tm.texi (CLZ_DEFINED_VALUE_AT_ZERO, [...]): Document change in interpretation of value from boolean to tri-state integer.
2007-08-09 Sandra Loosemore <sandra@codesourcery.com> Nigel Stephens <nigel@mips.com> gcc/ * doc/tm.texi (CLZ_DEFINED_VALUE_AT_ZERO, CTZ_DEFINED_VALUE_AT_ZERO): Document change in interpretation of value from boolean to tri-state integer. * optabs.c (expand_ffs, expand_ctz): New functions to compute ffs and ctz using clz. (expand_unop): Call them. * config/rs6000/rs6000.h (CLZ_DEFINED_VALUE_AT_ZERO): Fix its result value. (CTZ_DEFINED_VALUE_AT_ZERO): Likewise. * config/mips/mips.h (CLZ_DEFINED_VALUE_AT_ZERO): Likewise, to enable the new ffs expansion on this target. Co-Authored-By: Nigel Stephens <nigel@mips.com> From-SVN: r127318
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@ -1,3 +1,18 @@
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2007-08-09 Sandra Loosemore <sandra@codesourcery.com>
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Nigel Stephens <nigel@mips.com>
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* doc/tm.texi (CLZ_DEFINED_VALUE_AT_ZERO, CTZ_DEFINED_VALUE_AT_ZERO):
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Document change in interpretation of value from boolean to
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tri-state integer.
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* optabs.c (expand_ffs, expand_ctz): New functions to compute
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ffs and ctz using clz.
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(expand_unop): Call them.
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* config/rs6000/rs6000.h (CLZ_DEFINED_VALUE_AT_ZERO): Fix its
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result value.
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(CTZ_DEFINED_VALUE_AT_ZERO): Likewise.
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* config/mips/mips.h (CLZ_DEFINED_VALUE_AT_ZERO): Likewise, to
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enable the new ffs expansion on this target.
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2007-08-09 Jan Hubicka <jh@suse.cz>
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* optabs.c (expand_widen_pattern_expr): Use optabs accestors.
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@ -1295,7 +1295,7 @@ extern enum mips_code_readable_setting mips_code_readable;
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/* The [d]clz instructions have the natural values at 0. */
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#define CLZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE) \
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((VALUE) = GET_MODE_BITSIZE (MODE), true)
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((VALUE) = GET_MODE_BITSIZE (MODE), 2)
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/* Standard register usage. */
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@ -1856,10 +1856,10 @@ do { \
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/* The cntlzw and cntlzd instructions return 32 and 64 for input of zero. */
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#define CLZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE) \
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((VALUE) = ((MODE) == SImode ? 32 : 64))
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((VALUE) = ((MODE) == SImode ? 32 : 64), 1)
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/* The CTZ patterns return -1 for input of zero. */
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#define CTZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE) ((VALUE) = -1)
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#define CTZ_DEFINED_VALUE_AT_ZERO(MODE, VALUE) ((VALUE) = -1, 1)
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/* Specify the machine mode that pointers have.
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After generation of rtl, the compiler makes no further distinction
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@ -9638,14 +9638,23 @@ given mode.
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@defmac CLZ_DEFINED_VALUE_AT_ZERO (@var{mode}, @var{value})
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@defmacx CTZ_DEFINED_VALUE_AT_ZERO (@var{mode}, @var{value})
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A C expression that evaluates to true if the architecture defines a value
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for @code{clz} or @code{ctz} with a zero operand. If so, @var{value}
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should be set to this value. If this macro is not defined, the value of
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@code{clz} or @code{ctz} is assumed to be undefined.
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A C expression that indicates whether the architecture defines a value
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for @code{clz} or @code{ctz} with a zero operand.
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A result of @code{0} indicates the value is undefined.
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If the value is defined for only the RTL expression, the macro should
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evaluate to @code{1}; if the value applies also to the corresponding optab
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entry (which is normally the case if it expands directly into
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the corresponding RTL), then the macro should evaluate to @code{2}.
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In the cases where the value is defined, @var{value} should be set to
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this value.
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If this macro is not defined, the value of @code{clz} or
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@code{ctz} at zero is assumed to be undefined.
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This macro must be defined if the target's expansion for @code{ffs}
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relies on a particular value to get correct results. Otherwise it
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is not necessary, though it may be used to optimize some corner cases.
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is not necessary, though it may be used to optimize some corner cases, and
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to provide a default expansion for the @code{ffs} optab.
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Note that regardless of this macro the ``definedness'' of @code{clz}
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and @code{ctz} at zero do @emph{not} extend to the builtin functions
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80
gcc/optabs.c
80
gcc/optabs.c
@ -122,6 +122,8 @@ static void prepare_float_lib_cmp (rtx *, rtx *, enum rtx_code *,
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enum machine_mode *, int *);
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static rtx widen_clz (enum machine_mode, rtx, rtx);
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static rtx expand_parity (enum machine_mode, rtx, rtx);
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static rtx expand_ffs (enum machine_mode, rtx, rtx);
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static rtx expand_ctz (enum machine_mode, rtx, rtx);
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static enum rtx_code get_rtx_code (enum tree_code, bool);
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static rtx vector_compare_rtx (tree, bool, enum insn_code);
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@ -2561,6 +2563,68 @@ expand_parity (enum machine_mode mode, rtx op0, rtx target)
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return 0;
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}
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/* Try calculating ffs(x) using clz(x). Since the ffs builtin promises
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to return zero for a zero value and clz may have an undefined value
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in that case, only do this if we know clz returns the right thing so
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that we don't have to generate a test and branch. */
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static rtx
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expand_ffs (enum machine_mode mode, rtx op0, rtx target)
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{
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HOST_WIDE_INT val;
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if (clz_optab->handlers[(int) mode].insn_code != CODE_FOR_nothing
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&& CLZ_DEFINED_VALUE_AT_ZERO (mode, val) == 2
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&& val == GET_MODE_BITSIZE (mode))
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{
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rtx last = get_last_insn ();
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rtx temp;
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temp = expand_unop (mode, neg_optab, op0, NULL_RTX, true);
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if (temp)
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temp = expand_binop (mode, and_optab, op0, temp, NULL_RTX,
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true, OPTAB_DIRECT);
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if (temp)
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temp = expand_unop (mode, clz_optab, temp, NULL_RTX, true);
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if (temp)
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temp = expand_binop (mode, sub_optab,
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GEN_INT (GET_MODE_BITSIZE (mode)),
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temp,
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target, true, OPTAB_DIRECT);
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if (temp == 0)
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delete_insns_since (last);
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return temp;
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}
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return 0;
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}
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/* We can compute ctz(x) using clz(x) with a similar recipe. Here the ctz
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builtin has an undefined result on zero, just like clz, so we don't have
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to do that check. */
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static rtx
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expand_ctz (enum machine_mode mode, rtx op0, rtx target)
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{
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if (clz_optab->handlers[(int) mode].insn_code != CODE_FOR_nothing)
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{
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rtx last = get_last_insn ();
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rtx temp;
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temp = expand_unop (mode, neg_optab, op0, NULL_RTX, true);
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if (temp)
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temp = expand_binop (mode, and_optab, op0, temp, NULL_RTX,
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true, OPTAB_DIRECT);
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if (temp)
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temp = expand_unop (mode, clz_optab, temp, NULL_RTX, true);
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if (temp)
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temp = expand_binop (mode, xor_optab, temp,
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GEN_INT (GET_MODE_BITSIZE (mode) - 1),
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target,
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true, OPTAB_DIRECT);
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if (temp == 0)
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delete_insns_since (last);
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return temp;
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}
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return 0;
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}
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/* Extract the OMODE lowpart from VAL, which has IMODE. Under certain
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conditions, VAL may already be a SUBREG against which we cannot generate
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a further SUBREG. In this case, we expect forcing the value into a
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@ -2886,6 +2950,22 @@ expand_unop (enum machine_mode mode, optab unoptab, rtx op0, rtx target,
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return temp;
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}
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/* Try implementing ffs (x) in terms of clz (x). */
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if (unoptab == ffs_optab)
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{
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temp = expand_ffs (mode, op0, target);
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if (temp)
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return temp;
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}
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/* Try implementing ctz (x) in terms of clz (x). */
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if (unoptab == ctz_optab)
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{
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temp = expand_ctz (mode, op0, target);
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if (temp)
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return temp;
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}
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try_libcall:
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/* Now try a library call in this mode. */
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if (optab_handler (unoptab, mode)->libfunc)
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