增加了已分配寄存器的常量的优化

Author: ComradeProgrammer

MipsTranslator.cpp

@@ -90,7 +90,9 @@ void MipsTranslator::translateBlock(Block* b) {
 	}
 	//这里：暂时是把所有临时变量全部写回了，但是其实没这个必要，稍后可以加以改进
 	for (int i = 0; i < TMPREG; i++) {
-		varReg[Tuser[i]] = -1;
+		if (Tstatus[i] == REGVAR) {
+			varReg[Tuser[i]] = -1;
+		}
 		Tstatus[i] = REGFREE;
 		Tuser[i] = -1;
 	}
@@ -195,10 +197,14 @@ vector<int> MipsTranslator::TregisterAlloc(int var, int isImmediate
 		for (int i = 0; i < TMPREG; i++) {
 			if (Tstatus[i] == REGFREE) {
 				//如果找到了free状态的直接使用即可
-				if (isImmediate||var==-1) {
-					Tstatus[i] = REGOCCUPY;//改状态
+				if (!isImmediate && var == -1) {
+					Tstatus[i] = REGTMP;//改状态
 					Tuser[i] = -1;//改使用者
 				}
+				else if (isImmediate) {
+					Tstatus[i] = REGOCCUPY;//改状态
+					Tuser[i] = var;//改使用者
+				}
 				else {
 					Tstatus[i] = REGVAR;
 					Tuser[i] = var;
@@ -214,7 +220,7 @@ vector<int> MipsTranslator::TregisterAlloc(int var, int isImmediate
 					find(conflictVar.begin(), conflictVar.end(), Tuser[i]) != conflictVar.end()) {
 					continue;//不分配相关变量的寄存器
 				}
-				else if (Tstatus[i] == REGOCCUPY &&
+				else if ((Tstatus[i] == REGOCCUPY||Tstatus[i]==REGTMP)&&
 					find(conflictReg.begin(), conflictReg.end(), Tregister[i]) != conflictReg.end()) {
 					continue;//不分配相关变量占用的寄存器
 				}
@@ -225,10 +231,14 @@ vector<int> MipsTranslator::TregisterAlloc(int var, int isImmediate
 					if (entry->scope == "") {
 						continue;
 					}
-					if (isImmediate || var == -1) {
-						Tstatus[i] = REGOCCUPY;//改状态
+					if (!isImmediate && var == -1) {
+						Tstatus[i] = REGTMP;//改状态
 						Tuser[i] = -1;//改使用者
 					}
+					else if (isImmediate ) {
+						Tstatus[i] = REGOCCUPY;//改状态
+						Tuser[i] =var;//改使用者（常数）
+					}
 					else {
 						Tstatus[i] = REGVAR;
 						Tuser[i] = var;
@@ -244,21 +254,23 @@ vector<int> MipsTranslator::TregisterAlloc(int var, int isImmediate
 				find(conflictVar.begin(), conflictVar.end(), Tuser[i]) != conflictVar.end()) {
 				continue;//不分配相关的寄存器
 			}
-			else if (Tstatus[i] == REGOCCUPY &&
+			else if ((Tstatus[i] == REGOCCUPY || Tstatus[i] == REGTMP) &&
 				find(conflictReg.begin(), conflictReg.end(), Tregister[i]) != conflictReg.end()) {
 				continue;//不分配相关变量占用的寄存器
 			}
 			else {
 				//找到了一个T寄存器
-				if (Tstatus[i] == REGOCCUPY) {
-					//若是occupy状态无需写回
-					if (isImmediate || var == -1) {
-						//若是立即数/临时寄存器
-						Tstatus[i] = REGOCCUPY;//改状态
+				if (Tstatus[i] == REGOCCUPY||Tstatus[i]==REGTMP) {
+					//若是occupy状态或是临时占用无需写回
+					if (!isImmediate && var == -1) {
+						Tstatus[i] = REGTMP;//改状态
 						Tuser[i] = -1;//改使用者
 					}
+					else if (isImmediate) {
+						Tstatus[i] = REGOCCUPY;//改状态
+						Tuser[i] = var;//改使用者(常数)
+					}
 					else {
-						//若是变量
 						Tstatus[i] = REGVAR;
 						Tuser[i] = var;
 						varReg[var] = Tregister[i];//登记
@@ -268,10 +280,14 @@ vector<int> MipsTranslator::TregisterAlloc(int var, int isImmediate
 				else {
 					//需要写回
 					int old = Tuser[i];
-					if (isImmediate || var == -1) {
-						Tstatus[i] = REGOCCUPY;//改状态
+					if (!isImmediate && var == -1) {
+						Tstatus[i] = REGTMP;//改状态
 						Tuser[i] = -1;//改使用者
 					}
+					else if (isImmediate) {
+						Tstatus[i] = REGOCCUPY;//改状态
+						Tuser[i] = var;//改使用者
+					}
 					else {
 						Tstatus[i] = REGVAR;
 						Tuser[i] = var;
@@ -300,6 +316,12 @@ int MipsTranslator::loadOperand(int var, int isImmediate
 	}
 	else if (isImmediate) {
 		//是立即数
+		bool found = false;
+		for (int i = 0; i < TMPREG; i++) {
+			if (Tstatus[i] == REGOCCUPY && Tuser[i] == var) {
+				return Tregister[i];
+			}
+		}
 		vector<int>res = TregisterAlloc(var, isImmediate, conflictVar
 			, conflictReg, activeVariable);
 		if (res[1] != -1) { writeback(res[1], res[0]); }//写回

MipsTranslator.h

@@ -4,8 +4,11 @@
 #include<fstream>
 #define GLOBALREG 8
 #define TMPREG 10
+//是直接就是被临时分配的寄存器
+#define REGTMP 3
+//占用状态指里面存储着常数
 #define REGOCCUPY 2
-//占用状态指里面存储着常数或是直接就是被临时分配的寄存器
+
 #define REGVAR 1
 #define REGFREE 0
 using namespace std;

mips.txt

@@ -366,39 +366,38 @@ mul $t4,$t3,$t3##TMP71 = #TMP63 * #TMP63
 
 mul $t5,$t4,$t3##TMP72 = #TMP71 * #TMP63
 
-li $t7,10	# load immediate 10
-div $t0,$t7
+div $t0,$t1
 mflo $t6##TMP44 = #TMP50 / 10
 
-mul $t8,$t6,10##TMP45 = #TMP44 * 10
+mul $t7,$t6,10##TMP45 = #TMP44 * 10
 
-subu $t9,$t0,$t8##TMP64 = #TMP50 - #TMP45
+subu $t8,$t0,$t7##TMP64 = #TMP50 - #TMP45
 
-mul $t0,$t9,$t9##TMP68 = #TMP64 * #TMP64
+mul $t9,$t8,$t8##TMP68 = #TMP64 * #TMP64
 
-mul $t2,$t0,$t9##TMP69 = #TMP68 * #TMP64
+mul $t0,$t9,$t8##TMP69 = #TMP68 * #TMP64
 
 li $t4,100	# load immediate 100
 div $s0,$t4
-mflo $t0##TMP65 = i / 100
+mflo $t2##TMP65 = i / 100
 
-mul $t6,$t0,$t0##TMP66 = #TMP65 * #TMP65
+mul $t6,$t2,$t2##TMP66 = #TMP65 * #TMP65
 
-mul $t8,$t6,$t0##TMP67 = #TMP66 * #TMP65
+mul $t7,$t6,$t2##TMP67 = #TMP66 * #TMP65
 
-addu $t6,$t8,$t2##TMP70 = #TMP67 + #TMP69
+addu $t6,$t7,$t0##TMP70 = #TMP67 + #TMP69
 
-addu $t2,$t6,$t5##TMP73 = #TMP70 + #TMP72
+addu $t0,$t6,$t5##TMP73 = #TMP70 + #TMP72
 
-mul $t5,$t9,10##TMP58 = #TMP64 * 10
+mul $t5,$t8,10##TMP58 = #TMP64 * 10
 
-mul $t6,$t0,100##TMP57 = #TMP65 * 100
+mul $t6,$t2,100##TMP57 = #TMP65 * 100
 
-addu $t0,$t6,$t5##TMP59 = #TMP57 + #TMP58
+addu $t2,$t6,$t5##TMP59 = #TMP57 + #TMP58
 
-addu $t5,$t0,$t3##TMP60 = #TMP59 + #TMP63
+addu $t5,$t2,$t3##TMP60 = #TMP59 + #TMP63
 
-bne $t5,$t2,label$15
+bne $t5,$t0,label$15
 ##TMP74 = #TMP60 == #TMP73
 
 #BZ #TMP74 _label15

testfile.txt

@@ -126,4 +126,4 @@ void main()
    swap(5, 10 ) ;
 
    complete_flower_num() ;
-}
+}