/* ---------------------------------------------- *//* alloca.S */ #ifdef __leading_underscore# define _(s) _##s#else# define _(s) s#endif /* ---------------------------------------------- */#if defined __i386__ .globl _(alloca), _(__alloca)_(alloca):_(__alloca): pop %edx pop %eax add $3,%eax and $-4,%eax jz p3 #ifdef _WIN32p1: cmp $4096,%eax jb p2 test %eax,-4096(%esp) sub $4096,%esp sub $4096,%eax jmp p1p2:#endif sub %eax,%esp mov %esp,%eaxp3: push %edx push %edx ret /* ---------------------------------------------- */#elif defined __x86_64__ .globl _(alloca)_(alloca): pop %rdx#ifdef _WIN32 mov %rcx,%rax#else mov %rdi,%rax#endif add $15,%rax and $-16,%rax jz p3 #ifdef _WIN32p1: cmp $4096,%rax jb p2 test %rax,-4096(%rsp) sub $4096,%rsp sub $4096,%rax jmp p1p2:#endif sub %rax,%rsp mov %rsp,%raxp3: push %rdx ret /* ---------------------------------------------- */#elif defined __arm__ .globl _(alloca)_(alloca): rsb sp, r0, sp bic sp, sp, #7 mov r0, sp mov pc, lr /* ---------------------------------------------- */#elif defined __aarch64__ || defined __arm64__ .globl _(alloca)_(alloca):#ifdef __TINYC__ .int 0x91003c00 .int 0x927cec00#ifdef _WIN32 .int 0xb4000160 .int 0xd2820001 .int 0xeb01001f .int 0x540000c3 .int 0xcb2163e2 .int 0xf940005f .int 0xcb2163ff .int 0xcb010000 .int 0x17fffffa .int 0xb4000040#endif .int 0xcb2063ff .int 0x910003e0 .int 0xd65f03c0#else add x0, x0, #15 // Round up to 16-byte boundary and x0, x0, #-16 // Ensure 16-byte alignment#ifdef _WIN32 cbz x0, p100 // If size is 0, skip to return // Windows requires page-wise allocation with stack probing mov x1, #4096 // Page size = 4096 bytes p101: cmp x0, x1 // Compare remaining size with page size b.lo p102 // If less than page, jump to remainder // Probe first, then allocate sub x2, sp, x1 // Calculate guard page address (sp - 4096) ldr xzr, [x2] // Touch guard page FIRST sub sp, sp, x1 // THEN allocate the page sub x0, x0, x1 // Decrement remaining size b p101 // Continue loop p102: // Allocate remaining bytes (less than one page) cbz x0, p100 // If no remaining bytes, skip sub sp, sp, x0 // Allocate remaining space#else // Non-Windows: simple one-time allocation sub sp, sp, x0 // Allocate space on stack#endif p100: mov x0, sp // Return allocated address ret // Return to caller#endif /* ---------------------------------------------- */#elif defined __riscv .globl _(alloca)_(alloca): sub sp, sp, a0 addi sp, sp, -15 andi sp, sp, -16 add a0, sp, zero ret #endif
/* ---------------------------------------------- */
/* alloca.S */
#ifdef __leading_underscore
# define _(s) _##s
#else
# define _(s) s
#endif
/* ---------------------------------------------- */
#if defined __i386__
.globl _(alloca), _(__alloca)
_(alloca):
_(__alloca):
pop %edx
pop %eax
add $3,%eax
and $-4,%eax
jz p3
#ifdef _WIN32
p1:
cmp $4096,%eax
jb p2
test %eax,-4096(%esp)
sub $4096,%esp
sub $4096,%eax
jmp p1
p2:
#endif
sub %eax,%esp
mov %esp,%eax
p3:
push %edx
push %edx
ret
/* ---------------------------------------------- */
#elif defined __x86_64__
.globl _(alloca)
_(alloca):
pop %rdx
#ifdef _WIN32
mov %rcx,%rax
#else
mov %rdi,%rax
#endif
add $15,%rax
and $-16,%rax
jz p3
#ifdef _WIN32
p1:
cmp $4096,%rax
jb p2
test %rax,-4096(%rsp)
sub $4096,%rsp
sub $4096,%rax
jmp p1
p2:
#endif
sub %rax,%rsp
mov %rsp,%rax
p3:
push %rdx
ret
/* ---------------------------------------------- */
#elif defined __arm__
.globl _(alloca)
_(alloca):
rsb sp, r0, sp
bic sp, sp, #7
mov r0, sp
mov pc, lr
/* ---------------------------------------------- */
#elif defined __aarch64__ || defined __arm64__
.globl _(alloca)
_(alloca):
#ifdef __TINYC__
.int 0x91003c00
.int 0x927cec00
#ifdef _WIN32
.int 0xb4000160
.int 0xd2820001
.int 0xeb01001f
.int 0x540000c3
.int 0xcb2163e2
.int 0xf940005f
.int 0xcb2163ff
.int 0xcb010000
.int 0x17fffffa
.int 0xb4000040
#endif
.int 0xcb2063ff
.int 0x910003e0
.int 0xd65f03c0
#else
add x0, x0, #15 // Round up to 16-byte boundary
and x0, x0, #-16 // Ensure 16-byte alignment
#ifdef _WIN32
cbz x0, p100 // If size is 0, skip to return
// Windows requires page-wise allocation with stack probing
mov x1, #4096 // Page size = 4096 bytes
p101:
cmp x0, x1 // Compare remaining size with page size
b.lo p102 // If less than page, jump to remainder
// Probe first, then allocate
sub x2, sp, x1 // Calculate guard page address (sp - 4096)
ldr xzr, [x2] // Touch guard page FIRST
sub sp, sp, x1 // THEN allocate the page
sub x0, x0, x1 // Decrement remaining size
b p101 // Continue loop
p102:
// Allocate remaining bytes (less than one page)
cbz x0, p100 // If no remaining bytes, skip
sub sp, sp, x0 // Allocate remaining space
#else
// Non-Windows: simple one-time allocation
sub sp, sp, x0 // Allocate space on stack
#endif
p100:
mov x0, sp // Return allocated address
ret // Return to caller
#endif
/* ---------------------------------------------- */
#elif defined __riscv
.globl _(alloca)
_(alloca):
sub sp, sp, a0
addi sp, sp, -15
andi sp, sp, -16
add a0, sp, zero
ret
#endif