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Enhance algebraic simplifications
Add comprehensive algebraic optimization patterns: - Self-operations: x-x=0, x^x=0, x&x=x, x|x=x - Comparisons: x==x=1, x!=x=0, x<x=0, x<=x=1 - Identity operations: x+0=x, x*1=x, x&-1=x - Constant folding: x*0=0, x&0=0, x|-1=-1 - Special cases: x%1=0, x*-1=-x, x<<0=x These patterns improve code generation by eliminating redundant operations and simplifying expressions at compile time.
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‎src/ssa.c‎

Lines changed: 131 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1920,6 +1920,137 @@ void optimize(void)
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}
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}
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/* Enhanced algebraic simplifications */
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/* Self-operation optimizations */
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if (insn->rs1 && insn->rs2 && insn->rs1 == insn->rs2) {
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/* x - x = 0 */
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if (insn->opcode == OP_sub && insn->rd) {
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insn->opcode = OP_load_constant;
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insn->rd->is_const = true;
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insn->rd->init_val = 0;
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insn->rs1 = NULL;
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insn->rs2 = NULL;
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}
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/* x ^ x = 0 */
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else if (insn->opcode == OP_bit_xor && insn->rd) {
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insn->opcode = OP_load_constant;
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insn->rd->is_const = true;
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insn->rd->init_val = 0;
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insn->rs1 = NULL;
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insn->rs2 = NULL;
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}
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/* x & x = x */
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else if (insn->opcode == OP_bit_and && insn->rd) {
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insn->opcode = OP_assign;
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insn->rs2 = NULL;
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}
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/* x | x = x */
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else if (insn->opcode == OP_bit_or && insn->rd) {
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insn->opcode = OP_assign;
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insn->rs2 = NULL;
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}
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/* x == x = 1 */
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else if (insn->opcode == OP_eq && insn->rd) {
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insn->opcode = OP_load_constant;
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insn->rd->is_const = true;
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insn->rd->init_val = 1;
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insn->rs1 = NULL;
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insn->rs2 = NULL;
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}
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/* x != x = 0 */
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else if (insn->opcode == OP_neq && insn->rd) {
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insn->opcode = OP_load_constant;
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insn->rd->is_const = true;
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insn->rd->init_val = 0;
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insn->rs1 = NULL;
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insn->rs2 = NULL;
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}
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/* x < x = 0, x > x = 0 */
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else if ((insn->opcode == OP_lt || insn->opcode == OP_gt) &&
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insn->rd) {
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insn->opcode = OP_load_constant;
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insn->rd->is_const = true;
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insn->rd->init_val = 0;
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insn->rs1 = NULL;
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insn->rs2 = NULL;
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}
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/* x <= x = 1, x >= x = 1 */
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else if ((insn->opcode == OP_leq ||
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insn->opcode == OP_geq) &&
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insn->rd) {
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insn->opcode = OP_load_constant;
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insn->rd->is_const = true;
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insn->rd->init_val = 1;
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insn->rs1 = NULL;
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insn->rs2 = NULL;
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}
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}
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/* Identity and constant optimizations */
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if (insn->rs2 && insn->rs2->is_const && insn->rd) {
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int val = insn->rs2->init_val;
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/* x + 0 = x, x - 0 = x, x | 0 = x, x ^ 0 = x */
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if (val == 0) {
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if (insn->opcode == OP_add || insn->opcode == OP_sub ||
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insn->opcode == OP_bit_or ||
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insn->opcode == OP_bit_xor) {
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insn->opcode = OP_assign;
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insn->rs2 = NULL;
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}
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/* x * 0 = 0, x & 0 = 0 */
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else if (insn->opcode == OP_mul ||
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insn->opcode == OP_bit_and) {
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insn->opcode = OP_load_constant;
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insn->rd->is_const = true;
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insn->rd->init_val = 0;
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insn->rs1 = NULL;
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insn->rs2 = NULL;
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}
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/* x << 0 = x, x >> 0 = x */
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else if (insn->opcode == OP_lshift ||
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insn->opcode == OP_rshift) {
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insn->opcode = OP_assign;
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insn->rs2 = NULL;
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}
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}
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/* x * 1 = x, x / 1 = x */
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else if (val == 1) {
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if (insn->opcode == OP_mul || insn->opcode == OP_div) {
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insn->opcode = OP_assign;
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insn->rs2 = NULL;
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}
2023+
/* x % 1 = 0 */
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else if (insn->opcode == OP_mod) {
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insn->opcode = OP_load_constant;
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insn->rd->is_const = true;
2027+
insn->rd->init_val = 0;
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insn->rs1 = NULL;
2029+
insn->rs2 = NULL;
2030+
}
2031+
}
2032+
/* x & -1 = x (all bits set) */
2033+
else if (val == -1) {
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if (insn->opcode == OP_bit_and) {
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insn->opcode = OP_assign;
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insn->rs2 = NULL;
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}
2038+
/* x | -1 = -1 */
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else if (insn->opcode == OP_bit_or) {
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insn->opcode = OP_load_constant;
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insn->rd->is_const = true;
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insn->rd->init_val = -1;
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insn->rs1 = NULL;
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insn->rs2 = NULL;
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}
2046+
/* x * -1 = -x */
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else if (insn->opcode == OP_mul) {
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insn->opcode = OP_negate;
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insn->rs2 = NULL;
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}
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}
2052+
}
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/* more optimizations */
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}
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}

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