t0, 0(a5), %tlsdesc_call(.Ltlsdesc_hi2)
+  add   a0, a0, tp
+
+.section .tbss
+.globl a
+.zero 8
+a:
+.zero 2039  ## Place b at 0x7ff
+b:
+.zero 1
+
+#--- c.s
+.tbss
+.globl c
+c: .zero 4



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