[PATCH] Constant fold VIEW_CONVERT_EXPR (take 2)
Roger Sayle
roger@eyesopen.com
Thu Apr 13 18:13:00 GMT 2006
On Wed, 12 Apr 2006, Richard Henderson wrote:
> On Wed, Apr 12, 2006 at 08:01:56AM -0600, Roger Sayle wrote:
> > + native_encode_expr (tree expr, unsigned char *ptr, int len)
>
> I think this should be split into native_encode_{int,real,...}
> with native_encode_expr calling them. Use a switch. At present
> the function is on the "too big" side.
>
> > + native_interpret_expr (tree type, unsigned char *ptr, int len)
> Likewise.
>
> > if (TREE_CODE (op0) == VIEW_CONVERT_EXPR)
> > ! return fold_build1 (VIEW_CONVERT_EXPR, type, TREE_OPERAND (op0, 0));
> > ! if (TREE_CODE (op0) == INTEGER_CST
> > ! || TREE_CODE (op0) == REAL_CST
> > ! || TREE_CODE (op0) == COMPLEX_CST
> > ! || TREE_CODE (op0) == VECTOR_CST)
> > ! return fold_view_convert_expr (type, op0);
>
> Why are you encoding this information here? You should be able
> to just call this function and get your null.
No problem. The following revision has been retested on i686-pc-linux-gnu
with a full "make bootstrap", all default languages including Ada, and
regression tested with a top-level "make -k check" with no new failures.
Ok for mainline?
2006-04-13 Roger Sayle <roger@eyesopen.com>
* fold-const.c (native_encode_expr): New function to encode
the target representation of an INTEGER_CST, REAL_CST, COMPLEX_CST
or VECTOR_CST into a specified buffer.
(native_encode_int): New function.
(native_encode_real): New function.
(native_encode_complex): New function.
(native_encode_vector): New function.
(native_interpret_expr): Inverse of native_encode_expr to convert
a target representation into an INTEGER_CST, REAL_CST etc...
(native_interpret_int): New function.
(native_interpret_real): New function.
(native_interpret_complex): New function.
(native_interpret_vector): New function.
(fold_view_convert_expr): New function to constant fold/evaluate
a VIEW_CONVERT_EXPR of a suitable constant expression.
(fold_unary) <VIEW_CONVERT_EXPR>: Call fold_view_convert_expr.
Change call of build1 to fold_build1 when constructing a
VIEW_CONVERT_EXPR.
* gcc.target/i386/20050113-1.c: Tweak testcase to reflect that casts
of integers to a vector types are now constant expressions in C.
* gcc.dg/vect/vect-fold-1.c: New test case.
Index: fold-const.c
===================================================================
*** fold-const.c (revision 112888)
--- fold-const.c (working copy)
*************** static bool reorder_operands_p (tree, tr
*** 134,139 ****
--- 134,142 ----
static tree fold_negate_const (tree, tree);
static tree fold_not_const (tree, tree);
static tree fold_relational_const (enum tree_code, tree, tree, tree);
+ static int native_encode_expr (tree, unsigned char *, int);
+ static tree native_interpret_expr (tree, unsigned char *, int);
+
/* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
*************** fold_plusminus_mult_expr (enum tree_code
*** 6756,6761 ****
--- 6759,7156 ----
return NULL_TREE;
}
+ /* Subroutine of native_encode_expr. Encode the INTEGER_CST
+ specified by EXPR into the buffer PTR of length LEN bytes.
+ Return the number of bytes placed in the buffer, or zero
+ upon failure. */
+
+ static int
+ native_encode_int (tree expr, unsigned char *ptr, int len)
+ {
+ tree type = TREE_TYPE (expr);
+ int total_bytes = GET_MODE_SIZE (TYPE_MODE (type));
+ int byte, offset, word, words;
+ unsigned char value;
+
+ if (total_bytes > len)
+ return 0;
+ words = total_bytes / UNITS_PER_WORD;
+
+ for (byte = 0; byte < total_bytes; byte++)
+ {
+ int bitpos = byte * BITS_PER_UNIT;
+ if (bitpos < HOST_BITS_PER_WIDE_INT)
+ value = (unsigned char) (TREE_INT_CST_LOW (expr) >> bitpos);
+ else
+ value = (unsigned char) (TREE_INT_CST_HIGH (expr)
+ >> (bitpos - HOST_BITS_PER_WIDE_INT));
+
+ if (total_bytes > UNITS_PER_WORD)
+ {
+ word = byte / UNITS_PER_WORD;
+ if (WORDS_BIG_ENDIAN)
+ word = (words - 1) - word;
+ offset = word * UNITS_PER_WORD;
+ if (BYTES_BIG_ENDIAN)
+ offset += (UNITS_PER_WORD - 1) - (byte % UNITS_PER_WORD);
+ else
+ offset += byte % UNITS_PER_WORD;
+ }
+ else
+ offset = BYTES_BIG_ENDIAN ? (total_bytes - 1) - byte : byte;
+ ptr[offset] = value;
+ }
+ return total_bytes;
+ }
+
+
+ /* Subroutine of native_encode_expr. Encode the REAL_CST
+ specified by EXPR into the buffer PTR of length LEN bytes.
+ Return the number of bytes placed in the buffer, or zero
+ upon failure. */
+
+ static int
+ native_encode_real (tree expr, unsigned char *ptr, int len)
+ {
+ tree type = TREE_TYPE (expr);
+ int total_bytes = GET_MODE_SIZE (TYPE_MODE (type));
+ int byte, offset, word, words;
+ unsigned char value;
+
+ /* There are always 32 bits in each long, no matter the size of
+ the hosts long. We handle floating point representations with
+ up to 192 bits. */
+ long tmp[6];
+
+ if (total_bytes > len)
+ return 0;
+ words = total_bytes / UNITS_PER_WORD;
+
+ real_to_target (tmp, TREE_REAL_CST_PTR (expr), TYPE_MODE (type));
+
+ for (byte = 0; byte < total_bytes; byte++)
+ {
+ int bitpos = byte * BITS_PER_UNIT;
+ value = (unsigned char) (tmp[bitpos / 32] >> (bitpos & 31));
+
+ if (total_bytes > UNITS_PER_WORD)
+ {
+ word = byte / UNITS_PER_WORD;
+ if (FLOAT_WORDS_BIG_ENDIAN)
+ word = (words - 1) - word;
+ offset = word * UNITS_PER_WORD;
+ if (BYTES_BIG_ENDIAN)
+ offset += (UNITS_PER_WORD - 1) - (byte % UNITS_PER_WORD);
+ else
+ offset += byte % UNITS_PER_WORD;
+ }
+ else
+ offset = BYTES_BIG_ENDIAN ? (total_bytes - 1) - byte : byte;
+ ptr[offset] = value;
+ }
+ return total_bytes;
+ }
+
+ /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
+ specified by EXPR into the buffer PTR of length LEN bytes.
+ Return the number of bytes placed in the buffer, or zero
+ upon failure. */
+
+ static int
+ native_encode_complex (tree expr, unsigned char *ptr, int len)
+ {
+ int rsize, isize;
+ tree part;
+
+ part = TREE_REALPART (expr);
+ rsize = native_encode_expr (part, ptr, len);
+ if (rsize == 0)
+ return 0;
+ part = TREE_IMAGPART (expr);
+ isize = native_encode_expr (part, ptr+rsize, len-rsize);
+ if (isize != rsize)
+ return 0;
+ return rsize + isize;
+ }
+
+
+ /* Subroutine of native_encode_expr. Encode the VECTOR_CST
+ specified by EXPR into the buffer PTR of length LEN bytes.
+ Return the number of bytes placed in the buffer, or zero
+ upon failure. */
+
+ static int
+ native_encode_vector (tree expr, unsigned char *ptr, int len)
+ {
+ tree type = TREE_TYPE (expr);
+ int i, size, offste, count;
+ tree elem, elements;
+
+ size = 0;
+ offset = 0;
+ elements = TREE_VECTOR_CST_ELTS (expr);
+ count = TYPE_VECTOR_SUBPARTS (TREE_TYPE (expr));
+ for (i = 0; i < count; i++)
+ {
+ if (elements)
+ {
+ elem = TREE_VALUE (elements);
+ elements = TREE_CHAIN (elements);
+ }
+ else
+ elem = NULL_TREE;
+
+ if (elem)
+ {
+ size = native_encode_expr (elem, ptr+offset, len-offset);
+ if (size == 0)
+ return 0;
+ }
+ else if (size != 0)
+ {
+ if (offset + size > len)
+ return 0;
+ memset (ptr+offset, 0, size);
+ }
+ else
+ return 0;
+ offset += size;
+ }
+ return offset;
+ }
+
+
+ /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
+ REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
+ buffer PTR of length LEN bytes. Return the number of bytes
+ placed in the buffer, or zero upon failure. */
+
+ static int
+ native_encode_expr (tree expr, unsigned char *ptr, int len)
+ {
+ switch (TREE_CODE (expr))
+ {
+ case INTEGER_CST:
+ return native_encode_int (expr, ptr, len);
+
+ case REAL_CST:
+ return native_encode_real (expr, ptr, len);
+
+ case COMPLEX_CST:
+ return native_encode_complex (expr, ptr, len);
+
+ case VECTOR_CST:
+ return native_encode_vector (expr, ptr, len);
+
+ default:
+ return 0;
+ }
+ }
+
+
+ /* Subroutine of native_interpret_expr. Interpret the contents of
+ the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
+ If the buffer cannot be interpreted, return NULL_TREE. */
+
+ static tree
+ native_interpret_int (tree type, unsigned char *ptr, int len)
+ {
+ int total_bytes = GET_MODE_SIZE (TYPE_MODE (type));
+ int byte, offset, word, words;
+ unsigned char value;
+ unsigned int HOST_WIDE_INT lo = 0;
+ HOST_WIDE_INT hi = 0;
+
+ if (total_bytes > len)
+ return NULL_TREE;
+ if (total_bytes * BITS_PER_UNIT > 2 * HOST_BITS_PER_WIDE_INT)
+ return NULL_TREE;
+ words = total_bytes / UNITS_PER_WORD;
+
+ for (byte = 0; byte < total_bytes; byte++)
+ {
+ int bitpos = byte * BITS_PER_UNIT;
+ if (total_bytes > UNITS_PER_WORD)
+ {
+ word = byte / UNITS_PER_WORD;
+ if (WORDS_BIG_ENDIAN)
+ word = (words - 1) - word;
+ offset = word * UNITS_PER_WORD;
+ if (BYTES_BIG_ENDIAN)
+ offset += (UNITS_PER_WORD - 1) - (byte % UNITS_PER_WORD);
+ else
+ offset += byte % UNITS_PER_WORD;
+ }
+ else
+ offset = BYTES_BIG_ENDIAN ? (total_bytes - 1) - byte : byte;
+ value = ptr[offset];
+
+ if (bitpos < HOST_BITS_PER_WIDE_INT)
+ lo |= (unsigned HOST_WIDE_INT) value << bitpos;
+ else
+ hi |= (unsigned HOST_WIDE_INT) value
+ << (bitpos - HOST_BITS_PER_WIDE_INT);
+ }
+
+ return force_fit_type (build_int_cst_wide (type, lo, hi),
+ 0, false, false);
+ }
+
+
+ /* Subroutine of native_interpret_expr. Interpret the contents of
+ the buffer PTR of length LEN as a REAL_CST of type TYPE.
+ If the buffer cannot be interpreted, return NULL_TREE. */
+
+ static tree
+ native_interpret_real (tree type, unsigned char *ptr, int len)
+ {
+ int total_bytes = GET_MODE_SIZE (TYPE_MODE (type));
+ int byte, offset, word, words;
+ unsigned char value;
+ /* There are always 32 bits in each long, no matter the size of
+ the hosts long. We handle floating point representations with
+ up to 192 bits. */
+ REAL_VALUE_TYPE r;
+ long tmp[6];
+
+ total_bytes = GET_MODE_SIZE (TYPE_MODE (type));
+ if (total_bytes > len || total_bytes > 24)
+ return NULL_TREE;
+ words = total_bytes / UNITS_PER_WORD;
+
+ memset (tmp, 0, sizeof (tmp));
+ for (byte = 0; byte < total_bytes; byte++)
+ {
+ int bitpos = byte * BITS_PER_UNIT;
+ if (total_bytes > UNITS_PER_WORD)
+ {
+ word = byte / UNITS_PER_WORD;
+ if (FLOAT_WORDS_BIG_ENDIAN)
+ word = (words - 1) - word;
+ offset = word * UNITS_PER_WORD;
+ if (BYTES_BIG_ENDIAN)
+ offset += (UNITS_PER_WORD - 1) - (byte % UNITS_PER_WORD);
+ else
+ offset += byte % UNITS_PER_WORD;
+ }
+ else
+ offset = BYTES_BIG_ENDIAN ? (total_bytes - 1) - byte : byte;
+ value = ptr[offset];
+
+ tmp[bitpos / 32] |= (unsigned long)value << (bitpos & 31);
+ }
+
+ real_from_target (&r, tmp, mode);
+ return build_real (type, r);
+ }
+
+
+ /* Subroutine of native_interpret_expr. Interpret the contents of
+ the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
+ If the buffer cannot be interpreted, return NULL_TREE. */
+
+ static tree
+ native_interpret_complex (tree type, unsigned char *ptr, int len)
+ {
+ tree etype, rpart, ipart;
+ int size;
+
+ etype = TREE_TYPE (type);
+ size = GET_MODE_SIZE (TYPE_MODE (etype));
+ if (size * 2 > len)
+ return NULL_TREE;
+ rpart = native_interpret_expr (etype, ptr, size);
+ if (!rpart)
+ return NULL_TREE;
+ ipart = native_interpret_expr (etype, ptr+size, size);
+ if (!ipart)
+ return NULL_TREE;
+ return build_complex (type, rpart, ipart);
+ }
+
+
+ /* Subroutine of native_interpret_expr. Interpret the contents of
+ the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
+ If the buffer cannot be interpreted, return NULL_TREE. */
+
+ static tree
+ native_interpret_vector (tree type, unsigned char *ptr, int len)
+ {
+ tree etype, elem, elements;
+ int i, size, count;
+
+ etype = TREE_TYPE (type);
+ size = GET_MODE_SIZE (TYPE_MODE (etype));
+ count = TYPE_VECTOR_SUBPARTS (type);
+ if (size * count > len)
+ return NULL_TREE;
+
+ elements = NULL_TREE;
+ for (i = count - 1; i >= 0; i--)
+ {
+ elem = native_interpret_expr (etype, ptr+(i*size), size);
+ if (!elem)
+ return NULL_TREE;
+ elements = tree_cons (NULL_TREE, elem, elements);
+ }
+ return build_vector (type, elements);
+ }
+
+
+ /* Subroutine of fold_view_convert_expr. Interpet the contents of
+ the buffer PTR of length LEN as a constant of type TYPE. For
+ INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
+ we return a REAL_CST, etc... If the buffer cannot be interpreted,
+ return NULL_TREE. */
+
+ static tree
+ native_interpret_expr (tree type, unsigned char *ptr, int len)
+ {
+ switch (TREE_CODE (type))
+ {
+ case INTEGER_TYPE:
+ case ENUMERAL_TYPE:
+ case BOOLEAN_TYPE:
+ return native_interpret_int (type, ptr, len);
+
+ case REAL_TYPE:
+ return native_interpret_real (type, ptr, len);
+
+ case COMPLEX_TYPE:
+ return native_interpret_complex (type, ptr, len);
+
+ case VECTOR_TYPE:
+ return native_interpret_vector (type, ptr, len);
+
+ default:
+ return NULL_TREE;
+ }
+ }
+
+
+ /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
+ TYPE at compile-time. If we're unable to perform the conversion
+ return NULL_TREE. */
+
+ static tree
+ fold_view_convert_expr (tree type, tree expr)
+ {
+ /* We support up to 512-bit values (for V8DFmode). */
+ unsigned char buffer[64];
+ int len;
+
+ /* Check that the host and target are sane. */
+ if (CHAR_BIT != 8 || BITS_PER_UNIT != 8)
+ return NULL_TREE;
+
+ len = native_encode_expr (expr, buffer, sizeof (buffer));
+ if (len == 0)
+ return NULL_TREE;
+
+ return native_interpret_expr (type, buffer, len);
+ }
+
+
/* Fold a unary expression of code CODE and type TYPE with operand
OP0. Return the folded expression if folding is successful.
Otherwise, return NULL_TREE. */
*************** fold_unary (enum tree_code code, tree ty
*** 7095,7102 ****
case VIEW_CONVERT_EXPR:
if (TREE_CODE (op0) == VIEW_CONVERT_EXPR)
! return build1 (VIEW_CONVERT_EXPR, type, TREE_OPERAND (op0, 0));
! return NULL_TREE;
case NEGATE_EXPR:
if (negate_expr_p (arg0))
--- 7490,7497 ----
case VIEW_CONVERT_EXPR:
if (TREE_CODE (op0) == VIEW_CONVERT_EXPR)
! return fold_build1 (VIEW_CONVERT_EXPR, type, TREE_OPERAND (op0, 0));
! return fold_view_convert_expr (type, op0);
case NEGATE_EXPR:
if (negate_expr_p (arg0))
Roger
--
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