117 lines
3.3 KiB
V
117 lines
3.3 KiB
V
[has_globals]
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module builtin
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// With -prealloc, V calls libc's malloc to get chunks, each at least 16MB
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// in size, as needed. Once a chunk is available, all malloc() calls within
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// V code, that can fit inside the chunk, will use it instead, each bumping a
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// pointer, till the chunk is filled. Once a chunk is filled, a new chunk will
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// be allocated by calling libc's malloc, and the process continues.
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// Each new chunk has a pointer to the old one, and at the end of the program,
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// the entire linked list of chunks is freed.
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// The goal of all this is to amortize the cost of calling libc's malloc,
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// trading higher memory usage for a compiler (or any single threaded batch
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// mode program), for a ~8-10% speed increase.
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// Note: `-prealloc` is NOT safe to be used for multithreaded programs!
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// size of the preallocated chunk
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const prealloc_block_size = 16 * 1024 * 1024
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__global g_memory_block &VMemoryBlock
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[heap]
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struct VMemoryBlock {
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mut:
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id int
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cap isize
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start &byte = 0
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previous &VMemoryBlock = 0
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remaining isize
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current &u8 = 0
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mallocs int
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}
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[unsafe]
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fn vmemory_block_new(prev &VMemoryBlock, at_least isize) &VMemoryBlock {
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mut v := unsafe { &VMemoryBlock(C.calloc(1, sizeof(VMemoryBlock))) }
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if unsafe { prev != 0 } {
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v.id = prev.id + 1
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}
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v.previous = prev
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block_size := if at_least < prealloc_block_size { prealloc_block_size } else { at_least }
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v.start = unsafe { C.malloc(block_size) }
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v.cap = block_size
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v.remaining = block_size
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v.current = v.start
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return v
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}
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[unsafe]
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fn vmemory_block_malloc(n isize) &byte {
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unsafe {
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if g_memory_block.remaining < n {
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g_memory_block = vmemory_block_new(g_memory_block, n)
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}
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mut res := &u8(0)
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res = g_memory_block.current
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g_memory_block.remaining -= n
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g_memory_block.mallocs++
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g_memory_block.current += n
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return res
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}
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}
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/////////////////////////////////////////////////
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[unsafe]
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fn prealloc_vinit() {
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unsafe {
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g_memory_block = vmemory_block_new(voidptr(0), prealloc_block_size)
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$if !freestanding {
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C.atexit(prealloc_vcleanup)
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}
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}
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}
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[unsafe]
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fn prealloc_vcleanup() {
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$if prealloc_stats ? {
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// Note: we do 2 loops here, because string interpolation
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// in the first loop may still use g_memory_block
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// The second loop however should *not* allocate at all.
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mut nr_mallocs := i64(0)
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mut mb := g_memory_block
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for unsafe { mb != 0 } {
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nr_mallocs += mb.mallocs
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eprintln('> freeing mb.id: ${mb.id:3} | cap: ${mb.cap:7} | rem: ${mb.remaining:7} | start: ${voidptr(mb.start)} | current: ${voidptr(mb.current)} | diff: ${u64(mb.current) - u64(mb.start):7} bytes | mallocs: $mb.mallocs')
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mb = mb.previous
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}
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eprintln('> nr_mallocs: $nr_mallocs')
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}
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unsafe {
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for g_memory_block != 0 {
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C.free(g_memory_block.start)
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g_memory_block = g_memory_block.previous
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}
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}
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}
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[unsafe]
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fn prealloc_malloc(n isize) &byte {
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return unsafe { vmemory_block_malloc(n) }
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}
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[unsafe]
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fn prealloc_realloc(old_data &byte, old_size isize, new_size isize) &byte {
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new_ptr := unsafe { vmemory_block_malloc(new_size) }
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min_size := if old_size < new_size { old_size } else { new_size }
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unsafe { C.memcpy(new_ptr, old_data, min_size) }
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return new_ptr
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}
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[unsafe]
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fn prealloc_calloc(n isize) &byte {
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new_ptr := unsafe { vmemory_block_malloc(n) }
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unsafe { C.memset(new_ptr, 0, n) }
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return new_ptr
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}
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