improved pu2 (vm speed ~1GHz on 1.8GHz cpu), reduced code emission, added another compile flag

1 files changed, 150 insertions, 97 deletions

diff --git a/pu2/pu2.c b/pu2/pu2.c
index 6121d8b..d1f6fe1 100644
--- a/pu2/pu2.c
+++ b/pu2/pu2.c
@@ -1,7 +1,13 @@
 #define _POSIX_C_SOURCE 200809L
 #include "pu2.out.c"
+//
+#include <errno.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/time.h>
 #include <time.h>
+#include <unistd.h>
 
 typedef char *string;
 
@@ -87,7 +93,7 @@ long powi(long x, unsigned n) {
         p *= p, n /= 2;
     }
 
-    return r;
+    return p == 0 ? 0 : r;
 }
 
 emu() {
@@ -163,9 +169,9 @@ skip_space(string *I) {
 // IR parser for pu2's as2
 // clang-format off
 struct {
-    int hlt, imm, lod, str, swp, add, sub, and, not, acc, a2u, u2a, b2u, u2b;
+    int hlt, imm, lod, str, swp, add, sub, and, not, acc, a2u, u2a, b2u, u2b, nop, cb1, cb2, cb3, cb4;
 } opcode = {
-    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
+    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18
 };
 // clang-format on
 
@@ -194,16 +200,6 @@ clean_slice_ref(slice *val) { free(val->ref); }
 
 #define static_len(G) (sizeof(G) / sizeof((G)[ 0 ]))
 
-#define emit(OP, VAL)                                                                              \
-    ({                                                                                             \
-        *Code++ = (OP);                                                                            \
-        *Code++ = (VAL);                                                                           \
-    })
-#define store()                                                                                    \
-    ({                                                                                             \
-        emit(opcode.acc, 1);                                                                       \
-        emit(opcode.str, 0);                                                                       \
-    })
 #define run_err(result, ...)                                                                       \
     ({                                                                                             \
         ERR_code = init_I;                                                                         \
@@ -262,34 +258,15 @@ clean_slice_ref(slice *val) { free(val->ref); }
        value;                                                                                      \
     })
 
-#define op(mode)   emit(opcode.mode, 0)
-#define swap()     emit(opcode.swp, 0)
-#define imm(value) emit(opcode.imm, value)
-#define load()     emit(opcode.lod, 0)
-#define imm_in_mem(__mem, __imm)                                                                   \
-    ({                                                                                             \
-        imm(__imm);                                                                                \
-        swap();                                                                                    \
-        imm(__mem);                                                                                \
-        store();                                                                                   \
-    })
-#define mov_mem_mem(__mem1, __mem2)                                                                \
-    ({                                                                                             \
-        imm(__mem2);                                                                               \
-        swap();                                                                                    \
-        load();                                                                                    \
-        swap();                                                                                    \
-        imm(__mem1);                                                                               \
-        store();                                                                                   \
-    })
-#define mem_in_a(__mem)                                                                            \
-    ({                                                                                             \
-        op(b2u);                                                                                   \
-        imm(__mem);                                                                                \
-        swap();                                                                                    \
-        load();                                                                                    \
-        op(u2b);                                                                                   \
-    })
+// #define emit(OP, VAL)               (*Code++ = (OP), *Code++ = (VAL))
+#define store()                     (emit(opcode.acc, 1), emit(opcode.str, 0))
+#define op(mode)                    emit(opcode.mode, 0)
+#define swap()                      emit(opcode.swp, 0)
+#define imm(value)                  emit(opcode.imm, value)
+#define load()                      emit(opcode.lod, 0)
+#define imm_in_mem(__mem, __imm)    (imm(__mem), emit(opcode.cb3, __imm))
+#define mov_mem_mem(__mem1, __mem2) (imm(__mem1), emit(opcode.cb4, __mem2))
+#define mem_in_a(__mem)             emit(opcode.cb2, __mem)
 #define perform_op(operation)                                                                      \
     ({                                                                                             \
         mem_in_a(mem2_index);                                                                      \
@@ -306,6 +283,13 @@ string ERR;
 string ERR_code;
 int   *Code = &m[ 4000 ];
 int   *Data = &m[ static_len(m) - 1 ]; // grows downwards
+
+__attribute__((always_inline)) emit(int op, int val) {
+    *Code++ = op;
+    *Code++ = val;
+}
+
+bool has_jump_warned = false;
 _ir2(string I, macro macros[ 1 << 9 ]) {
     string init_I = I;
     ERR           = "all good";
@@ -328,6 +312,12 @@ _ir2(string I, macro macros[ 1 << 9 ]) {
             checkskip('=', "expected assigment after memory blob (hint: only +-&! are supported)");
             skip_space(&I);
 
+            if (mem_index == 7 && !has_jump_warned) {
+                has_jump_warned = true;
+                printf("\nwarn: writing to memory index 7 is equivalent to a jump\n");
+                printf("      if this behavior is intended, use the jump blob instead.\n\n");
+            }
+
             if (*I == '@') {
                 I++;
                 if (!isdigit(*I)) { run_err(I, "expected a digit after @"); }
@@ -360,6 +350,8 @@ _ir2(string I, macro macros[ 1 << 9 ]) {
                     swap();
                     mem_in_a(mem_index);
                     emit(opcode.add, 0);
+                    swap();
+                    imm(mem_index);
                     store();
                 } else if (extra_op == '-') {
                     imm(imm);
@@ -633,12 +625,12 @@ _ir2(string I, macro macros[ 1 << 9 ]) {
 }
 
 ir2(string I) {
-    macro macros[ 1 << 9 ] = {0};
+    macro macros[ 1 << 9 ] = { 0 };
     _ir2(I, macros);
 }
 
-string op_names[] = { "hlt", "imm", "lod", "str", "swp", "add", "sub",
-                      "and", "not", "acc", "a2u", "u2a", "b2u", "u2b" };
+string op_names[] = { "hlt", "imm", "lod", "str", "swp", "add", "sub", "and", "not", "acc",
+                      "a2u", "u2a", "b2u", "u2b", "nop", "cb1", "cb2", "cb3", "cb4" };
 
 unsigned long long rdtsc(void) {
     unsigned hi, lo;
@@ -646,6 +638,14 @@ unsigned long long rdtsc(void) {
     return ((unsigned long long) hi << 32) | lo;
 }
 
+clock_t ntime() {
+    struct timespec t;
+    clock_gettime(CLOCK_MONOTONIC_RAW, &t);
+
+    return t.tv_nsec + t.tv_sec * 1e9;
+}
+
+// bench: measure using clock()
 double bench_cycle(int instr) {
     int i;
     for (i = 0; i < S - 2; i += 2) {
@@ -658,15 +658,29 @@ double bench_cycle(int instr) {
     m[ 7 ] = 0;
     c      = 0;
 
-    clock_t start = clock();
+    clock_t start  = ntime();
+    size_t  wstart = rdtsc();
     pu2();
-    clock_t end = clock();
-
-    double seconds = (double) (end - start) / CLOCKS_PER_SEC;
-    printf("time: %.6f s\n", seconds);
-    return (double) m[ 7 ] / seconds / 1e6;
+    size_t  wend = rdtsc();
+    clock_t end  = ntime();
+
+    double nanoseconds  = (end - start);
+    double inst_count   = (double) m[ 7 ] / 2;
+    double insts_per_ns = inst_count / nanoseconds;
+    double insts_per_s  = insts_per_ns * 1e9;
+
+    printf(
+        "%-8s | time: %.3fms | insts: %.0f (%li real) | ips: %.3fM inst/s\n",
+        op_names[ instr ],
+        nanoseconds / 1000000,
+        inst_count,
+        end - start,
+        insts_per_ns * 1e3);
+
+    return insts_per_s / 1e6; // return M inst/s
 }
 
+// bench2: measure using rdtsc
 double bench2_cycle(int instr) {
     unsigned long long start, end;
     double             vminst_count, cpu_cycles;
@@ -681,58 +695,116 @@ double bench2_cycle(int instr) {
     c          = 0;
     start      = rdtsc();
     pu2();
-    end          = rdtsc();
-    cpu_cycles   = (double) (end - start);
-    vminst_count = (double) m[ 7 ];
-    printf("pu2/real: %f\n", cpu_cycles / vminst_count);
-    return cpu_cycles / vminst_count;
+    end                    = rdtsc();
+    cpu_cycles             = (double) (end - start);
+    vminst_count           = (double) m[ 7 ] / 2;
+    double cycles_per_inst = cpu_cycles / vminst_count;
+
+    printf(
+        "%-6s | cycles/inst: %8.3f | cycles: %14.0f | insts: %12.0f\n",
+        op_names[ instr ],
+        cycles_per_inst,
+        cpu_cycles,
+        vminst_count);
+    return cycles_per_inst;
+}
+
+sleep_nano(int nanoseconds) {
+    struct timespec req = { 0 };
+    req.tv_sec          = nanoseconds / 1000000000L; // Whole seconds
+    req.tv_nsec         = nanoseconds % 1000000000L; // Remaining nanoseconds
+
+    // nanosleep might be interrupted, so loop until it completes
+    while (nanosleep(&req, &req) == -1 && errno == EINTR) {
+        continue; // Continue with remaining time if interrupted
+    }
 }
 
-benchmark(double (*target)(int)) {
-    double results[ 13 ];
+[[clang::always_inline]] sleep_micro(int microseconds) { sleep_nano(microseconds * 1e3); }
+[[clang::always_inline]] sleep_milli(int milliseconds) { sleep_nano(milliseconds * 1e6); }
+
+// benchmark: run target for all opcodes and print summary
+benchmark(double (*target)(int), const char *mode_label) {
+    double results[ 19 ];
     double sum   = 0;
     int    count = 0;
     int    i;
-    for (i = 1; i < 14; i++) {
-        printf("running: %s\n", op_names[ i ]);
+
+    printf("\n=== pu2 benchmark (%s) ===\n", mode_label);
+    printf("op     | result details\n");
+    printf("---------------------------------------------\n");
+
+    for (i = 1; i < 19; i++) {
+        // printf("running: %s\n", op_names[ i ]);
         results[ i ] = target(i);
         sum += results[ i ];
         count++;
     }
     sum /= count;
 
-    unsigned long long start, end;
-    start = rdtsc();
-    sleep(1);
-    end = rdtsc();
-
-    float clock_speed = (end - start) / 1e6;
-    printf("results sum: %f\n", sum);
-    if (target == bench_cycle) {
-        printf("clock speed ~ %.6f MHz\n", clock_speed);
-        printf("instructions per cycle: %f\n", clock_speed / sum);
+    printf("---------------------------------------------\n");
+
+    size_t start = rdtsc();
+    sleep_milli(100);
+    size_t end = rdtsc();
+
+    double clock_speed_mhz = ((end - start) / 1e6) * 10;
+
+    if (strcmp(mode_label, "time") == 0) {
+        // printf("average   : %.3f M inst/s\n", sum);
+        printf("cpu clock      : ~%.3f MHz (measured via rdtsc & msleep(100))\n", clock_speed_mhz);
+        printf("vm clock (i/s) : %.3fMHz (ipn, higher is better)\n", sum);
+        // printf("estimated : %.3f cycles per instruction (cpi, lower is better)\n",
+        // clock_speed_mhz / sum);
+    } else {
+        // mode_label == "rdtsc"
+        printf("average cycles/inst : %.3f cycles\n", sum);
+        // printf("cpu clock      : ~%.3f MHz (measured via rdtsc & msleep(100))\n",
+        // clock_speed_mhz);
+        printf("estimated ipc       : %.3f (1 / cycles_per_inst, higher is better)\n", 1.0 / sum);
+        // printf("estimated cpi       : %.3f (cycles_per_inst, lower is better)\n", sum);
     }
+    printf("=== end benchmark ===\n\n");
 }
 
-long nstime() {
+nstime() {
     struct timespec ts;
     clock_gettime(CLOCK_MONOTONIC, &ts);
     return ts.tv_nsec;
 }
 
+volatile long out;
+
 main(int argc, char **argv) {
     if (argc == 1) {
         return printf(
             "\nusage:\n"
             "    %s <file_name>              open and compile ir2-compliant code\n"
-            "    %s --bench                  benchmark pu2\n\n",
+            "    %s benchmark                benchmark pu2 (two modes: time and rdtsc)\n\n",
             argv[ 0 ],
             argv[ 0 ]);
     }
 
-    if (strcmp(argv[ 1 ], "--bench") == 0) {
-        benchmark(bench_cycle);
-        benchmark(bench2_cycle);
+    if (strcmp(argv[ 1 ], "benchmark") == 0) {
+        benchmark(bench_cycle, "time");
+
+        const long         N   = S / 2; // printably the same insts you report
+        long               sum = 0;
+        unsigned           aux;
+        unsigned long long t0 = rdtsc();
+        int                C;
+        for (C = 0; C < N; ++C) {
+            sum += 1;
+            __asm__ volatile("");
+        }
+        unsigned long long t1 = rdtsc();
+        out                   = sum; // single volatile write to make sum observable
+        printf(
+            "N=%llu cycles=%llu cycles/iter=%.6f\n",
+            (unsigned long long) N,
+            (unsigned long long) (t1 - t0),
+            (t1 - t0) / (double) N);
+        // benchmark(bench2_cycle, "rdtsc");
         exit(0);
     }
 
@@ -745,35 +817,16 @@ main(int argc, char **argv) {
     }
 
     size_t o_size;
-    long before = nstime();
-    long cycles_bef = rdtsc();
+    long   before     = nstime();
+    long   cycles_bef = rdtsc();
     ir2(contents);
     long cycles_aft = rdtsc();
-    long after = nstime();
-    m[ 7 ] = 4000;
+    long after      = nstime();
+    m[ 7 ]          = 4000;
 
-    // fprintf(stderr, "assembly took %li nanoseconds (%li cycles)\n", (after - before), (cycles_aft - cycles_bef));
     free(contents);
 
     size_t res_size = Code - &m[ 4000 ];
-    // --- BYTES PRINTING ---
-
-    // for(i = 0; i < res_size; i++) {
-    //     printf("%X%X ", m[4000+i]>>4, m[4000+i]&0b1111);
-    //     if(i % 8 == 7) printf("\n");
-    // }
-    // fflush(stdout);
-    // printf("\n\n");
-
-    // --- OPCODES PRINTING ---
-
-    // for (i = 0; i < res_size; i++) {
-    //     int op   = m[ 4000 + i++ ];
-    //     int data = m[ 4000 + i ];
-
-    //     printf("%s(%i);\n", op_names[ op ], data);
-    // }
-    // printf("\n\n");
 
     emu();
 }