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Generate a sequence of instructions for divisions on Arm targets #126

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merged 1 commit into from
Apr 5, 2024
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Generate a sequence of instructions for divisions on Arm targets #126

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3 changes: 2 additions & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -91,11 +91,12 @@ Run `make` and you should see this:

File `out/shecc` is the first stage compiler. Its usage:
```
shecc [-o output] [--no-libc] [--dump-ir] <infile.c>
shecc [-o output] [+m] [--no-libc] [--dump-ir] <infile.c>
```

Compiler options:
- `-o` : output file name (default: out.elf)
- `+m` : Enable hardware multiplication and division instructions (default: disabled)
- `--no-libc` : Exclude embedded C library (default: embedded)
- `--dump-ir` : Dump intermediate representation (IR)

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88 changes: 82 additions & 6 deletions src/arm-codegen.c
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Expand Up @@ -74,7 +74,6 @@ void update_elf_offset(ph2_ir_t *ph2_ir)
case OP_add:
case OP_sub:
case OP_mul:
case OP_div:
case OP_lshift:
case OP_rshift:
case OP_bit_and:
Expand All @@ -85,11 +84,24 @@ void update_elf_offset(ph2_ir_t *ph2_ir)
case OP_bit_not:
elf_offset += 4;
return;
case OP_div:
if (hard_mul_div) {
elf_offset += 4;
} else {
elf_offset += 104;
}
return;
case OP_mod:
if (hard_mul_div) {
elf_offset += 12;
} else {
elf_offset += 104;
}
return;
case OP_load_data_address:
elf_offset += 8;
return;
case OP_address_of_func:
case OP_mod:
case OP_eq:
case OP_neq:
case OP_gt:
Expand Down Expand Up @@ -323,12 +335,76 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
emit(__mul(__AL, rd, rn, rm));
return;
case OP_div:
emit(__div(__AL, rd, rm, rn));
if (hard_mul_div) {
emit(__div(__AL, rd, rm, rn));
} else {
/* Obtain absoulte values of dividend and divisor */
emit(__srl_amt(__AL, 0, arith_rs, __r8, rn, 31));
emit(__add_r(__AL, rn, rn, __r8));
emit(__eor_r(__AL, rn, rn, __r8));
emit(__srl_amt(__AL, 0, arith_rs, __r9, rm, 31));
emit(__add_r(__AL, rm, rm, __r9));
emit(__eor_r(__AL, rm, rm, __r9));
emit(__eor_r(__AL, __r10, __r8, __r9));
/* Unsigned integer division */
emit(__zero(__r9));
emit(__mov_i(__AL, __r8, 1));
emit(__cmp_i(__AL, rm, 0));
emit(__b(__EQ, 52));
emit(__cmp_i(__AL, rn, 0));
emit(__b(__EQ, 44));
emit(__cmp_r(__AL, rm, rn));
emit(__sll_amt(__CC, 0, logic_ls, rm, rm, 1));
emit(__sll_amt(__CC, 0, logic_ls, __r8, __r8, 1));
emit(__b(__CC, -12));
emit(__cmp_r(__AL, rn, rm));
emit(__sub_r(__CS, rn, rn, rm));
emit(__add_r(__CS, __r9, __r9, __r8));
emit(__srl_amt(__AL, 1, logic_rs, __r8, __r8, 1));
emit(__srl_amt(__CC, 0, logic_rs, rm, rm, 1));
emit(__b(__CC, -20));
emit(__mov_r(__AL, rd, __r9));
/* Handle the correct sign for quotient */
emit(__cmp_i(__AL, __r10, 0));
emit(__rsb_i(__NE, rd, 0, rd));
}
return;
case OP_mod:
emit(__div(__AL, __r8, rm, rn));
emit(__mul(__AL, __r8, rm, __r8));
emit(__sub_r(__AL, rd, rn, __r8));
if (hard_mul_div) {
emit(__div(__AL, __r8, rm, rn));
emit(__mul(__AL, __r8, rm, __r8));
emit(__sub_r(__AL, rd, rn, __r8));
} else {
/* Obtain absoulte values of dividend and divisor */
emit(__srl_amt(__AL, 0, arith_rs, __r8, rn, 31));
emit(__add_r(__AL, rn, rn, __r8));
emit(__eor_r(__AL, rn, rn, __r8));
emit(__srl_amt(__AL, 0, arith_rs, __r9, rm, 31));
emit(__add_r(__AL, rm, rm, __r9));
emit(__eor_r(__AL, rm, rm, __r9));
emit(__mov_r(__AL, __r10, __r8));
/* Unsigned integer division */
emit(__zero(__r9));
emit(__mov_i(__AL, __r8, 1));
emit(__cmp_i(__AL, rm, 0));
emit(__b(__EQ, 52));
emit(__cmp_i(__AL, rn, 0));
emit(__b(__EQ, 44));
emit(__cmp_r(__AL, rm, rn));
emit(__sll_amt(__CC, 0, logic_ls, rm, rm, 1));
emit(__sll_amt(__CC, 0, logic_ls, __r8, __r8, 1));
emit(__b(__CC, -12));
emit(__cmp_r(__AL, rn, rm));
emit(__sub_r(__CS, rn, rn, rm));
emit(__add_r(__CS, __r9, __r9, __r8));
emit(__srl_amt(__AL, 1, logic_rs, __r8, __r8, 1));
emit(__srl_amt(__CC, 0, logic_rs, rm, rm, 1));
emit(__b(__CC, -20));
emit(__mov_r(__AL, rd, rn));
/* Handle the correct sign for remainder */
emit(__cmp_i(__AL, __r10, 0));
emit(__rsb_i(__NE, rd, 0, rd));
}
return;
case OP_lshift:
emit(__sll(__AL, rd, rn, rm));
Expand Down
37 changes: 37 additions & 0 deletions src/arm.c
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Expand Up @@ -47,6 +47,9 @@ typedef enum {
typedef enum {
__EQ = 0, /* Equal */
__NE = 1, /* Not equal */
__CS = 2, /* Unsigned higher or same */
__CC = 3, /* Unsigned lower */
__LS = 9, /* unsigned lower or same */
__GE = 10, /* Signed greater than or equal */
__LT = 11, /* Signed less than */
__GT = 12, /* Signed greater than */
Expand Down Expand Up @@ -74,6 +77,13 @@ typedef enum {
__pc = 15 /* program counter, r15 */
} arm_reg;

typedef enum {
logic_ls = 0, /* Logical left shift */
logic_rs = 1, /* Logical right shift */
arith_rs = 2, /* Arithmetic right shift */
rotat_rs = 3 /* Rotate right shift */
} shfit_type;

arm_cond_t arm_get_cond(opcode_t op)
{
switch (op) {
Expand Down Expand Up @@ -186,12 +196,34 @@ int __srl(arm_cond_t cond, arm_reg rd, arm_reg rm, arm_reg rs)
rm + (1 << 4) + (1 << 5) + (rs << 8));
}

int __srl_amt(arm_cond_t cond,
int s,
shfit_type shift,
arm_reg rd,
arm_reg rm,
int amt)
{
return arm_encode(cond, s + (arm_mov << 1) + (0 << 5), 0, rd,
rm + (0 << 4) + (shift << 5) + (amt << 7));
}

int __sll(arm_cond_t cond, arm_reg rd, arm_reg rm, arm_reg rs)
{
return arm_encode(cond, 0 + (arm_mov << 1) + (0 << 5), 0, rd,
rm + (1 << 4) + (0 << 5) + (rs << 8));
}

int __sll_amt(arm_cond_t cond,
int s,
shfit_type shift,
arm_reg rd,
arm_reg rm,
int amt)
{
return arm_encode(cond, s + (arm_mov << 1) + (0 << 5), 0, rd,
rm + (0 << 4) + (shift << 5) + (amt << 7));
}

int __add_i(arm_cond_t cond, arm_reg rd, arm_reg rs, int imm)
{
if (imm >= 0)
Expand Down Expand Up @@ -288,6 +320,11 @@ int __cmp_r(arm_cond_t cond, arm_reg r1, arm_reg r2)
return __mov(cond, 0, arm_cmp, 1, r1, 0, r2);
}

int __cmp_i(arm_cond_t cond, arm_reg rn, int imm)
{
return __mov(cond, 1, arm_cmp, 1, rn, 0, imm);
}

int __teq(arm_reg rd)
{
return __mov(__AL, 1, arm_teq, 1, rd, 0, 0);
Expand Down
2 changes: 1 addition & 1 deletion src/defs.h
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Expand Up @@ -25,7 +25,7 @@
#define MAX_BB_DOM_SUCC 64
#define MAX_GLOBAL_IR 256
#define MAX_LABEL 4096
#define MAX_SOURCE 278528
#define MAX_SOURCE 327680
#define MAX_CODE 262144
#define MAX_DATA 262144
#define MAX_SYMTAB 65536
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1 change: 1 addition & 0 deletions src/globals.c
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Expand Up @@ -132,6 +132,7 @@ int find_trie(trie_t *trie, char *name)
/* options */

int dump_ir = 0;
int hard_mul_div = 0;

/**
* find_type() - Find the type by the given name.
Expand Down
6 changes: 5 additions & 1 deletion src/main.c
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Expand Up @@ -51,6 +51,8 @@ int main(int argc, char *argv[])
for (int i = 1; i < argc; i++) {
if (!strcmp(argv[i], "--dump-ir"))
dump_ir = 1;
else if (!strcmp(argv[i], "+m"))
hard_mul_div = 1;
else if (!strcmp(argv[i], "--no-libc"))
libc = 0;
else if (!strcmp(argv[i], "-o")) {
Expand All @@ -66,7 +68,9 @@ int main(int argc, char *argv[])

if (!in) {
printf("Missing source file!\n");
printf("Usage: shecc [-o output] [--dump-ir] [--no-libc] <input.c>\n");
printf(
"Usage: shecc [-o output] [+m] [--dump-ir] [--no-libc] "
"<input.c>\n");
return -1;
}

Expand Down
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