[MC] Move ELF-specific handleAddSubRelocations to ELFObjectWriter::recordRelocation

Author: MaskRay

llvm/lib/MC/ELFObjectWriter.cpp

@@ -1377,6 +1377,12 @@ void ELFObjectWriter::recordRelocation(MCAssembler &Asm,
   const MCTargetOptions *TO = Ctx.getTargetOptions();
 
   if (auto *RefB = Target.getSubSym()) {
+    // When there is no relocation specifier, a linker relaxation target may
+    // emit ADD/SUB relocations for A-B+C.
+    if (Target.getSymA() && Backend.handleAddSubRelocations(
+                                Asm, *Fragment, Fixup, Target, FixedValue))
+      return;
+
     const auto &SymB = cast<MCSymbolELF>(*RefB);
     if (SymB.isUndefined()) {
       Ctx.reportError(Fixup.getLoc(),

llvm/lib/MC/MCAssembler.cpp

@@ -234,13 +234,6 @@ bool MCAssembler::evaluateFixup(const MCFixup &Fixup, const MCFragment *DF,
     }
   }
 
-  // A linker relaxation target may emit ADD/SUB relocations for A-B+C. Let
-  // recordRelocation handle non-VK_None cases like A@plt-B+C.
-  if (!IsResolved && Target.getSymA() && Target.getSubSym() &&
-      Target.getRefKind() == 0 &&
-      getBackend().handleAddSubRelocations(*this, *DF, Fixup, Target, Value))
-    return true;
-
   return IsResolved;
 }
 

llvm/lib/Target/LoongArch/MCTargetDesc/LoongArchAsmBackend.cpp

@@ -452,6 +452,8 @@ bool LoongArchAsmBackend::handleAddSubRelocations(const MCAssembler &Asm,
                                                   const MCFixup &Fixup,
                                                   const MCValue &Target,
                                                   uint64_t &FixedValue) const {
+  assert(Target.getRefKind() == 0 &&
+         "relocatable SymA-SymB cannot have relocation specifier");
   std::pair<MCFixupKind, MCFixupKind> FK;
   uint64_t FixedValueA, FixedValueB;
   const MCSymbol &SA = Target.getSymA()->getSymbol();

llvm/lib/Target/RISCV/MCTargetDesc/RISCVAsmBackend.cpp

@@ -590,6 +590,8 @@ bool RISCVAsmBackend::handleAddSubRelocations(const MCAssembler &Asm,
                                               const MCFixup &Fixup,
                                               const MCValue &Target,
                                               uint64_t &FixedValue) const {
+  assert(Target.getRefKind() == 0 &&
+         "relocatable SymA-SymB cannot have relocation specifier");
   uint64_t FixedValueA, FixedValueB;
   unsigned TA = 0, TB = 0;
   switch (Fixup.getKind()) {