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Merged
kripken merged 4 commits into from
Nov 21, 2023
Merged

emmalloc: Ask sbrk for aligned sizes #20759

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38a16e7
emmalloc: Ask sbrk for aligned sizes
kripken Nov 21, 2023
b81e2a3
typo
kripken Nov 21, 2023
ae7b0f6
Merge remote-tracking branch 'origin/main' into emmalloc.aligned-sbrk
kripken Nov 21, 2023
48faf4e
update code size
kripken Nov 21, 2023
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17 changes: 17 additions & 0 deletions system/lib/emmalloc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -486,6 +486,12 @@ static bool claim_more_memory(size_t numBytes)
validate_memory_regions();
#endif

// Make sure we send sbrk requests of aligned sizes. If we do not do that then
// it will not return contiguous regions, which leads to use creating more
// root regions below, inefficiently. (Note that we assume our alignment is
// identical to sbrk's, see the assumptions at the start of this file.)
numBytes = (size_t)ALIGN_UP(numBytes, MALLOC_ALIGNMENT);
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@sbc100 sbc100 Nov 21, 2023

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Is the cast needed here? numBytes is already size_t.. and I imagine that MALLOC_ALIGNMENT is too, no?

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@kripken kripken Nov 21, 2023

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The cast is needed as the output of the macro is a pointer,

emscripten/system/lib/emmalloc.c

Line 138 in b81e2a3

#define ALIGN_UP(ptr, alignment) ((uint8_t*)((((uintptr_t)(ptr)) + ((alignment)-1)) & ~((alignment)-1)))


// Claim memory via sbrk
uint8_t *startPtr = (uint8_t*)sbrk(numBytes);
if ((intptr_t)startPtr == -1)
Expand All @@ -510,6 +516,9 @@ static bool claim_more_memory(size_t numBytes)
uint8_t *previousSbrkEndAddress = listOfAllRegions ? listOfAllRegions->endPtr : 0;
if (startPtr == previousSbrkEndAddress)
{
#ifdef EMMALLOC_VERBOSE
MAIN_THREAD_ASYNC_EM_ASM(err('claim_more_memory: expanding previous'));
#endif
Region *prevEndSentinel = prev_region((Region*)startPtr);
assert(debug_region_is_consistent(prevEndSentinel));
assert(region_is_in_use(prevEndSentinel));
Expand All @@ -536,6 +545,9 @@ static bool claim_more_memory(size_t numBytes)
else
{
// Create a root region at the start of the heap block
#ifdef EMMALLOC_VERBOSE
MAIN_THREAD_ASYNC_EM_ASM(err('claim_more_memory: creating new root region'));
#endif
create_used_region(startPtr, sizeof(Region));

// Dynamic heap start region:
Expand Down Expand Up @@ -583,6 +595,11 @@ void emmalloc_blank_slate_from_orbit()
static void *attempt_allocate(Region *freeRegion, size_t alignment, size_t size)
{
ASSERT_MALLOC_IS_ACQUIRED();

#ifdef EMMALLOC_VERBOSE
MAIN_THREAD_ASYNC_EM_ASM(out('attempt_allocate(freeRegion=' + ptrToString($0) + ',alignment=' + Number($1) + ',size=' + Number($2) + ')'), freeRegion, alignment, size);
#endif

assert(freeRegion);
// Look at the next potential free region to allocate into.
// First, we should check if the free region has enough of payload bytes contained
Expand Down
8 changes: 4 additions & 4 deletions test/code_size/embind_val_wasm.json
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Expand Up @@ -3,8 +3,8 @@
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8 changes: 4 additions & 4 deletions test/code_size/hello_wasm_worker_wasm.json
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Expand Up @@ -3,8 +3,8 @@
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8 changes: 4 additions & 4 deletions test/code_size/hello_webgl2_wasm.json
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Expand Up @@ -3,8 +3,8 @@
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8 changes: 4 additions & 4 deletions test/code_size/hello_webgl2_wasm2js.json
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@@ -1,10 +1,10 @@
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8 changes: 4 additions & 4 deletions test/code_size/hello_webgl_wasm.json
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Expand Up @@ -3,8 +3,8 @@
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8 changes: 4 additions & 4 deletions test/code_size/hello_webgl_wasm2js.json
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@@ -1,10 +1,10 @@
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