Skip to content

emmalloc: use __heap_end instead of sbrk(0) #462

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Jan 10, 2024
Merged

emmalloc: use __heap_end instead of sbrk(0) #462

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
11 changes: 8 additions & 3 deletions emmalloc/emmalloc.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,7 @@

// Defind by the linker to have the address of the start of the heap.
extern unsigned char __heap_base;
extern unsigned char __heap_end;

// Behavior of right shifting a signed integer is compiler implementation defined.
static_assert((((int32_t)0x80000000U) >> 31) == -1, "This malloc implementation requires that right-shifting a signed integer produces a sign-extending (arithmetic) shift!");
Expand Down Expand Up @@ -545,9 +546,13 @@ static bool claim_more_memory(size_t numBytes)
// If this is the first time we're called, see if we can use
// the initial heap memory set up by wasm-ld.
if (!listOfAllRegions) {
unsigned char *heap_end = sbrk(0);
if (numBytes <= (size_t)(heap_end - &__heap_base)) {
startPtr = &__heap_base;
unsigned char *heap_base = &__heap_base;
unsigned char *heap_end = &__heap_end;
if (heap_end < heap_base) {
__builtin_trap();
}
if (numBytes <= (size_t)(heap_end - heap_base)) {
startPtr = heap_base;
endPtr = heap_end;
break;
}
Expand Down