[llvm] [BOLT][RISCV] Fix atomic-add operand order (PR #215493)

[via llvm-commits]

https://github.com/Thrrreeee created https://github.com/llvm/llvm-project/pull/215493

Since https://github.com/llvm/llvm-project/pull/162411 changed the internal AMO operand order to rd, rs2 (value), rs1 (address), BOLT should construct the instruction as RegAtomic, RegCnt, RegTo.

>From 5599723aaf8ae114cca05d5a4abe6e1cdcf2e480 Mon Sep 17 00:00:00 2001
From: Thrrreeeee <1379998393 at qq.com>
Date: Wed, 5 Aug 2026 11:08:49 +0800
Subject: [PATCH] [BOLT][RISCV] Fix atomic-add operand order

---
 bolt/lib/Target/RISCV/RISCVMCPlusBuilder.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/bolt/lib/Target/RISCV/RISCVMCPlusBuilder.cpp b/bolt/lib/Target/RISCV/RISCVMCPlusBuilder.cpp
index d1a0572277874..e2de69fa1875c 100644
--- a/bolt/lib/Target/RISCV/RISCVMCPlusBuilder.cpp
+++ b/bolt/lib/Target/RISCV/RISCVMCPlusBuilder.cpp
@@ -555,10 +555,11 @@ class RISCVMCPlusBuilder : public MCPlusBuilder {
 
   void atomicAdd(MCInst &Inst, MCPhysReg RegAtomic, MCPhysReg RegTo,
                  MCPhysReg RegCnt) const {
+    // AMO operands are ordered as rd, rs2 (value), rs1 (address).
     Inst = MCInstBuilder(atomicAddOpc())
                .addReg(RegAtomic)
-               .addReg(RegTo)
-               .addReg(RegCnt);
+               .addReg(RegCnt)
+               .addReg(RegTo);
   }
 
   InstructionListType createRegCmpJE(MCPhysReg RegNo, const MCSymbol *Target,