MCAsmBackend: Remove redundant relaxInstruction overrides

Author: MaskRay

llvm/include/llvm/MC/MCAsmBackend.h

@@ -174,7 +174,11 @@ class LLVM_ABI MCAsmBackend {
   /// instruction.
   /// \param STI the subtarget information for the associated instruction.
   virtual void relaxInstruction(MCInst &Inst,
-                                const MCSubtargetInfo &STI) const {};
+                                const MCSubtargetInfo &STI) const {
+    llvm_unreachable(
+        "Needed if fixupNeedsRelaxation/fixupNeedsRelaxationAdvanced may "
+        "return true");
+  }
 
   // Defined by linker relaxation targets.
   virtual bool relaxDwarfLineAddr(MCDwarfLineAddrFragment &DF,

llvm/lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp

@@ -84,8 +84,6 @@ class AArch64AsmBackend : public MCAsmBackend {
 
   bool fixupNeedsRelaxation(const MCFixup &Fixup,
                             uint64_t Value) const override;
-  void relaxInstruction(MCInst &Inst,
-                        const MCSubtargetInfo &STI) const override;
   bool writeNopData(raw_ostream &OS, uint64_t Count,
                     const MCSubtargetInfo *STI) const override;
 
@@ -509,11 +507,6 @@ bool AArch64AsmBackend::fixupNeedsRelaxation(const MCFixup &Fixup,
   return int64_t(Value) != int64_t(int8_t(Value));
 }
 
-void AArch64AsmBackend::relaxInstruction(MCInst &Inst,
-                                         const MCSubtargetInfo &STI) const {
-  llvm_unreachable("AArch64AsmBackend::relaxInstruction() unimplemented");
-}
-
 bool AArch64AsmBackend::writeNopData(raw_ostream &OS, uint64_t Count,
                                      const MCSubtargetInfo *STI) const {
   // If the count is not 4-byte aligned, we must be writing data into the text

llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp

@@ -128,12 +128,6 @@ class PPCAsmBackend : public MCAsmBackend {
     }
   }
 
-  void relaxInstruction(MCInst &Inst,
-                        const MCSubtargetInfo &STI) const override {
-    // FIXME.
-    llvm_unreachable("relaxInstruction() unimplemented");
-  }
-
   bool writeNopData(raw_ostream &OS, uint64_t Count,
                     const MCSubtargetInfo *STI) const override {
     uint64_t NumNops = Count / 4;

llvm/lib/Target/VE/MCTargetDesc/VEAsmBackend.cpp

@@ -123,12 +123,6 @@ class VEAsmBackend : public MCAsmBackend {
     return false;
   }
 
-  void relaxInstruction(MCInst &Inst,
-                        const MCSubtargetInfo &STI) const override {
-    // Aurora VE doesn't support relaxInstruction yet.
-    llvm_unreachable("relaxInstruction() should not be called");
-  }
-
   bool writeNopData(raw_ostream &OS, uint64_t Count,
                     const MCSubtargetInfo *STI) const override {
     if ((Count % 8) != 0)

llvm/lib/Target/Xtensa/MCTargetDesc/XtensaAsmBackend.cpp

@@ -41,8 +41,6 @@ class XtensaAsmBackend : public MCAsmBackend {
                   bool IsResolved) override;
   bool mayNeedRelaxation(const MCInst &Inst,
                          const MCSubtargetInfo &STI) const override;
-  void relaxInstruction(MCInst &Inst,
-                        const MCSubtargetInfo &STI) const override;
   bool writeNopData(raw_ostream &OS, uint64_t Count,
                     const MCSubtargetInfo *STI) const override;
 
@@ -185,9 +183,6 @@ bool XtensaAsmBackend::mayNeedRelaxation(const MCInst &Inst,
   return false;
 }
 
-void XtensaAsmBackend::relaxInstruction(MCInst &Inst,
-                                        const MCSubtargetInfo &STI) const {}
-
 bool XtensaAsmBackend::writeNopData(raw_ostream &OS, uint64_t Count,
                                     const MCSubtargetInfo *STI) const {
   uint64_t NumNops24b = Count / 3;