Problem 686

Powers of two with leading digits 123: p(123, 678910).

View problem on Project Euler

Performance comparison

Flow source

# Project Euler 686
# Powers of two with leading digits 123: p(123, 678910).

extern {
    function log(x: f64) -> f64
    function floor(x: f64) -> f64
}

function main() -> i32 {
    let L: i64 = 123
    let n: i64 = 678910
    let digits: f64 = 3.0
    let lower: f64 = log(L as f64) / log(10.0) - (digits - 1.0)
    let upper: f64 = log((L + 1) as f64) / log(10.0) - (digits - 1.0)
    let cons: f64 = log(2.0) / log(10.0)
    let mut count: i64 = 0
    let mut j: i64 = 0
    while count != n {
        j = j + 1
        let temp: f64 = (j as f64) * cons
        let frac: f64 = temp - floor(temp)
        if frac > lower && frac < upper {
            count = count + 1
        }
    }
    printf("%lld\n", j)
    return 0
}

Generated C

#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* Flow runtime helpers */
typedef struct flow_temp_node { struct flow_temp_node* next; } flow_temp_node;
static flow_temp_node* flow_temp_head = NULL;
static int flow_temp_atexit_set = 0;
__attribute__((unused)) static void flow_temp_free_all(void) {
    while (flow_temp_head) {
        flow_temp_node* n = flow_temp_head;
        flow_temp_head = n->next;
        free(n);
    }
}
__attribute__((unused)) static void* flow_temp_alloc(size_t nbytes) {
    flow_temp_node* node = (flow_temp_node*)malloc(sizeof(flow_temp_node) + nbytes);
    if (!node) return NULL;
    node->next = flow_temp_head;
    flow_temp_head = node;
    if (!flow_temp_atexit_set) {
        flow_temp_atexit_set = 1;
        atexit(flow_temp_free_all);
    }
    return (void*)(node + 1);
}
#ifndef FLOW_DIAG
#define FLOW_DIAG(msg) fprintf(stderr, "%s", (msg))
#endif
#ifndef FLOW_LOG
#define FLOW_LOG(fmt, ...) printf(fmt, __VA_ARGS__)
#endif
#ifndef FLOW_LOG_EMPTY
#define FLOW_LOG_EMPTY(fmt) printf(fmt)
#endif
static char* flow_strcat(const char* a, const char* b) {
    size_t la = strlen(a ? a : ""), lb = strlen(b ? b : "");
    char* r = (char*)flow_temp_alloc(la + lb + 1);
    if (!r) return NULL;
    if (la) memcpy(r, a, la);
    if (lb) memcpy(r + la, b, lb);
    r[la + lb] = '\0';
    return r;
}

#define __flow_in_arr(arr, val) __extension__ ({ \
    int _found = 0; \
    size_t _n = sizeof(arr)/sizeof((arr)[0]); \
    for (size_t _i = 0; _i < _n; _i++) { \
        if ((arr)[_i] == (val)) { _found = 1; break; } \
    } _found; })

/* Unified fault handler (MISRA #279) — override with -DFLOW_FAULT_HANDLER=fn */
#ifndef FLOW_FAULT_HANDLER
__attribute__((unused)) static inline void flow_fault_handler(const char* msg) {
    fprintf(stderr, "flow: %s\n", msg ? msg : "fault");
    abort();
#if defined(__GNUC__) || defined(__clang__)
    __builtin_unreachable();
#endif
}
#else
#define flow_fault_handler FLOW_FAULT_HANDLER
#endif
#define flow_div_by_zero_handler() flow_fault_handler("division by zero")
#define flow_shift_ub_handler() flow_fault_handler("invalid shift (amount out of range or left-shift of negative)")

#ifndef FLOW_CHECKED_DIV
#define FLOW_CHECKED_DIV(L, R) (((R) != 0) ? ((L) / (R)) : (flow_div_by_zero_handler(), (L) * 0))
#endif
#ifndef FLOW_CHECKED_MOD
#define FLOW_CHECKED_MOD(L, R) (((R) != 0) ? ((L) % (R)) : (flow_div_by_zero_handler(), (L) * 0))
#endif
#ifndef FLOW_CHECKED_SHL
#define FLOW_CHECKED_SHL(L, R) ((((R) >= 0) && ((unsigned long long)(R) < (sizeof(L) * 8ull)) && ((L) >= 0)) ? ((L) << (R)) : (flow_shift_ub_handler(), (L) * 0))
#endif
#ifndef FLOW_CHECKED_SHR
#define FLOW_CHECKED_SHR(L, R) ((((R) >= 0) && ((unsigned long long)(R) < (sizeof(L) * 8ull))) ? ((L) >> (R)) : (flow_shift_ub_handler(), (L) * 0))
#endif

#include <math.h>

void* _ui_state = NULL;

static inline float i32_to_f32(int32_t v) { return (float)v; }

/* Host stub for @gpu kernels (device codegen replaces this). */
static inline int32_t gpu_thread_id(void) { return 0; }

int32_t main(void);



int32_t main(void) {
    int64_t L = 123;
    int64_t n = 678910;
    double digits = 3.0;
    double lower = ((log(((double)(L))) / log(10.0)) - (digits - 1.0));
    double upper = ((log(((double)((L + 1)))) / log(10.0)) - (digits - 1.0));
    double cons = (log(2.0) / log(10.0));
    int64_t count = 0;
    int64_t j = 0;
    while (count != n) {
        j = (j + 1);
        double temp = (((double)(j)) * cons);
        double frac = (temp - floor(temp));
        if ((frac > lower && frac < upper)) {
            count = (count + 1);
        }
    }
    printf("%lld\n", j);
    return 0;
}

Generated MLIR

module {
  llvm.func @printf(!llvm.ptr, ...) -> i32
  llvm.mlir.global internal constant @str_0("%lld\n\00") {addr_space = 0 : i32} : !llvm.array<6 x i8>
  func.func private @log(f64) -> f64
  func.func private @floor(f64) -> f64
  func.func @main() -> i32 {
    %0 = arith.constant 123 : i32
    %1 = arith.extsi %0 : i32 to i64
    %2 = arith.constant 678910 : i32
    %3 = arith.extsi %2 : i32 to i64
    %4 = arith.constant 3.0 : f32
    %5 = arith.extf %4 : f32 to f64
    %6 = arith.sitofp %1 : i64 to f64
    %7 = math.log %6 : f64
    %8 = arith.constant 10.0 : f32
    %9 = math.log %8 : f32
    %10 = arith.divf %7, %9 : f64
    %11 = arith.constant 1.0 : f32
    %13 = arith.extf %11 : f32 to f64
    %12 = arith.subf %5, %13 : f64
    %14 = arith.subf %10, %12 : f64
    %15 = arith.constant 1 : i32
    %17 = arith.extsi %15 : i32 to i64
    %16 = arith.addi %1, %17 : i64
    %18 = arith.sitofp %16 : i64 to f64
    %19 = math.log %18 : f64
    %20 = arith.constant 10.0 : f32
    %21 = math.log %20 : f32
    %22 = arith.divf %19, %21 : f64
    %23 = arith.constant 1.0 : f32
    %25 = arith.extf %23 : f32 to f64
    %24 = arith.subf %5, %25 : f64
    %26 = arith.subf %22, %24 : f64
    %27 = arith.constant 2.0 : f32
    %28 = math.log %27 : f32
    %29 = arith.constant 10.0 : f32
    %30 = math.log %29 : f32
    %31 = arith.divf %28, %30 : f64
    %32 = arith.constant 0 : i32
    %33 = arith.extsi %32 : i32 to i64
    %34 = llvm.mlir.constant(1 : i64) : i64
    %35 = llvm.alloca %34 x i64 : (i64) -> !llvm.ptr
    llvm.store %33, %35 : i64, !llvm.ptr
    %36 = arith.constant 0 : i32
    %37 = arith.extsi %36 : i32 to i64
    %38 = llvm.mlir.constant(1 : i64) : i64
    %39 = llvm.alloca %38 x i64 : (i64) -> !llvm.ptr
    llvm.store %37, %39 : i64, !llvm.ptr
    cf.br ^bb0
    ^bb0:
    %40 = llvm.load %35 : !llvm.ptr -> i64
    %41 = arith.cmpi ne, %40, %3 : i64
    cf.cond_br %41, ^bb1, ^bb2
    ^bb1:
      %42 = llvm.load %39 : !llvm.ptr -> i64
      %43 = arith.constant 1 : i32
      %45 = arith.extsi %43 : i32 to i64
      %44 = arith.addi %42, %45 : i64
      llvm.store %44, %39 : i64, !llvm.ptr
      %46 = llvm.load %39 : !llvm.ptr -> i64
      %47 = arith.sitofp %46 : i64 to f64
      %48 = arith.mulf %47, %31 : f64
      %49 = func.call @floor(%48) : (f64) -> f64
      %50 = arith.subf %48, %49 : f64
      %51 = arith.cmpf ogt, %50, %14 : f64
      %52 = scf.if %51 -> (i1) {
        %53 = arith.cmpf olt, %50, %26 : f64
        scf.yield %53 : i1
      } else {
        %54 = arith.constant false
        scf.yield %54 : i1
      }
      cf.cond_br %52, ^bb3, ^bb4
      ^bb3:
        %55 = llvm.load %35 : !llvm.ptr -> i64
        %56 = arith.constant 1 : i32
        %58 = arith.extsi %56 : i32 to i64
        %57 = arith.addi %55, %58 : i64
        llvm.store %57, %35 : i64, !llvm.ptr
        cf.br ^bb5
      ^bb4:
        cf.br ^bb5
      ^bb5:
      cf.br ^bb0
    ^bb2:
    %59 = llvm.mlir.addressof @str_0 : !llvm.ptr
    %60 = llvm.load %39 : !llvm.ptr -> i64
    %61 = llvm.call @printf(%59, %60) vararg(!llvm.func<i32 (ptr, ...)>) : (!llvm.ptr, i64) -> i32
    %62 = arith.constant 0 : i32
    func.return %62 : i32
  }
}