[BOLT][NFC] Infailable fns return void (#92018)

Both `reverseBranchCondition` and `replaceBranchTarget` return a success boolean. But all-but-one caller ignores the return value, and the exception emits a fatal error on failure.

Thus, just return nothing.

Author: urnathan

bolt/include/bolt/Core/MCPlusBuilder.h

@@ -1706,12 +1706,9 @@ class MCPlusBuilder {
   }
 
   /// Reverses the branch condition in Inst and update its taken target to TBB.
-  ///
-  /// Returns true on success.
-  virtual bool reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
+  virtual void reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
                                       MCContext *Ctx) const {
     llvm_unreachable("not implemented");
-    return false;
   }
 
   virtual bool replaceBranchCondition(MCInst &Inst, const MCSymbol *TBB,
@@ -1751,12 +1748,9 @@ class MCPlusBuilder {
   }
 
   /// Sets the taken target of the branch instruction to Target.
-  ///
-  /// Returns true on success.
-  virtual bool replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
+  virtual void replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
                                    MCContext *Ctx) const {
     llvm_unreachable("not implemented");
-    return false;
   }
 
   /// Extract a symbol and an addend out of the fixup value expression.

bolt/lib/Passes/VeneerElimination.cpp

@@ -77,11 +77,8 @@ Error VeneerElimination::runOnFunctions(BinaryContext &BC) {
           continue;
 
         VeneerCallers++;
-        if (!BC.MIB->replaceBranchTarget(
-                Instr, VeneerDestinations[TargetSymbol], BC.Ctx.get())) {
-          return createFatalBOLTError(
-              "BOLT-ERROR: updating veneer call destination failed\n");
-        }
+        BC.MIB->replaceBranchTarget(Instr, VeneerDestinations[TargetSymbol],
+                                    BC.Ctx.get());
       }
     }
   }

bolt/lib/Target/AArch64/AArch64MCPlusBuilder.cpp

@@ -616,7 +616,7 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
     return getTargetAddend(Op.getExpr());
   }
 
-  bool replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
+  void replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
                            MCContext *Ctx) const override {
     assert((isCall(Inst) || isBranch(Inst)) && !isIndirectBranch(Inst) &&
            "Invalid instruction");
@@ -638,7 +638,6 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
 
     *OI = MCOperand::createExpr(
         MCSymbolRefExpr::create(TBB, MCSymbolRefExpr::VK_None, *Ctx));
-    return true;
   }
 
   /// Matches indirect branch patterns in AArch64 related to a jump table (JT),
@@ -969,7 +968,7 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
     }
   }
 
-  bool reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
+  void reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
                               MCContext *Ctx) const override {
     if (isTB(Inst) || isCB(Inst)) {
       Inst.setOpcode(getInvertedBranchOpcode(Inst.getOpcode()));
@@ -984,7 +983,7 @@ class AArch64MCPlusBuilder : public MCPlusBuilder {
       LLVM_DEBUG(Inst.dump());
       llvm_unreachable("Unrecognized branch instruction");
     }
-    return replaceBranchTarget(Inst, TBB, Ctx);
+    replaceBranchTarget(Inst, TBB, Ctx);
   }
 
   int getPCRelEncodingSize(const MCInst &Inst) const override {

bolt/lib/Target/RISCV/RISCVMCPlusBuilder.cpp

@@ -151,14 +151,14 @@ class RISCVMCPlusBuilder : public MCPlusBuilder {
     }
   }
 
-  bool reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
+  void reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
                               MCContext *Ctx) const override {
     auto Opcode = getInvertedBranchOpcode(Inst.getOpcode());
     Inst.setOpcode(Opcode);
-    return replaceBranchTarget(Inst, TBB, Ctx);
+    replaceBranchTarget(Inst, TBB, Ctx);
   }
 
-  bool replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
+  void replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
                            MCContext *Ctx) const override {
     assert((isCall(Inst) || isBranch(Inst)) && !isIndirectBranch(Inst) &&
            "Invalid instruction");
@@ -170,7 +170,6 @@ class RISCVMCPlusBuilder : public MCPlusBuilder {
 
     Inst.getOperand(SymOpIndex) = MCOperand::createExpr(
         MCSymbolRefExpr::create(TBB, MCSymbolRefExpr::VK_None, *Ctx));
-    return true;
   }
 
   IndirectBranchType analyzeIndirectBranch(

bolt/lib/Target/X86/X86MCPlusBuilder.cpp

@@ -2794,14 +2794,13 @@ class X86MCPlusBuilder : public MCPlusBuilder {
     Inst.addOperand(MCOperand::createImm(CC));
   }
 
-  bool reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
+  void reverseBranchCondition(MCInst &Inst, const MCSymbol *TBB,
                               MCContext *Ctx) const override {
     unsigned InvCC = getInvertedCondCode(getCondCode(Inst));
     assert(InvCC != X86::COND_INVALID && "invalid branch instruction");
     Inst.getOperand(Info->get(Inst.getOpcode()).NumOperands - 1).setImm(InvCC);
     Inst.getOperand(0) = MCOperand::createExpr(
         MCSymbolRefExpr::create(TBB, MCSymbolRefExpr::VK_None, *Ctx));
-    return true;
   }
 
   bool replaceBranchCondition(MCInst &Inst, const MCSymbol *TBB, MCContext *Ctx,
@@ -2844,13 +2843,12 @@ class X86MCPlusBuilder : public MCPlusBuilder {
     }
   }
 
-  bool replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
+  void replaceBranchTarget(MCInst &Inst, const MCSymbol *TBB,
                            MCContext *Ctx) const override {
     assert((isCall(Inst) || isBranch(Inst)) && !isIndirectBranch(Inst) &&
            "Invalid instruction");
     Inst.getOperand(0) = MCOperand::createExpr(
         MCSymbolRefExpr::create(TBB, MCSymbolRefExpr::VK_None, *Ctx));
-    return true;
   }
 
   MCPhysReg getX86R11() const override { return X86::R11; }