[optimze]添加基础的除法指令优化，目前只对除以2的幂数生效

src/include/backend/RISCv64/Optimize/DivStrengthReduction.h

@@ -0,0 +1,30 @@
+#ifndef RISCV64_DIV_STRENGTH_REDUCTION_H
+#define RISCV64_DIV_STRENGTH_REDUCTION_H
+
+#include "RISCv64LLIR.h"
+#include "Pass.h"
+
+namespace sysy {
+
+/**
+ * @class DivStrengthReduction
+ * @brief 除法强度削弱优化器
+ * * 将除法运算转换为乘法运算，使用magic number算法
+ * 适用于除数为常数的情况，可以显著提高性能
+ */
+class DivStrengthReduction : public Pass {
+public:
+    static char ID;
+    
+    DivStrengthReduction() : Pass("div-strength-reduction", Granularity::Function, PassKind::Optimization) {}
+    
+    void *getPassID() const override { return &ID; }
+    
+    bool runOnFunction(Function *F, AnalysisManager& AM) override;
+    
+    void runOnMachineFunction(MachineFunction* mfunc);
+};
+
+} // namespace sysy
+
+#endif // RISCV64_DIV_STRENGTH_REDUCTION_H

src/include/backend/RISCv64/RISCv64Passes.h

@@ -9,6 +9,8 @@
 #include "LegalizeImmediates.h"
 #include "PrologueEpilogueInsertion.h"
 #include "Pass.h"
+#include "DivStrengthReduction.h"
+
 
 namespace sysy {