[ELF] Implement getImplicitAddend and enable checkDynamicRelocsDefault for Hexagon

Author: MaskRay

lld/ELF/Arch/Hexagon.cpp

@@ -29,6 +29,7 @@ class Hexagon final : public TargetInfo {
   RelExpr getRelExpr(RelType type, const Symbol &s,
                      const uint8_t *loc) const override;
   RelType getDynRel(RelType type) const override;
+  int64_t getImplicitAddend(const uint8_t *buf, RelType type) const override;
   void relocate(uint8_t *loc, const Relocation &rel,
                 uint64_t val) const override;
   void writePltHeader(uint8_t *buf) const override;
@@ -386,6 +387,25 @@ RelType Hexagon::getDynRel(RelType type) const {
   return R_HEX_NONE;
 }
 
+int64_t Hexagon::getImplicitAddend(const uint8_t *buf, RelType type) const {
+  switch (type) {
+  case R_HEX_NONE:
+  case R_HEX_GLOB_DAT:
+  case R_HEX_JMP_SLOT:
+    return 0;
+  case R_HEX_32:
+  case R_HEX_RELATIVE:
+  case R_HEX_DTPMOD_32:
+  case R_HEX_DTPREL_32:
+  case R_HEX_TPREL_32:
+    return SignExtend64<32>(read32(buf));
+  default:
+    internalLinkerError(getErrorLocation(buf),
+                        "cannot read addend for relocation " + toString(type));
+    return 0;
+  }
+}
+
 TargetInfo *elf::getHexagonTargetInfo() {
   static Hexagon target;
   return &target;

lld/ELF/Driver.cpp

@@ -1709,11 +1709,10 @@ static void setConfigs(opt::InputArgList &args) {
                                       OPT_no_apply_dynamic_relocs, false) ||
                          !config->isRela;
   // Validation of dynamic relocation addends is on by default for assertions
-  // builds (for supported targets) and disabled otherwise. Ideally we would
-  // enable the debug checks for all targets, but currently not all targets
-  // have support for reading Elf_Rel addends, so we only enable for a subset.
+  // builds and disabled otherwise. This check is enabled when writeAddends is
+  // true.
 #ifndef NDEBUG
-  bool checkDynamicRelocsDefault = m != EM_HEXAGON;
+  bool checkDynamicRelocsDefault = true;
 #else
   bool checkDynamicRelocsDefault = false;
 #endif