[lld] [lld][ELF] Support relax R_LARCH_{ALIGN, PCALA_{HI20,LO12}, GOT_PC_{HI20,LO12}} (PR #78692)

via llvm-commits llvm-commits at lists.llvm.org
Fri Jan 19 03:08:41 PST 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-lld

Author: Jinyang He (MQ-mengqing)

<details>
<summary>Changes</summary>

Refer to commit 6611d58f5bbc ("Relax R_RISCV_ALIGN"), we can relax R_LARCH_ALIGN by same way. Reuse `SymbolAnchor`, `RISCVRelaxAux` and `initSymbolAnchors` to simplify codes. As `riscvFinalizeRelax` is an arch-specific function, put it override on `TargetInfo::finalizeRelax`, so that LoongArch can override it, too.

1, The flow of relax R_LARCH_ALIGN is almost consistent with RISCV. The difference is that LoongArch only has 4-bytes NOP and all executable insn is 4-bytes aligned. So LoongArch not need rewrite NOP sequence. Alignment maxBytesEmit parameter is supported in psABI v2.30. For reliability, only one relax pass is supported in this patch.

2, Relax R_LARCH_GOT_PC_{HI20,LO12} to R_LARCH_PCALA_{HI20,LO12} if the sym is a local got. And it can perform the next relaxation rule.

3, Relax R_LARCH_PCALA_{HI20,LO12} to R_LARCH_PCREL20_S2 if the dest is 4-bytes aligned and (dest - pc) is a 22bits-simm.

---

Patch is 24.00 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/78692.diff


8 Files Affected:

- (modified) lld/ELF/Arch/LoongArch.cpp (+253-2) 
- (modified) lld/ELF/Arch/RISCV.cpp (+5-24) 
- (modified) lld/ELF/InputSection.cpp (+4-3) 
- (modified) lld/ELF/InputSection.h (+20-4) 
- (modified) lld/ELF/Target.h (+3) 
- (modified) lld/ELF/Writer.cpp (+2-2) 
- (added) lld/test/ELF/loongarch-relax-align.s (+137) 
- (added) lld/test/ELF/loongarch-relax-pcalas.s (+58) 


``````````diff
diff --git a/lld/ELF/Arch/LoongArch.cpp b/lld/ELF/Arch/LoongArch.cpp
index ab2ec5b447d000..235bd0f783d8e8 100644
--- a/lld/ELF/Arch/LoongArch.cpp
+++ b/lld/ELF/Arch/LoongArch.cpp
@@ -36,6 +36,8 @@ class LoongArch final : public TargetInfo {
   bool usesOnlyLowPageBits(RelType type) const override;
   void relocate(uint8_t *loc, const Relocation &rel,
                 uint64_t val) const override;
+  bool relaxOnce(int pass) const override;
+  void finalizeRelax(int passes) const override;
 };
 } // end anonymous namespace
 
@@ -48,6 +50,8 @@ enum Op {
   ADDI_W = 0x02800000,
   ADDI_D = 0x02c00000,
   ANDI = 0x03400000,
+  PCADDI = 0x18000000,
+  PCALAU12I = 0x1a000000,
   PCADDU12I = 0x1c000000,
   LD_W = 0x28800000,
   LD_D = 0x28c00000,
@@ -465,8 +469,9 @@ RelExpr LoongArch::getRelExpr(const RelType type, const Symbol &s,
   case R_LARCH_TLS_GD_HI20:
     return R_TLSGD_GOT;
   case R_LARCH_RELAX:
-    // LoongArch linker relaxation is not implemented yet.
-    return R_NONE;
+    return config->relax ? R_RELAX_HINT : R_NONE;
+  case R_LARCH_ALIGN:
+    return R_RELAX_HINT;
 
   // Other known relocs that are explicitly unimplemented:
   //
@@ -659,6 +664,252 @@ void LoongArch::relocate(uint8_t *loc, const Relocation &rel,
   }
 }
 
+// Relax R_LARCH_PCALA_{HI20,LO12}
+// pcalau12i+addi.{d,w} to pcaddi
+static void relaxPcalaAddi(const InputSection &sec, size_t i, uint64_t loc,
+                           Relocation &r, Relocation &rl, uint32_t &remove) {
+  const Symbol &sym = *r.sym;
+  const uint32_t pca = read64le(sec.content().data() + r.offset);
+  const uint32_t adi = read64le(sec.content().data() + rl.offset);
+  const uint32_t rd = pca & 0x1f;
+  const uint32_t op_addi = config->is64 ? ADDI_D : ADDI_W;
+  const uint64_t dest = sym.getVA() + r.addend;
+  const int64_t displace = dest - loc;
+
+  if (!(dest & 0x3) && isInt<22>(displace) && rd == (adi & 0x1f) &&
+      rd == ((adi >> 5) & 0x1f) && rl.offset == r.offset + 4 &&
+      (adi & 0xffc00000) == op_addi) {
+    sec.relaxAux->relocTypes[i] = R_LARCH_PCREL20_S2;
+    sec.relaxAux->relocTypes[i + 2] = R_LARCH_RELAX;
+    sec.relaxAux->writes.push_back(PCADDI | rd);
+    remove = 4;
+  }
+}
+
+// Relax R_LARCH_GOT_PC_{HI20,LO12}
+// pcalau12i+ld.{d,w} to pcalau12i+addi.{d,w} or pcaddi
+static void relaxPcalaLd(const InputSection &sec, size_t i, uint64_t loc,
+                         Relocation &r, Relocation &rl, uint32_t &remove) {
+  const Symbol &sym = *r.sym;
+  const uint32_t pca = read64le(sec.content().data() + r.offset);
+  const uint32_t ld = read64le(sec.content().data() + rl.offset);
+  const uint32_t rd = pca & 0x1f;
+  const uint32_t op_addi = config->is64 ? ADDI_D : ADDI_W;
+  const uint32_t op_ld = config->is64 ? LD_D : LD_W;
+  const uint64_t dest = sym.getVA() + r.addend;
+  const int64_t displace = dest - loc;
+
+  if (!sym.isLocal())
+    return;
+
+  if (rd != (ld & 0x1f) || rd != ((ld >> 5) & 0x1f) ||
+      rl.offset != r.offset + 4 || (ld & 0xffc00000) != op_ld)
+    return;
+
+  if (!(dest & 0x3) && isInt<22>(displace)) {
+    sec.relaxAux->relocTypes[i] = R_LARCH_PCREL20_S2;
+    sec.relaxAux->relocTypes[i + 2] = R_LARCH_RELAX;
+    sec.relaxAux->writes.push_back(PCADDI | rd);
+    remove = 4;
+  } else {
+    sec.relaxAux->relocTypes[i] = R_LARCH_PCALA_HI20;
+    sec.relaxAux->relocTypes[i + 2] = R_LARCH_PCALA_LO12;
+    sec.relaxAux->writes.push_back(PCALAU12I | rd);
+    sec.relaxAux->writes.push_back(op_addi | (rd << 5) | rd);
+  }
+}
+
+static bool relax(InputSection &sec) {
+  const uint64_t secAddr = sec.getVA();
+  auto &aux = *sec.relaxAux;
+  bool changed = false;
+  ArrayRef<SymbolAnchor> sa = ArrayRef(aux.anchors);
+  uint64_t delta = 0;
+
+  std::fill_n(aux.relocTypes.get(), sec.relocs().size(), R_LARCH_NONE);
+  aux.writes.clear();
+  for (auto [i, r] : llvm::enumerate(sec.relocs())) {
+    const uint64_t loc = secAddr + r.offset - delta;
+    uint32_t &cur = aux.relocDeltas[i], remove = 0;
+    switch (r.type) {
+    case R_LARCH_ALIGN: {
+      const uint64_t addend = r.sym->isUndefined() ? Log2_64(r.addend) + 1 : r.addend;
+      const uint64_t allBytes = (1 << (addend & 0xff)) - 4;
+      const uint64_t align = 1 << (addend & 0xff);
+      const uint64_t maxBytes = addend >> 8;
+      const uint64_t off = loc & (align - 1);
+      const uint64_t curBytes = off == 0 ? 0 : align - off;
+      // All bytes beyond the alignment boundary should be removed.
+      // If emit bytes more than max bytes to emit, remove all.
+      if (maxBytes != 0 && curBytes > maxBytes)
+        remove = allBytes;
+      else
+        remove = allBytes - curBytes;
+      assert(static_cast<int32_t>(remove) >= 0 &&
+             "R_LARCH_ALIGN needs expanding the content");
+      break;
+    }
+    case R_LARCH_PCALA_HI20:
+      if (i + 3 < sec.relocs().size() &&
+          sec.relocs()[i + 1].type == R_LARCH_RELAX &&
+          sec.relocs()[i + 2].type == R_LARCH_PCALA_LO12 &&
+          sec.relocs()[i + 3].type == R_LARCH_RELAX)
+        relaxPcalaAddi(sec, i, loc, r, sec.relocs()[i + 2], remove);
+      break;
+    case R_LARCH_GOT_PC_HI20:
+      if (i + 3 < sec.relocs().size() &&
+          sec.relocs()[i + 1].type == R_LARCH_RELAX &&
+          sec.relocs()[i + 2].type == R_LARCH_GOT_PC_LO12 &&
+          sec.relocs()[i + 3].type == R_LARCH_RELAX)
+        relaxPcalaLd(sec, i, loc, r, sec.relocs()[i + 2], remove);
+      break;
+    }
+
+    // For all anchors whose offsets are <= r.offset, they are preceded by
+    // the previous relocation whose `relocDeltas` value equals `delta`.
+    // Decrease their st_value and update their st_size.
+    for (; sa.size() && sa[0].offset <= r.offset; sa = sa.slice(1)) {
+      if (sa[0].end)
+        sa[0].d->size = sa[0].offset - delta - sa[0].d->value;
+      else
+        sa[0].d->value = sa[0].offset - delta;
+    }
+    delta += remove;
+    if (delta != cur) {
+      cur = delta;
+      changed = true;
+    }
+  }
+
+  for (const SymbolAnchor &a : sa) {
+    if (a.end)
+      a.d->size = a.offset - delta - a.d->value;
+    else
+      a.d->value = a.offset - delta;
+  }
+  // Inform assignAddresses that the size has changed.
+  if (!isUInt<32>(delta))
+    fatal("section size decrease is too large: " + Twine(delta));
+  sec.bytesDropped = delta;
+  return changed;
+}
+
+// When relaxing just R_LARCH_ALIGN, relocDeltas is usually changed only once in
+// the absence of a linker script. For call and load/store R_LARCH_RELAX, code
+// shrinkage may reduce displacement and make more relocations eligible for
+// relaxation. Code shrinkage may increase displacement to a call/load/store
+// target at a higher fixed address, invalidating an earlier relaxation. Any
+// change in section sizes can have cascading effect and require another
+// relaxation pass.
+bool LoongArch::relaxOnce(int pass) const {
+  if (config->relocatable)
+    return false;
+
+  // TODO Relax multiple times.
+  if (pass > 0)
+    return false;
+
+  initSymbolAnchors();
+  SmallVector<InputSection *, 0> storage;
+  bool changed = false;
+  for (OutputSection *osec : outputSections) {
+    if (!(osec->flags & SHF_EXECINSTR))
+      continue;
+    for (InputSection *sec : getInputSections(*osec, storage))
+      changed |= relax(*sec);
+  }
+  return changed;
+}
+
+void LoongArch::finalizeRelax(int passes) const {
+  SmallVector<InputSection *, 0> storage;
+  for (OutputSection *osec : outputSections) {
+    if (!(osec->flags & SHF_EXECINSTR))
+      continue;
+    for (InputSection *sec : getInputSections(*osec, storage)) {
+      RelaxAux &aux = *sec->relaxAux;
+      if (!aux.relocDeltas)
+        continue;
+
+      MutableArrayRef<Relocation> rels = sec->relocs();
+      ArrayRef<uint8_t> old = sec->content();
+      size_t newSize = old.size() - aux.relocDeltas[rels.size() - 1];
+      size_t writesIdx = 0;
+      uint8_t *p = context().bAlloc.Allocate<uint8_t>(newSize);
+      uint64_t offset = 0;
+      int64_t delta = 0;
+      sec->content_ = p;
+      sec->size = newSize;
+      sec->bytesDropped = 0;
+
+      // Update section content: remove NOPs for R_LARCH_ALIGN and rewrite
+      // instructions for relaxed relocations.
+      for (size_t i = 0, e = rels.size(); i != e; ++i) {
+        uint32_t remove = aux.relocDeltas[i] - delta;
+        delta = aux.relocDeltas[i];
+        if (remove == 0 && aux.relocTypes[i] == R_LARCH_NONE)
+          continue;
+
+        // Copy from last location to the current relocated location.
+        const Relocation &r = rels[i];
+        uint64_t size = r.offset - offset;
+
+        // The rel.type may be fixed to R_LARCH_RELAX and the instruction
+        // will be deleted, then cause size<0
+        if (remove == 0 && (int64_t)size < 0) {
+          assert(aux.relocTypes[i] == R_LARCH_RELAX && "Unexpected size");
+          continue;
+        }
+
+        memcpy(p, old.data() + offset, size);
+        p += size;
+
+        int64_t skip = 0;
+        if (RelType newType = aux.relocTypes[i]) {
+          switch (newType) {
+          case R_LARCH_RELAX:
+            // Indicate the relocation is ignored.
+            break;
+          case R_LARCH_PCREL20_S2:
+          case R_LARCH_PCALA_HI20:
+          case R_LARCH_PCALA_LO12:
+            skip = 4;
+            write32le(p, aux.writes[writesIdx++]);
+            break;
+          default:
+            llvm_unreachable("unsupported type");
+          }
+        }
+
+        p += skip;
+        offset = r.offset + skip + remove;
+      }
+      memcpy(p, old.data() + offset, old.size() - offset);
+
+      // Subtract the previous relocDeltas value from the relocation offset.
+      // For a pair of R_LARCH_XXX/R_LARCH_RELAX with the same offset, decrease
+      // their r_offset by the same delta.
+      delta = 0;
+      for (size_t i = 0, e = rels.size(); i != e;) {
+        uint64_t cur = rels[i].offset;
+        do {
+          rels[i].offset -= delta;
+          // Fix expr so that getRelocTargetVA will get update value.
+          if (aux.relocTypes[i] == R_LARCH_PCREL20_S2)
+            rels[i].expr = R_PC;
+          else if (aux.relocTypes[i] == R_LARCH_PCALA_HI20)
+            rels[i].expr = R_LOONGARCH_PAGE_PC;
+          else if (aux.relocTypes[i] == R_LARCH_PCALA_LO12)
+            rels[i].expr = R_ABS;
+          if (aux.relocTypes[i] != R_LARCH_NONE)
+            rels[i].type = aux.relocTypes[i];
+        } while (++i != e && rels[i].offset == cur);
+        delta = aux.relocDeltas[i - 1];
+      }
+    }
+  }
+}
+
 TargetInfo *elf::getLoongArchTargetInfo() {
   static LoongArch target;
   return ⌖
diff --git a/lld/ELF/Arch/RISCV.cpp b/lld/ELF/Arch/RISCV.cpp
index d7d3d3e4781497..4536236ff85e89 100644
--- a/lld/ELF/Arch/RISCV.cpp
+++ b/lld/ELF/Arch/RISCV.cpp
@@ -45,6 +45,7 @@ class RISCV final : public TargetInfo {
                 uint64_t val) const override;
   void relocateAlloc(InputSectionBase &sec, uint8_t *buf) const override;
   bool relaxOnce(int pass) const override;
+  void finalizeRelax(int passes) const override;
 };
 
 } // end anonymous namespace
@@ -560,33 +561,13 @@ void RISCV::relocateAlloc(InputSectionBase &sec, uint8_t *buf) const {
   }
 }
 
-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() {
+void elf::initSymbolAnchors() {
   SmallVector<InputSection *, 0> storage;
   for (OutputSection *osec : outputSections) {
     if (!(osec->flags & SHF_EXECINSTR))
       continue;
     for (InputSection *sec : getInputSections(*osec, storage)) {
-      sec->relaxAux = make<RISCVRelaxAux>();
+      sec->relaxAux = make<RelaxAux>();
       if (sec->relocs().size()) {
         sec->relaxAux->relocDeltas =
             std::make_unique<uint32_t[]>(sec->relocs().size());
@@ -819,7 +800,7 @@ bool RISCV::relaxOnce(int pass) const {
   return changed;
 }
 
-void elf::riscvFinalizeRelax(int passes) {
+void RISCV::finalizeRelax(int passes) const {
   llvm::TimeTraceScope timeScope("Finalize RISC-V relaxation");
   log("relaxation passes: " + Twine(passes));
   SmallVector<InputSection *, 0> storage;
@@ -827,7 +808,7 @@ void elf::riscvFinalizeRelax(int passes) {
     if (!(osec->flags & SHF_EXECINSTR))
       continue;
     for (InputSection *sec : getInputSections(*osec, storage)) {
-      RISCVRelaxAux &aux = *sec->relaxAux;
+      RelaxAux &aux = *sec->relaxAux;
       if (!aux.relocDeltas)
         continue;
 
diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index 586404643cc1fd..80421f124ecba7 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -352,9 +352,10 @@ InputSectionBase *InputSection::getRelocatedSection() const {
 
 template <class ELFT, class RelTy>
 void InputSection::copyRelocations(uint8_t *buf) {
-  if (config->relax && !config->relocatable && config->emachine == EM_RISCV) {
-    // On RISC-V, relaxation might change relocations: copy from internal ones
-    // that are updated by relaxation.
+  if (config->relax && !config->relocatable &&
+      (config->emachine == EM_RISCV || config->emachine == EM_LOONGARCH)) {
+    // On LoongArch and RISC-V, relaxation might change relocations: copy
+    // from internal ones that are updated by relaxation.
     InputSectionBase *sec = getRelocatedSection();
     copyRelocations<ELFT, RelTy>(buf, llvm::make_range(sec->relocations.begin(),
                                                        sec->relocations.end()));
diff --git a/lld/ELF/InputSection.h b/lld/ELF/InputSection.h
index fbaea57bd586b0..9fbe85fce1f24c 100644
--- a/lld/ELF/InputSection.h
+++ b/lld/ELF/InputSection.h
@@ -101,7 +101,23 @@ class SectionBase {
         link(link), info(info) {}
 };
 
-struct RISCVRelaxAux;
+struct SymbolAnchor {
+  uint64_t offset;
+  Defined *d;
+  bool end; // true for the anchor of st_value+st_size
+};
+
+struct RelaxAux {
+  // 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;
+};
 
 // This corresponds to a section of an input file.
 class InputSectionBase : public SectionBase {
@@ -225,9 +241,9 @@ class InputSectionBase : public SectionBase {
     // basic blocks.
     JumpInstrMod *jumpInstrMod = nullptr;
 
-    // Auxiliary information for RISC-V linker relaxation. RISC-V does not use
-    // jumpInstrMod.
-    RISCVRelaxAux *relaxAux;
+    // Auxiliary information for RISC-V and LoongArch linker relaxation.
+    // RISC-V and LoongArch does not use jumpInstrMod.
+    RelaxAux *relaxAux;
 
     // The compressed content size when `compressed` is true.
     size_t compressedSize;
diff --git a/lld/ELF/Target.h b/lld/ELF/Target.h
index ab6b6b9c013ba3..ed00e81c0e6c81 100644
--- a/lld/ELF/Target.h
+++ b/lld/ELF/Target.h
@@ -95,6 +95,8 @@ class TargetInfo {
 
   // Do a linker relaxation pass and return true if we changed something.
   virtual bool relaxOnce(int pass) const { return false; }
+  // Do finalize relaxation after collecting relaxation infos.
+  virtual void finalizeRelax(int passes) const {}
 
   virtual void applyJumpInstrMod(uint8_t *loc, JumpModType type,
                                  JumpModType val) const {}
@@ -236,6 +238,7 @@ void addArmSyntheticSectionMappingSymbol(Defined *);
 void sortArmMappingSymbols();
 void convertArmInstructionstoBE8(InputSection *sec, uint8_t *buf);
 void createTaggedSymbols(const SmallVector<ELFFileBase *, 0> &files);
+void initSymbolAnchors();
 
 LLVM_LIBRARY_VISIBILITY extern const TargetInfo *target;
 TargetInfo *getTarget();
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index dfec5e07301a74..e2d83f0122b0b8 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -1750,8 +1750,8 @@ template <class ELFT> void Writer<ELFT>::finalizeAddressDependentContent() {
       }
     }
   }
-  if (!config->relocatable && config->emachine == EM_RISCV)
-    riscvFinalizeRelax(pass);
+  if (!config->relocatable)
+    target->finalizeRelax(pass);
 
   if (config->relocatable)
     for (OutputSection *sec : outputSections)
diff --git a/lld/test/ELF/loongarch-relax-align.s b/lld/test/ELF/loongarch-relax-align.s
new file mode 100644
index 00000000000000..19588b5b21cb98
--- /dev/null
+++ b/lld/test/ELF/loongarch-relax-align.s
@@ -0,0 +1,137 @@
+# REQUIRES: loongarch
+
+# RUN: llvm-mc --filetype=obj --triple=loongarch32 --mattr=+relax %s -o %t.32.o
+# RUN: llvm-mc --filetype=obj --triple=loongarch64 --mattr=+relax %s -o %t.64.o
+# RUN: ld.lld --section-start=.text=0x10000 --section-start=.text2=0x20000 -e 0 %t.32.o -o %t.32
+# RUN: ld.lld --section-start=.text=0x10000 --section-start=.text2=0x20000 -e 0 %t.64.o -o %t.64
+# RUN: ld.lld --section-start=.text=0x10000 --section-start=.text2=0x20000 -e 0 %t.32.o --no-relax -o %t.32n
+# RUN: ld.lld --section-start=.text=0x10000 --section-start=.text2=0x20000 -e 0 %t.64.o --no-relax -o %t.64n
+# RUN: llvm-objdump -td --no-show-raw-insn %t.32 | FileCheck %s --check-prefixes=CHECK,RELAX
+# RUN: llvm-objdump -td --no-show-raw-insn %t.64 | FileCheck %s --check-prefixes=CHECK,RELAX
+# RUN: llvm-objdump -td --no-show-raw-insn %t.32n | FileCheck %s --check-prefixes=CHECK,NOREL
+# RUN: llvm-objdump -td --no-show-raw-insn %t.64n | FileCheck %s --check-prefixes=CHECK,NOREL
+
+## Test the R_LARCH_ALIGN without symbol index.
+# RUN: llvm-mc --filetype=obj --triple=loongarch64 --mattr=+relax %s -o %t.o64.o --defsym=old=1
+# RUN: ld.lld --section-start=.text=0x10000 --section-start=.text2=0x20000 -e 0 %t.o64.o -o %t.o64
+# RUN: ld.lld --section-start=.text=0x10000 --section-start=.text2=0x20000 -e 0 %t.o64.o --no-relax -o %t.o64n
+# RUN: llvm-objdump -td --no-show-raw-insn %t.o64 | FileCheck %s --check-prefixes=CHECK,RELAX
+# RUN: llvm-objdump -td --no-show-raw-insn %t.o64n | FileCheck %s --check-prefixes=CHECK,NOREL
+
+## -r keeps section contents unchanged.
+# RUN: ld.lld -r %t.64.o -o %t.64.r
+# RUN: llvm-objdump -dr --no-show-raw-insn %t.64.r | FileCheck %s --check-prefix=CHECKR
+
+# RELAX-DAG: {{0*}}10000 l .text  {{0*}}34 .Ltext_start
+# RELAX-DAG: {{0*}}1002c l .text  {{0*}}08 .L1
+# RELAX-DAG: {{0*}}10030 l .text  {{0*}}04 .L2
+# RELAX-DAG: {{0*}}20000 l .text2 {{0*}}14 .Ltext2_start
+# NOREL-DAG: {{0*}}10000 l .text  {{0*}}44 .Ltext_start
+# NOREL-DAG: {{0*}}10038 l .text  {{0*}}0c .L1
+# NOREL-DAG: {{0*}}10040 l .text  {{0*}}04 .L2
+# NOREL-DAG: {{0*}}20000 l .text2 {{0*}}14 .Ltext2_start
+
+# CHECK:      <.Ltext_start>:
+# CHECK-NEXT:    10000:      break 1
+# CHECK-NEXT:    10004:      break 2
+# CHECK-NEXT:    10008:      nop
+# CHECK-NEXT:    1000c:      nop
+# CHECK-NEXT:    10010:      break 3
+# CHECK-NEXT:    10014:      break 4
+# CHECK-NEXT:    10018:      nop
+# CHECK-NEXT:    1001c:      nop
+# RELAX-NEXT:    10020:      pcaddi $zero, -8
+# RELAX-NEXT:    10024:      pcaddi $zero, 2
+# RELAX-NEXT:    10028:      pcaddi $zero, 2
+# NOREL-NEXT:    10020:      pcalau12i     $zero, 0
+# NOREL-NEXT:    10024:      addi.{{[dw]}} $zero, $zero, 0
+# NOREL-NEXT:    10028:      pcalau12i     $zero, 0
+# NOREL-NEXT:    1002c:      addi.{{[dw]}} $zero, $zero, 56
+# NOREL-NEXT:    10030:      pcalau12i     $zero, 0
+# NOREL-NEXT:    10034:      addi.{{[dw]}} $zero, $zero, 64
+# CHECK-EMPTY:
+# CHECK-NEXT: <.L1>:
+# RELAX-NEXT:    1002c:      nop
+# NOREL-NEXT:    10038:      nop
+# NOREL-NEXT:    1003c:      nop
+# CHECK-EMPTY:
+# CHECK-NEXT: <.L2>:
+# CHECK-NEXT:    break 5
+
+# CHECK:      <.Ltext2_start>:
+# RELAX-NEXT:    20000:     pcaddi $zero, 0
+# RELAX-NEXT:    20004:     nop
+# NOREL-NEXT:    20000:     pcalau12i     $zero, 0
+# NOREL-NEXT:    20004:     addi.{{[dw]}} $zero, $zero, 0
+# CHECK-NEXT:    20008:     nop
+...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/78692


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