1 files changed, 126 insertions, 0 deletions
diff --git a/lld/ELF/RelocScan.h b/lld/ELF/RelocScan.h
new file mode 100644
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--- /dev/null
+++ b/lld/ELF/RelocScan.h
@@ -0,0 +1,126 @@
+//===------------------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_ELF_RELOCSCAN_H
+#define LLD_ELF_RELOCSCAN_H
+
+#include "Config.h"
+#include "InputFiles.h"
+#include "InputSection.h"
+#include "Relocations.h"
+#include "SyntheticSections.h"
+#include "Target.h"
+
+using namespace llvm;
+using namespace llvm::ELF;
+using namespace llvm::object;
+
+namespace lld::elf {
+
+// Build a bitmask with one bit set for each 64 subset of RelExpr.
+inline constexpr uint64_t buildMask() { return 0; }
+
+template <typename... Tails>
+inline constexpr uint64_t buildMask(int head, Tails... tails) {
+  return (0 <= head && head < 64 ? uint64_t(1) << head : 0) |
+         buildMask(tails...);
+}
+
+// Return true if `Expr` is one of `Exprs`.
+// There are more than 64 but less than 128 RelExprs, so we divide the set of
+// exprs into [0, 64) and [64, 128) and represent each range as a constant
+// 64-bit mask. Then we decide which mask to test depending on the value of
+// expr and use a simple shift and bitwise-and to test for membership.
+template <RelExpr... Exprs> bool oneof(RelExpr expr) {
+  assert(0 <= expr && (int)expr < 128 &&
+         "RelExpr is too large for 128-bit mask!");
+
+  if (expr >= 64)
+    return (uint64_t(1) << (expr - 64)) & buildMask((Exprs - 64)...);
+  return (uint64_t(1) << expr) & buildMask(Exprs...);
+}
+
+// This class encapsulates states needed to scan relocations for one
+// InputSectionBase.
+class RelocScan {
+public:
+  Ctx &ctx;
+  InputSectionBase *sec;
+
+  RelocScan(Ctx &ctx, InputSectionBase *sec = nullptr) : ctx(ctx), sec(sec) {}
+  template <class ELFT, class RelTy>
+  void scan(typename Relocs<RelTy>::const_iterator &i, RelType type,
+            int64_t addend);
+  void scanEhSection(EhInputSection &s);
+
+  template <class ELFT, class RelTy>
+  int64_t getAddend(const RelTy &r, RelType type);
+  bool maybeReportUndefined(Undefined &sym, uint64_t offset);
+  bool checkTlsLe(uint64_t offset, Symbol &sym, RelType type);
+  bool isStaticLinkTimeConstant(RelExpr e, RelType type, const Symbol &sym,
+                                uint64_t relOff) const;
+  void process(RelExpr expr, RelType type, uint64_t offset, Symbol &sym,
+               int64_t addend) const;
+  unsigned handleTlsRelocation(RelExpr expr, RelType type, uint64_t offset,
+                               Symbol &sym, int64_t addend);
+};
+
+template <class ELFT, class RelTy>
+int64_t RelocScan::getAddend(const RelTy &r, RelType type) {
+  return RelTy::HasAddend ? elf::getAddend<ELFT>(r)
+                          : ctx.target->getImplicitAddend(
+                                sec->content().data() + r.r_offset, type);
+}
+
+template <class ELFT, class RelTy>
+void RelocScan::scan(typename Relocs<RelTy>::const_iterator &it, RelType type,
+                     int64_t addend) {
+  const RelTy &rel = *it;
+  uint32_t symIdx = rel.getSymbol(false);
+  Symbol &sym = sec->getFile<ELFT>()->getSymbol(symIdx);
+  uint64_t offset = rel.r_offset;
+  RelExpr expr =
+      ctx.target->getRelExpr(type, sym, sec->content().data() + offset);
+
+  // Ignore R_*_NONE and other marker relocations.
+  if (expr == R_NONE)
+    return;
+
+  // Error if the target symbol is undefined. Symbol index 0 may be used by
+  // marker relocations, e.g. R_*_NONE and R_ARM_V4BX. Don't error on them.
+  if (sym.isUndefined() && symIdx != 0 &&
+      maybeReportUndefined(cast<Undefined>(sym), offset))
+    return;
+
+  // Ensure GOT or GOTPLT is created for relocations that reference their base
+  // addresses without directly creating entries.
+  if (oneof<R_GOTPLTONLY_PC, R_GOTPLTREL, R_GOTPLT, R_PLT_GOTPLT,
+            R_TLSDESC_GOTPLT, R_TLSGD_GOTPLT>(expr)) {
+    ctx.in.gotPlt->hasGotPltOffRel.store(true, std::memory_order_relaxed);
+  } else if (oneof<R_GOTONLY_PC, R_GOTREL, RE_PPC32_PLTREL>(expr)) {
+    ctx.in.got->hasGotOffRel.store(true, std::memory_order_relaxed);
+  }
+
+  // Process TLS relocations, including TLS optimizations. Note that
+  // R_TPREL and R_TPREL_NEG relocations are resolved in processAux.
+  //
+  // Some RISCV TLSDESC relocations reference a local NOTYPE symbol,
+  // but we need to process them in handleTlsRelocation.
+  if (sym.isTls() || oneof<R_TLSDESC_PC, R_TLSDESC_CALL>(expr)) {
+    if (unsigned processed =
+            handleTlsRelocation(expr, type, offset, sym, addend)) {
+      it += processed - 1;
+      return;
+    }
+  }
+
+  process(expr, type, offset, sym, addend);
+}
+} // namespace lld::elf
+
+#endif