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Simplify & expand c_readstr

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c_readstr only operated on integer modes.  It worked by reading
the source string into an array of HOST_WIDE_INTs, converting
that array into a wide_int, and from there to an rtx.

It's simpler to do this by building a target memory image and
using native_decode_rtx to convert that memory image into an rtx.
It avoids all the endianness shenanigans because both the string and
native_decode_rtx follow target memory order.  It also means that the
function can handle all fixed-size modes, which simplifies callers
and allows vector modes to be used more widely.

gcc/
	* builtins.h (c_readstr): Take a fixed_size_mode rather than a
	scalar_int_mode.
	* builtins.cc (c_readstr): Likewise.  Build a local array of
	bytes and use native_decode_rtx to get the rtx image.
	(builtin_memcpy_read_str): Simplify accordingly.
	(builtin_strncpy_read_str): Likewise.
	(builtin_memset_read_str): Likewise.
	(builtin_memset_gen_str): Likewise.
	* expr.cc (string_cst_read_str): Likewise.
This commit is contained in:
Richard Sandiford 2023-09-29 09:24:43 +01:00
parent a561369743
commit bcc97edf8c
3 changed files with 14 additions and 41 deletions
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46
gcc/builtins.cc
View file

@ -743,39 +743,22 @@ c_strlen (tree arg, int only_value, c_strlen_data *data, unsigned eltsize)
as needed. */
rtx
c_readstr (const char *str, scalar_int_mode mode,
c_readstr (const char *str, fixed_size_mode mode,
bool null_terminated_p/*=true*/)
{
HOST_WIDE_INT ch;
unsigned int i, j;
HOST_WIDE_INT tmp[MAX_BITSIZE_MODE_ANY_INT / HOST_BITS_PER_WIDE_INT];
auto_vec<target_unit, MAX_BITSIZE_MODE_ANY_INT / BITS_PER_UNIT> bytes;
gcc_assert (GET_MODE_CLASS (mode) == MODE_INT);
unsigned int len = (GET_MODE_PRECISION (mode) + HOST_BITS_PER_WIDE_INT - 1)
/ HOST_BITS_PER_WIDE_INT;
bytes.reserve (GET_MODE_SIZE (mode));
gcc_assert (len <= MAX_BITSIZE_MODE_ANY_INT / HOST_BITS_PER_WIDE_INT);
for (i = 0; i < len; i++)
tmp[i] = 0;
ch = 1;
for (i = 0; i < GET_MODE_SIZE (mode); i++)
target_unit ch = 1;
for (unsigned int i = 0; i < GET_MODE_SIZE (mode); ++i)
{
j = i;
if (WORDS_BIG_ENDIAN)
j = GET_MODE_SIZE (mode) - i - 1;
if (BYTES_BIG_ENDIAN != WORDS_BIG_ENDIAN
&& GET_MODE_SIZE (mode) >= UNITS_PER_WORD)
j = j + UNITS_PER_WORD - 2 * (j % UNITS_PER_WORD) - 1;
j *= BITS_PER_UNIT;
if (ch || !null_terminated_p)
ch = (unsigned char) str[i];
tmp[j / HOST_BITS_PER_WIDE_INT] |= ch << (j % HOST_BITS_PER_WIDE_INT);
bytes.quick_push (ch);
}
wide_int c = wide_int::from_array (tmp, len, GET_MODE_PRECISION (mode));
return immed_wide_int_const (c, mode);
return native_decode_rtx (mode, bytes, 0);
}
/* Cast a target constant CST to target CHAR and if that value fits into
@ -3530,10 +3513,7 @@ builtin_memcpy_read_str (void *data, void *, HOST_WIDE_INT offset,
string but the caller guarantees it's large enough for MODE. */
const char *rep = (const char *) data;
/* The by-pieces infrastructure does not try to pick a vector mode
for memcpy expansion. */
return c_readstr (rep + offset, as_a <scalar_int_mode> (mode),
/*nul_terminated=*/false);
return c_readstr (rep + offset, mode, /*nul_terminated=*/false);
}
/* LEN specify length of the block of memcpy/memset operation.
@ -3994,9 +3974,7 @@ builtin_strncpy_read_str (void *data, void *, HOST_WIDE_INT offset,
if ((unsigned HOST_WIDE_INT) offset > strlen (str))
return const0_rtx;
/* The by-pieces infrastructure does not try to pick a vector mode
for strncpy expansion. */
return c_readstr (str + offset, as_a <scalar_int_mode> (mode));
return c_readstr (str + offset, mode);
}
/* Helper to check the sizes of sequences and the destination of calls
@ -4227,8 +4205,7 @@ builtin_memset_read_str (void *data, void *prev,
memset (p, *c, size);
/* Vector modes should be handled above. */
return c_readstr (p, as_a <scalar_int_mode> (mode));
return c_readstr (p, mode);
}
/* Callback routine for store_by_pieces. Return the RTL of a register
@ -4275,8 +4252,7 @@ builtin_memset_gen_str (void *data, void *prev,
p = XALLOCAVEC (char, size);
memset (p, 1, size);
/* Vector modes should be handled above. */
coeff = c_readstr (p, as_a <scalar_int_mode> (mode));
coeff = c_readstr (p, mode);
target = convert_to_mode (mode, (rtx) data, 1);
target = expand_mult (mode, target, coeff, NULL_RTX, 1);

2
gcc/builtins.h
View file

@ -105,7 +105,7 @@ struct c_strlen_data
};
extern tree c_strlen (tree, int, c_strlen_data * = NULL, unsigned = 1);
extern rtx c_readstr (const char *, scalar_int_mode, bool = true);
extern rtx c_readstr (const char *, fixed_size_mode, bool = true);
extern void expand_builtin_setjmp_setup (rtx, rtx);
extern void expand_builtin_setjmp_receiver (rtx);
extern void expand_builtin_update_setjmp_buf (rtx);

7
gcc/expr.cc
View file

@ -6083,13 +6083,10 @@ string_cst_read_str (void *data, void *, HOST_WIDE_INT offset,
size_t l = TREE_STRING_LENGTH (str) - offset;
memcpy (p, TREE_STRING_POINTER (str) + offset, l);
memset (p + l, '\0', GET_MODE_SIZE (mode) - l);
return c_readstr (p, as_a <scalar_int_mode> (mode), false);
return c_readstr (p, mode, false);
}
/* The by-pieces infrastructure does not try to pick a vector mode
for storing STRING_CST. */
return c_readstr (TREE_STRING_POINTER (str) + offset,
as_a <scalar_int_mode> (mode), false);
return c_readstr (TREE_STRING_POINTER (str) + offset, mode, false);
}
/* Generate code for computing expression EXP,