erikcorry

; ============================================================================
; __udivmodhi4_mul - 16 / 16 -> quotient and remainder, unsigned, -mmul version
; ============================================================================
;       a in r0, b in r1        ->      quotient in r0, remainder in r1
;
; Two arguments and a 32-bit result, so by isa/abi.s this owns r0, r1 and r5
; and must give back r2, r3 and r4.
; This version is picked when using -mmul, which means the CPU has mul and
; recip instructions.
;

erikcorry

00000000 <divmod>:
   0:   90 07           push    r7
   2:   53 0f           or      r7, r1, #0
   4:   28 51           mov     r1, #10
   6:   a7 cc 1c        br      eq, r7, r1, 25 <divmod+0x25>
   9:   33 39           clz     r1, r7
   b:   67 3d           shl     r5, r7, r1
   d:   c3 2d           recip   r5, r5, #0
   f:   70 0d           lsr     r5, r5, #1
  11:   54 7d           or      r5, r5, #0x8000

erikcorry

#include <stdint.h>

#define unlikely(x) __builtin_expect(!!(x), 0)
#define likely(x) __builtin_expect(!!(x), 1)

typedef struct {
  uint16_t div;
  uint16_t mod;
} result;

erikcorry

BUZZY
IMMIX
COCCO
QAJAQ
TRATT
KHAPH
GNASH
SWASH
FLASH
LEASH

erikcorry

COCCO
PUPPY
WRING
LABEL
LEMMA
LEADS
LEASE
LEAST
LEASH

erikcorry

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erikcorry

 1958cc0:       43 0f be 5c 0c 01       movsbl 0x1(%r12,%r9,1),%ebx       // ebx = load small int
 1958cc6:       49 8d 51 02             lea    0x2(%r9),%rdx              // rdx = next bytecode addr
 1958cca:       43 0f b6 74 0c 02       movzbl 0x2(%r12,%r9,1),%esi       // esi = peek at next bytecode
 1958cd0:       8d 04 1b                lea    (%rbx,%rbx,1),%eax         // eax = rbx * 2 (tag smi)
 1958cd3:       40 80 fe c1             cmp    $0xc1,%sil                 // is next bc star?  (Store accumulator in 'register'.
 1958cd7:       73 09                   jae    1958ce2 <Builtins_LdaSmiHandler+0x22>  // jmp if star
 1958cd9:       49 8b 0c f7             mov    (%r15,%rsi,8),%rcx         // add bytecode to r15, load next bytecode handler.
 1958cdd:       4c 8b ca                mov    %rdx,%r9                   // Update bytecode program counter
 1958ce0:       ff e1                   jmp    *%rcx                      // Dispatch to next handler
 1958ce2:       48 8b dd                mov    %rbp

erikcorry

#include <immintrin.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <sys/mman.h>

// Compile with clang++ -g -mavx512bw -mavx512f -o mask-test mask-test.cc

int main() {
  char* addr = (char*)mmap(0, 8192, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);

erikcorry

python3 ../../tools/run.py ./mksnapshot --turbo_instruction_scheduling --stress-turbo-late-spilling --target_os=linux --target_arch=x64 --embedded_src gen/embedded.S --predictable --no-use-ic --embedded_variant Default --random-seed 314159265 --startup_src gen/snapshot.cc --native-code-counters --concurrent-builtin-generation --concurrent-turbofan-max-threads=0 --verify-heap
=================================================================
==1412959==ERROR: AddressSanitizer: heap-use-after-free on address 0x75a4a36202c0 at pc 0x5c2e6e9dca2f bp 0x7ffece69cad0 sp 0x7ffece69cac8
READ of size 8 at 0x75a4a36202c0 thread T0
    #0 0x5c2e6e9dca2e in v8::internal::VirtualMemory::Free() src/utils/allocation.cc:286:52
    #1 0x5c2e6cec2c69 in v8::internal::CodeRange::Free() src/heap/code-range.cc:361:24
    #2 0x5c2e6cec2c69 in v8::internal::CodeRange::~CodeRange() src/heap/code-range.cc:93:27
    #3 0x5c2e6d66c7c6 in std::__Cr::default_delete<v8::internal::CodeRange>::operator()(v8::internal::CodeRange*) const third_p

erikcorry

clang_version = "20"
use_rtti = true
use_sysroot = false
v8_enable_pointer_compression_shared_cage = false
v8_enable_external_code_space = false
cppgc_enable_caged_heap = false
icu_use_data_file = false
# These are defines only relevant to Chromium not V8, no need to have them here.
use_aura = false
use_blink = false