Optimize zeroing (#389)

Author: vtereshkov

playground/umka.js

@@ -93,6 +93,31 @@ static Instruction *getPrevInstr(CodeGen *gen, int depth)
 }
 
 
+static bool optimizePushLocalPtr(CodeGen *gen, int offset)
+{
+    Instruction *prev = getPrevInstr(gen, 1), *prev2 = getPrevInstr(gen, 2);
+
+    // Optimization: PUSH_LOCAL_PTR + ZERO + PUSH_LOCAL_PTR -> PUSH_LOCAL_PTR_ZERO
+    if (prev  && prev->opcode  == OP_ZERO &&
+        prev2 && prev2->opcode == OP_PUSH_LOCAL_PTR)
+    {
+        if (offset == prev2->operand.intVal)
+        {
+            const int size = prev->operand.intVal;
+
+            genRemoveInstr(gen);
+            genRemoveInstr(gen);
+            genPushLocalPtrZero(gen, offset, size);
+
+            genUnnotify(gen);
+            return true;
+        }
+    }
+
+    return false;
+}
+
+
 static bool optimizePushReg(CodeGen *gen, int regIndex)
 {
     Instruction *prev = getPrevInstr(gen, 1);
@@ -433,7 +458,17 @@ void genPushGlobalPtr(CodeGen *gen, void *ptrVal)
 
 void genPushLocalPtr(CodeGen *gen, int offset)
 {
-    const Instruction instr = {.opcode = OP_PUSH_LOCAL_PTR, .tokKind = TOK_NONE, .typeKind = TYPE_NONE, .operand.intVal = offset};
+    if (!optimizePushLocalPtr(gen, offset))
+    {
+        const Instruction instr = {.opcode = OP_PUSH_LOCAL_PTR, .tokKind = TOK_NONE, .typeKind = TYPE_NONE, .operand.intVal = offset};
+        genAddInstr(gen, &instr);
+    }
+}
+
+
+void genPushLocalPtrZero(CodeGen *gen, int offset, int size)
+{
+    const Instruction instr = {.opcode = OP_PUSH_LOCAL_PTR_ZERO, .tokKind = TOK_NONE, .typeKind = TYPE_NONE, .operand.int32Val = {offset, size}};
     genAddInstr(gen, &instr);
 }
 

src/umka_gen.c

@@ -48,16 +48,17 @@ void genFree(CodeGen *gen);
 
 void genNop(CodeGen *gen);
 
-void genPushIntConst (CodeGen *gen, int64_t intVal);
-void genPushUIntConst(CodeGen *gen, uint64_t uintVal);
-void genPushRealConst(CodeGen *gen, double realVal);
-void genPushGlobalPtr(CodeGen *gen, void *ptrVal);
-void genPushLocalPtr (CodeGen *gen, int offset);
-void genPushLocal    (CodeGen *gen, TypeKind typeKind, int offset);
-void genPushReg      (CodeGen *gen, int regIndex);
-void genPushStruct   (CodeGen *gen, int size);
-void genPushUpvalue  (CodeGen *gen);
-void genPushZero     (CodeGen *gen, int slots);
+void genPushIntConst    (CodeGen *gen, int64_t intVal);
+void genPushUIntConst   (CodeGen *gen, uint64_t uintVal);
+void genPushRealConst   (CodeGen *gen, double realVal);
+void genPushGlobalPtr   (CodeGen *gen, void *ptrVal);
+void genPushLocalPtr    (CodeGen *gen, int offset);
+void genPushLocalPtrZero(CodeGen *gen, int offset, int size);
+void genPushLocal       (CodeGen *gen, TypeKind typeKind, int offset);
+void genPushReg         (CodeGen *gen, int regIndex);
+void genPushStruct      (CodeGen *gen, int size);
+void genPushUpvalue     (CodeGen *gen);
+void genPushZero        (CodeGen *gen, int slots);
 
 void genPop   (CodeGen *gen);
 void genPopReg(CodeGen *gen, int regIndex);

src/umka_gen.h

@@ -29,6 +29,7 @@ static const char *opcodeSpelling [] =
     "PUSH",
     "PUSH_ZERO",
     "PUSH_LOCAL_PTR",
+    "PUSH_LOCAL_PTR_ZERO",
     "PUSH_LOCAL",
     "PUSH_REG",
     "PUSH_STRUCT",
@@ -2494,15 +2495,22 @@ static FORCE_INLINE void doPushZero(Fiber *fiber, Error *error)
 
 static FORCE_INLINE void doPushLocalPtr(Fiber *fiber)
 {
-    // Local variable addresses are offsets (in bytes) from the stack/heap frame base pointer
     (--fiber->top)->ptrVal = (int8_t *)fiber->base + fiber->code[fiber->ip].operand.intVal;
     fiber->ip++;
 }
 
 
+static FORCE_INLINE void doPushLocalPtrZero(Fiber *fiber)
+{
+    (--fiber->top)->ptrVal = (int8_t *)fiber->base + fiber->code[fiber->ip].operand.int32Val[0];
+    int size = fiber->code[fiber->ip].operand.int32Val[1];
+    memset(fiber->top->ptrVal, 0, size);
+    fiber->ip++;
+}
+
+
 static FORCE_INLINE void doPushLocal(Fiber *fiber, Error *error)
 {
-    // Local variable addresses are offsets (in bytes) from the stack/heap frame base pointer
     (--fiber->top)->ptrVal = (int8_t *)fiber->base + fiber->code[fiber->ip].operand.intVal;
     doBasicDeref(fiber->top, fiber->code[fiber->ip].typeKind, error);
     fiber->ip++;
@@ -3325,6 +3333,7 @@ static FORCE_INLINE void vmLoop(VM *vm)
             case OP_PUSH:                           doPush(fiber, error);                         break;
             case OP_PUSH_ZERO:                      doPushZero(fiber, error);                     break;
             case OP_PUSH_LOCAL_PTR:                 doPushLocalPtr(fiber);                        break;
+            case OP_PUSH_LOCAL_PTR_ZERO:            doPushLocalPtrZero(fiber);                    break;
             case OP_PUSH_LOCAL:                     doPushLocal(fiber, error);                    break;
             case OP_PUSH_REG:                       doPushReg(fiber);                             break;
             case OP_PUSH_STRUCT:                    doPushStruct(fiber, error);                   break;
@@ -3489,6 +3498,7 @@ int vmAsm(int ip, Instruction *code, DebugInfo *debugPerInstr, char *buf, int si
             chars += snprintf(buf + chars, nonneg(size - chars), " %s (%lld)", fnName, (long long int)instr->operand.intVal);
             break;
         }
+        case OP_PUSH_LOCAL_PTR_ZERO:
         case OP_GET_ARRAY_PTR:          chars += snprintf(buf + chars, nonneg(size - chars), " %d %d", (int)instr->operand.int32Val[0], (int)instr->operand.int32Val[1]); break;
         case OP_CALL_EXTERN:            chars += snprintf(buf + chars, nonneg(size - chars), " %p",    instr->operand.ptrVal); break;
         case OP_CALL_BUILTIN:           chars += snprintf(buf + chars, nonneg(size - chars), " %s",    builtinSpelling[instr->operand.builtinVal]); break;

src/umka_vm.c

@@ -36,6 +36,7 @@ typedef enum
     OP_PUSH,
     OP_PUSH_ZERO,
     OP_PUSH_LOCAL_PTR,
+    OP_PUSH_LOCAL_PTR_ZERO,
     OP_PUSH_LOCAL,
     OP_PUSH_REG,
     OP_PUSH_STRUCT,