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PR for llvm/llvm-project#79507 #79509

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resolves #79507

Support
R_RISCV_TLSDESC_HI20/R_RISCV_TLSDESC_LOAD_LO12/R_RISCV_TLSDESC_ADD_LO12/R_RISCV_TLSDESC_CALL.
LOAD_LO12/ADD_LO12/CALL relocations reference a label at the HI20
location, which requires special handling. We save the value of HI20 to
be reused. Two interleaved TLSDESC code sequences, which compilers do
not generate, are unsupported.

For -no-pie/-pie links, TLSDESC to initial-exec or local-exec
optimizations are eligible. Implement the relevant hooks
(R_RELAX_TLS_GD_TO_LE, R_RELAX_TLS_GD_TO_IE): the first two instructions
are converted to NOP while the latter two are converted to a GOT load or
a lui+addi.

The first two instructions, which would be converted to NOP, are removed
instead in the presence of relaxation. Relaxation is eligible as long as
the R_RISCV_TLSDESC_HI20 relocation has a pairing R_RISCV_RELAX,
regardless of whether the following instructions have a R_RISCV_RELAX.
In addition, for the TLSDESC to LE optimization (`lui a0,<hi20>; addi a0,a0,<lo12>`),
`lui` can be removed (i.e. use the short form) if hi20 is 0.

```
// TLSDESC to LE/IE optimization
.Ltlsdesc_hi2:
  auipc a4, %tlsdesc_hi(c)                      # if relax: remove; otherwise, NOP
  load  a5, %tlsdesc_load_lo(.Ltlsdesc_hi2)(a4) # if relax: remove; otherwise, NOP
  addi  a0, a4, %tlsdesc_add_lo(.Ltlsdesc_hi2)  # if LE && !hi20 {if relax: remove; otherwise, NOP}
  jalr  t0, 0(a5), %tlsdesc_call(.Ltlsdesc_hi2)
  add   a0, a0, tp
```

The implementation carefully ensures that an instruction unrelated to
the current TLSDESC code sequence, if immediately follows a removable
instruction (HI20 or LOAD_LO12 OR (LE-specific) ADD_LO12), is not
converted to NOP.

* `riscv64-tlsdesc.s` is inspired by `i386-tlsdesc-gd.s` (https://reviews.llvm.org/D112582).
* `riscv64-tlsdesc-relax.s` tests linker relaxation.
* `riscv-tlsdesc-gd-mixed.s` is inspired by `x86-64-tlsdesc-gd-mixed.s` (https://reviews.llvm.org/D116900).

Link: riscv-non-isa/riscv-elf-psabi-doc#373

Reviewed By: ilovepi

Pull Request: llvm#79239

(cherry picked from commit 1117fdd)
@llvmbot
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llvmbot commented Jan 25, 2024

@llvm/pr-subscribers-lld

@llvm/pr-subscribers-lld-elf

Author: None (github-actions[bot])

Changes

resolves llvm/llvm-project#79507


Patch is 32.20 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/79509.diff

5 Files Affected:

  • (modified) lld/ELF/Arch/RISCV.cpp (+164-35)
  • (modified) lld/ELF/Relocations.cpp (+30-20)
  • (added) lld/test/ELF/riscv-tlsdesc-gd-mixed.s (+26)
  • (added) lld/test/ELF/riscv-tlsdesc-relax.s (+189)
  • (added) lld/test/ELF/riscv-tlsdesc.s (+194)
diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp
index d7d3d3e47814971..8ce92b4badfbd7e 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;
@@ -513,32 +547,133 @@ 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 bool relaxable(ArrayRef<Relocation> relocs, size_t i) {
+  return i + 1 != relocs.size() && relocs[i + 1].type == R_RISCV_RELAX;
+}
+
+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
+    break;
+  case R_RISCV_TLSDESC_ADD_LO12:
+    write32le(loc, utype(AUIPC, X_A0, hi20(val))); // auipc a0,<hi20>
+    break;
+  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)
+    break;
+  default:
+    llvm_unreachable("unsupported relocation for TLSDESC to IE");
+  }
+}
+
+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:
+    if (isInt<12>(val))
+      write32le(loc, 0x00000013); // nop
+    else
+      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");
+  }
+}
+
 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 tlsdescRelax = false, isToLe = false;
+  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;
+      isToLe = false;
+      tlsdescRelax = relaxable(relocs, i);
+      if (!tlsdescRelax)
+        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;
+        isToLe = true;
+        tlsdescRelax = relaxable(relocs, i);
+      } else {
+        if (!isToLe && rel.type == R_RISCV_TLSDESC_ADD_LO12)
+          tlsdescVal -= rel.offset;
+        val = tlsdescVal;
+      }
+      // When NOP conversion is eligible and relaxation applies, don't write a
+      // NOP in case an unrelated instruction follows the current instruction.
+      if (tlsdescRelax &&
+          (rel.type == R_RISCV_TLSDESC_HI20 ||
+           rel.type == R_RISCV_TLSDESC_LOAD_LO12 ||
+           (rel.type == R_RISCV_TLSDESC_ADD_LO12 && isToLe && !hi20(val))))
+        continue;
+      if (isToLe)
+        tlsdescToLe(loc, rel, val);
+      else
+        tlsdescToIe(loc, rel, val);
+      continue;
     case R_RISCV_LEB128:
       if (i + 1 < size) {
-        const Relocation &rel1 = sec.relocs()[i + 1];
+        const Relocation &rel1 = relocs[i + 1];
         if (rel.type == R_RISCV_SET_ULEB128 &&
             rel1.type == R_RISCV_SUB_ULEB128 && rel.offset == rel1.offset) {
           auto val = rel.sym->getVA(rel.addend) - rel1.sym->getVA(rel1.addend);
@@ -554,32 +689,12 @@ 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) {
@@ -715,14 +830,16 @@ static void relaxHi20Lo12(const InputSection &sec, size_t i, uint64_t loc,
 
 static bool relax(InputSection &sec) {
   const uint64_t secAddr = sec.getVA();
+  const MutableArrayRef<Relocation> relocs = sec.relocs();
   auto &aux = *sec.relaxAux;
   bool changed = false;
   ArrayRef<SymbolAnchor> sa = ArrayRef(aux.anchors);
   uint64_t delta = 0;
+  bool tlsdescRelax = false, toLeShortForm = false;
 
-  std::fill_n(aux.relocTypes.get(), sec.relocs().size(), R_RISCV_NONE);
+  std::fill_n(aux.relocTypes.get(), relocs.size(), R_RISCV_NONE);
   aux.writes.clear();
-  for (auto [i, r] : llvm::enumerate(sec.relocs())) {
+  for (auto [i, r] : llvm::enumerate(relocs)) {
     const uint64_t loc = secAddr + r.offset - delta;
     uint32_t &cur = aux.relocDeltas[i], remove = 0;
     switch (r.type) {
@@ -743,25 +860,37 @@ static bool relax(InputSection &sec) {
     }
     case R_RISCV_CALL:
     case R_RISCV_CALL_PLT:
-      if (i + 1 != sec.relocs().size() &&
-          sec.relocs()[i + 1].type == R_RISCV_RELAX)
+      if (relaxable(relocs, i))
         relaxCall(sec, i, loc, r, remove);
       break;
     case R_RISCV_TPREL_HI20:
     case R_RISCV_TPREL_ADD:
     case R_RISCV_TPREL_LO12_I:
     case R_RISCV_TPREL_LO12_S:
-      if (i + 1 != sec.relocs().size() &&
-          sec.relocs()[i + 1].type == R_RISCV_RELAX)
+      if (relaxable(relocs, i))
         relaxTlsLe(sec, i, loc, r, remove);
       break;
     case R_RISCV_HI20:
     case R_RISCV_LO12_I:
     case R_RISCV_LO12_S:
-      if (i + 1 != sec.relocs().size() &&
-          sec.relocs()[i + 1].type == R_RISCV_RELAX)
+      if (relaxable(relocs, i))
         relaxHi20Lo12(sec, i, loc, r, remove);
       break;
+    case R_RISCV_TLSDESC_HI20:
+      // For TLSDESC=>LE, we can use the short form if hi20 is zero.
+      tlsdescRelax = relaxable(relocs, i);
+      toLeShortForm = tlsdescRelax && r.expr == R_RELAX_TLS_GD_TO_LE &&
+                      !hi20(r.sym->getVA(r.addend));
+      [[fallthrough]];
+    case R_RISCV_TLSDESC_LOAD_LO12:
+      // For TLSDESC=>LE/IE, AUIPC and L[DW] are removed if relaxable.
+      if (tlsdescRelax && r.expr != R_TLSDESC_PC)
+        remove = 4;
+      break;
+    case R_RISCV_TLSDESC_ADD_LO12:
+      if (toLeShortForm)
+        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..79c8230724ade7b 100644
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -1274,29 +1274,34 @@ 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,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;
+  // optimization as well.
+  bool execOptimize =
+      !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.
+  // must be defined and the code sequence can be optimized to use Local-Exec.
   //
   // ARM and RISC-V do not support any relaxations for TLS relocations, however,
   // we can omit the DTPMOD dynamic relocations and resolve them at link time
@@ -1309,8 +1314,8 @@ static unsigned handleTlsRelocation(RelType type, Symbol &sym,
   // module index, with a special value of 0 for the current module. GOT[e1] is
   // unused. There only needs to be one module index entry.
   if (oneof<R_TLSLD_GOT, R_TLSLD_GOTPLT, R_TLSLD_PC, R_TLSLD_HINT>(expr)) {
-    // Local-Dynamic relocs can be relaxed to Local-Exec.
-    if (toExecRelax) {
+    // Local-Dynamic relocs can be optimized to Local-Exec.
+    if (execOptimize) {
       c.addReloc({target->adjustTlsExpr(type, R_RELAX_TLS_LD_TO_LE), type,
                   offset, addend, &sym});
       return target->getTlsGdRelaxSkip(type);
@@ -1322,16 +1327,17 @@ static unsigned handleTlsRelocation(RelType type, Symbol &sym,
     return 1;
   }
 
-  // Local-Dynamic relocs can be relaxed to Local-Exec.
+  // Local-Dynamic relocs can be optimized to Local-Exec.
   if (expr == R_DTPREL) {
-    if (toExecRelax)
+    if (execOptimize)
       expr = target->adjustTlsExpr(type, R_RELAX_TLS_LD_TO_LE);
     c.addReloc({expr, type, offset, addend, &sym});
     return 1;
   }
 
   // Local-Dynamic sequence where offset of tls variable relative to dynamic
-  // thread pointer is stored in the got. This cannot be relaxed to Local-Exec.
+  // thread pointer is stored in the got. This cannot be optimized to
+  // Local-Exec.
   if (expr == R_TLSLD_GOT_OFF) {
     sym.setFlags(NEEDS_GOT_DTPREL);
     c.addReloc({expr, type, offset, addend, &sym});
@@ -1341,14 +1347,18 @@ static unsigned handleTlsRelocation(RelType type, Symbol &sym,
   if (oneof<R_AARCH64_TLSDESC_PAGE, R_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC,
             R_TLSDESC_GOTPLT, R_TLSGD_GOT, R_TLSGD_GOTPLT, R_TLSGD_PC,
             R_LOONGARCH_TLSGD_PAGE_PC>(expr)) {
-    if (!toExecRelax) {
+    if (!execOptimize) {
       sym.setFlags(NEEDS_TLSGD);
       c.addReloc({expr, type, offset, addend, &sym});
       return 1;
     }
 
-    // Global-Dynamic relocs can be relaxed to Initial-Exec or Local-Exec
+    // Global-Dynamic/TLSDESC can be optimized to Initial-Exec or Local-Exec
     // depending on the symbol being locally defined or not.
+    //
+    // R_RISCV_TLSDESC_{LOAD_LO12,ADD_LO12_I,CALL} reference a non-preemptible
+    // label, so the LE optimization 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,
@@ -1363,9 +1373,9 @@ static unsigned handleTlsRelocation(RelType type, Symbol &sym,
   if (oneof<R_GOT, R_GOTPLT, R_GOT_PC, R_AARCH64_GOT_PAGE_PC,
             R_LOONGARCH_GOT_PAGE_PC, R_GOT_OFF, R_TLSIE_HINT>(expr)) {
     ctx.hasTlsIe.store(true, std::memory_order_relaxed);
-    // Initial-Exec relocs can be relaxed to Local-Exec if the symbol is locally
-    // defined.
-    if (toExecRelax && isLocalInExecutable) {
+    // Initial-Exec relocs can be optimized to Local-Exec if the symbol is
+    // locally defined.
+    if (execOptimize && isLocalInExecutable) {
       c.addReloc({R_RELAX_TLS_IE_TO_LE, type, offset, addend, &sym});
     } else if (expr != R_TLSIE_HINT) {
       sym.setFlags(NEEDS_TLSIE);
@@ -1463,7 +1473,7 @@ template <class ELFT, class RelTy> void RelocationScanner::scanOne(RelTy *&i) {
     in.got->hasGotOffRel.store(true, std::memory_order_relaxed);
   }
 
-  // Process TLS relocations, including relaxing TLS relocations. Note that
+  // Process TLS relocations, including TLS optimizations. Note that
   // R_TPREL and R_TPREL_NEG relocations are resolved in processAux.
   if (sym.isTls()) {
     if (unsigned processed =
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@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",@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..fb24317e6535cae
--- /dev/null
+++ b/lld/test/ELF/riscv-tlsdesc-relax.s
@@ -0,0 +1,189 @@
+# REQUIRES: riscv
+# RUN: rm -rf %t && split-file %s %t && cd %t
+# RUN: llvm-mc -filetype=obj -triple=riscv64 --defsym PAD=0 -mattr=+c,+relax a.s -o a.64.o
+# RUN: llvm-mc -filetype=obj -triple=riscv64 --defsym PAD=5000 -mattr=+c,+relax a.s -o aa.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
+
+## Test the TLSDESC to LE optimization. Also check --emit-relocs.
+# RUN: ld.lld -e 0 -z now a.64.o c.64.o -o a.64.le -z separate-code --emit-relocs
+# RUN: llvm-objdump --no-show-raw-insn -M no-aliases -hdr a.64.le | FileCheck %s --check-prefix=LE64
+# RUN: ld.lld -e 0 -z now aa.64.o c.64.o -o aa.64.le -z separate-code
+# RUN: llvm-objdump --no-show-raw-insn -M no-aliases -h -d aa.64.le | FileCheck %s --check-prefix=LE64A
+
+## Test the TLSDESC to IE optimization.
+# 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:         c.add   a7, a7
+# GD64-NEXT:         ld      a3, 0xc4(a2)
+# GD64-NEXT:         c.add   a7, a7
+# GD64-NEXT:         addi    a0, a2, 0xc4
+# GD64-NEXT:         c.add   a7, a7
+# GD64-NEXT:         jalr    t0, 0x0(a3)
+# GD64-NEXT:         c.add   a0, tp
+# GD64-NEXT:         jal     {{.*}} <foo>
+## &.got[c]-. = 0x20c0+8 - 0x1020 = 0x10a8
+# GD64-NEXT:   1020: auipc   a4, 0x1
+# GD64-NEXT:         ld      a5, 0xa8(a4)
+# GD64-NEXT:         addi    a0, a4, 0xa8
+# GD64-NEXT:         jalr    t0, 0x0(a5)
+# GD64-NEXT:         c.add   a0, tp
+## &.got[c]-. = 0x20c0+8 - 0x1032 = 0x1096
+# GD64-NEXT:   1032: auipc   a6, 0x1
+# GD64-NEXT:         ld      a7,...
[truncated]

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Merged: e2521ea 3d02473 e9d99e5

@tstellar tstellar closed this Jan 27, 2024
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