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perf: optimise VM runtime execution loop #7

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Merged
corepunch merged 1 commit into from
Apr 15, 2026
Merged

perf: optimise VM runtime execution loop #7

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33 changes: 17 additions & 16 deletions armvm/armvm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -141,7 +141,7 @@ _ARMPROC _dp1[] = {
f_NOP,
};

BOOL _condition(LPVM vm, DWORD cond) {
static BOOL _condition(LPVM vm, DWORD cond) {
DWORD f = vm->cpsr;
switch (cond) {
case OPCOND_EQ: // Z set, equal
Expand Down Expand Up @@ -178,7 +178,7 @@ BOOL _condition(LPVM vm, DWORD cond) {
}
}

DWORD _calcshift(LPVM vm, DWORD instr) {
static DWORD _calcshift(LPVM vm, DWORD instr) {
DWORD Rm = instr & 0b1111;
DWORD ShiftType = (instr >> 5) & 0b11;
DWORD ShiftAmount;
Expand All @@ -197,13 +197,14 @@ DWORD _calcshift(LPVM vm, DWORD instr) {
return 0;
}

DWORD _calcimmediate(LPVM vm, DWORD instr) {
static DWORD _calcimmediate(LPVM vm, DWORD instr) {
DWORD Imm = instr & 0xff;
DWORD Rotate = ((instr >> 8) & 0xf) << 1;
return Imm >> Rotate | (Imm << (32 - Rotate));
if (Rotate == 0) return Imm;
return (Imm >> Rotate) | (Imm << (32 - Rotate));
}

void exec_dataprocessing(LPVM vm, DWORD instr) {
static void exec_dataprocessing(LPVM vm, DWORD instr) {
BOOL Immediate = BIT_VALUE(instr, 25);
BOOL SetFlags = BIT_VALUE(instr, 20);
OPCODE OpCode = (instr >> 21) & 0xf;
Expand Down Expand Up @@ -232,7 +233,7 @@ static inline DWORD _offsetptr(DWORD Rn, DWORD Offset, BOOL Up) {
#define LDR_WRITEBACK_BIT 21
#define LDR_LOAD_BIT 20

void exec_datatransfer(LPVM vm, DWORD instr) {
static void exec_datatransfer(LPVM vm, DWORD instr) {
BOOL Pre = BIT_VALUE(instr, LDR_PREOFFSET_BIT);
BOOL Immediate = !BIT_VALUE(instr, 25);
BOOL Byte = BIT_VALUE(instr, LDR_BYTE_BIT);
Expand All @@ -258,7 +259,7 @@ void exec_datatransfer(LPVM vm, DWORD instr) {
#define LDRSB_HALFWORD_BIT 5
#define LDRSB_SIGNED_BIT 6

void exec_ldrsb(LPVM vm, DWORD instr, DWORD Rm) {
static void exec_ldrsb(LPVM vm, DWORD instr, DWORD Rm) {
BOOL Pre = BIT_VALUE(instr, LDR_PREOFFSET_BIT);
BOOL Immediate = BIT_VALUE(instr, LDRSB_IMMEDIATE_BIT);
BOOL Halfword = BIT_VALUE(instr, LDRSB_HALFWORD_BIT);
Expand All @@ -283,7 +284,7 @@ void exec_ldrsb(LPVM vm, DWORD instr, DWORD Rm) {
}
}

void exec_blockdatatransfer(LPVM vm, DWORD instr) {
static void exec_blockdatatransfer(LPVM vm, DWORD instr) {
BOOL Load = BIT_VALUE(instr, 20);
BOOL WriteBack = BIT_VALUE(instr, 21);
// BOOL SetFlags = BIT_VALUE(instr, 22);
Expand Down Expand Up @@ -312,7 +313,7 @@ void exec_blockdatatransfer(LPVM vm, DWORD instr) {

#define MASK_24BIT 0x00ffffff

void exec_branchwithlink(LPVM vm, DWORD instr) {
static void exec_branchwithlink(LPVM vm, DWORD instr) {
BOOL Link = BIT_VALUE(instr, 24);
BOOL Negative = BIT_VALUE(instr, 23);
DWORD Offset = instr & MASK_24BIT;
Expand All @@ -326,12 +327,12 @@ void exec_branchwithlink(LPVM vm, DWORD instr) {
}
}

void exec_branchandexchange(LPVM vm, DWORD instr) {
static void exec_branchandexchange(LPVM vm, DWORD instr) {
DWORD Rn = instr & 0xf;
vm->location = vm->r[Rn];
}

void exec_mul(LPVM vm, DWORD instr) {
static void exec_mul(LPVM vm, DWORD instr) {
BOOL Accumulate = BIT_VALUE(instr, 21);
BOOL SetFlags = BIT_VALUE(instr, 20);
DWORD Rm = REG_INSTR(vm, instr, 0);
Expand All @@ -352,7 +353,7 @@ void exec_mul(LPVM vm, DWORD instr) {
}
}

void exec_umul(LPVM vm, DWORD instr) {
static void exec_umul(LPVM vm, DWORD instr) {
typedef long long slong;
typedef unsigned long long ulong;
BOOL Accumulate = BIT_VALUE(instr, 21);
Expand Down Expand Up @@ -394,16 +395,17 @@ void exec_umul(LPVM vm, DWORD instr) {
}
}

void exec_branch_external(LPVM vm, DWORD instr) {
static void exec_branch_external(LPVM vm, DWORD instr) {
DWORD proc = instr & 0xffff;
*vm->r = vm->syscall(vm, proc);
}

void exec_instruction(LPVM vm) {
static void exec_instruction(LPVM vm) {
DWORD instr = *(DWORD *)(vm->memory + vm->location);
vm->location += REG_SIZE;
vm->r[PC_REG] = vm->location + REG_SIZE;
if (!_condition(vm, instr >> 28))
DWORD cond = instr >> 28;
if (__builtin_expect(cond != OPCOND_AL, 0) && !_condition(vm, cond))
return;
if ((instr & MASK_BX) == OP_BX) {
exec_branchandexchange(vm, instr);
Expand Down Expand Up @@ -459,7 +461,6 @@ void execute(LPVM vm, DWORD pc) {
vm->r[LR_REG] = vm->progsize;
vm->location = pc;
while (vm->location < vm->progsize) {
DWORD line = vm->location / 4 + 1;
exec_instruction(vm);
assert(vm->location != 0xffffffff);
}
Expand Down
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