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ext/bcmath: If size of BC_VECTOR array is within 64 bytes, stack area is now used (#18065)

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This commit is contained in:
Saki Takamachi
2025-03-15 08:43:43 +09:00
committed by GitHub
parent 843d2a9b5f
commit 6b6fde9098
4 changed files with 34 additions and 11 deletions
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2
NEWS
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@@ -5,6 +5,8 @@ PHP NEWS
- BCMath:
. Simplify `bc_divide()` code. (SakiTakamachi)
. If the result is 0, n_scale is set to 0. (SakiTakamachi)
. If size of BC_VECTOR array is within 64 bytes, stack area is now used.
(SakiTakamachi)
- CLI:
. Add --ini=diff to print INI settings changed from the builtin default.

14
ext/bcmath/libbcmath/src/div.c
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@@ -260,7 +260,15 @@ static void bc_do_div(
size_t quot_arr_size = numerator_arr_size - divisor_arr_size + 1;
size_t quot_real_arr_size = MIN(quot_arr_size, (quot_size + BC_VECTOR_SIZE - 1) / BC_VECTOR_SIZE);
BC_VECTOR *numerator_vectors = safe_emalloc(numerator_arr_size + divisor_arr_size + quot_arr_size, sizeof(BC_VECTOR), 0);
BC_VECTOR stack_vectors[BC_STACK_VECTOR_SIZE];
size_t allocation_arr_size = numerator_arr_size + divisor_arr_size + quot_arr_size;
BC_VECTOR *numerator_vectors;
if (allocation_arr_size <= BC_STACK_VECTOR_SIZE) {
numerator_vectors = stack_vectors;
} else {
numerator_vectors = safe_emalloc(allocation_arr_size, sizeof(BC_VECTOR), 0);
}
BC_VECTOR *divisor_vectors = numerator_vectors + numerator_arr_size;
BC_VECTOR *quot_vectors = divisor_vectors + divisor_arr_size;
@@ -302,7 +310,9 @@ static void bc_do_div(
quot_vectors[i] /= BASE;
}
efree(numerator_vectors);
if (allocation_arr_size > BC_STACK_VECTOR_SIZE) {
efree(numerator_vectors);
}
}
static inline void bc_divide_by_one(bc_num numerator, bc_num *quot, size_t quot_scale)

3
ext/bcmath/libbcmath/src/private.h
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@@ -64,6 +64,9 @@
# define BC_LITTLE_ENDIAN 1
#endif
/* 64-bytes for 64-bit */
#define BC_STACK_VECTOR_SIZE 8
/*
* Adding more than this many times may cause uint32_t/uint64_t to overflow.
* Typically this is 1844 for 64bit and 42 for 32bit.

26
ext/bcmath/libbcmath/src/recmul.c
View File

@@ -149,15 +149,21 @@ static void bc_standard_mul(bc_num n1, size_t n1len, bc_num n2, size_t n2len, bc
size_t n2_arr_size = (n2len + BC_VECTOR_SIZE - 1) / BC_VECTOR_SIZE;
size_t prod_arr_size = (prodlen + BC_VECTOR_SIZE - 1) / BC_VECTOR_SIZE;
/*
* let's say that N is the max of n1len and n2len (and a multiple of BC_VECTOR_SIZE for simplicity),
* then this sum is <= N/BC_VECTOR_SIZE + N/BC_VECTOR_SIZE + N/BC_VECTOR_SIZE + N/BC_VECTOR_SIZE - 1
* which is equal to N - 1 if BC_VECTOR_SIZE is 4, and N/2 - 1 if BC_VECTOR_SIZE is 8.
*/
BC_VECTOR *buf = safe_emalloc(n1_arr_size + n2_arr_size + prod_arr_size, sizeof(BC_VECTOR), 0);
BC_VECTOR stack_vectors[BC_STACK_VECTOR_SIZE];
size_t allocation_arr_size = n1_arr_size + n2_arr_size + prod_arr_size;
BC_VECTOR *n1_vector = buf;
BC_VECTOR *n2_vector = buf + n1_arr_size;
BC_VECTOR *n1_vector;
if (allocation_arr_size <= BC_STACK_VECTOR_SIZE) {
n1_vector = stack_vectors;
} else {
/*
* let's say that N is the max of n1len and n2len (and a multiple of BC_VECTOR_SIZE for simplicity),
* then this sum is <= N/BC_VECTOR_SIZE + N/BC_VECTOR_SIZE + N/BC_VECTOR_SIZE + N/BC_VECTOR_SIZE - 1
* which is equal to N - 1 if BC_VECTOR_SIZE is 4, and N/2 - 1 if BC_VECTOR_SIZE is 8.
*/
n1_vector = safe_emalloc(allocation_arr_size, sizeof(BC_VECTOR), 0);
}
BC_VECTOR *n2_vector = n1_vector + n1_arr_size;
BC_VECTOR *prod_vector = n2_vector + n2_arr_size;
for (i = 0; i < prod_arr_size; i++) {
@@ -188,7 +194,9 @@ static void bc_standard_mul(bc_num n1, size_t n1len, bc_num n2, size_t n2len, bc
bc_mul_finish_from_vector(prod_vector, prod_arr_size, prodlen, prod);
efree(buf);
if (allocation_arr_size > BC_STACK_VECTOR_SIZE) {
efree(n1_vector);
}
}
/** This is bc_standard_mul implementation for square */