From: Pan Li <[email protected]>
This patch would like to add the middle-end presentation for the
saturation truncation. Aka set the result of truncated value to
the max value when overflow. It will take the pattern similar
as below.
Form 1:
#define DEF_SAT_U_TRUC_FMT_1(WT, NT) \
NT __attribute__((noinline)) \
sat_u_truc_##T##_fmt_1 (WT x) \
{ \
bool overflow = x > (WT)(NT)(-1); \
return ((NT)x) | (NT)-overflow; \
}
For example, truncated uint16_t to uint8_t, we have
* SAT_TRUNC (254) => 254
* SAT_TRUNC (255) => 255
* SAT_TRUNC (256) => 255
* SAT_TRUNC (65536) => 255
Given below SAT_TRUNC from uint64_t to uint32_t.
DEF_SAT_U_TRUC_FMT_1 (uint64_t, uint32_t)
Before this patch:
__attribute__((noinline))
uint32_t sat_u_truc_T_fmt_1 (uint64_t x)
{
_Bool overflow;
unsigned int _1;
unsigned int _2;
unsigned int _3;
uint32_t _6;
;; basic block 2, loop depth 0
;; pred: ENTRY
overflow_5 = x_4(D) > 4294967295;
_1 = (unsigned int) x_4(D);
_2 = (unsigned int) overflow_5;
_3 = -_2;
_6 = _1 | _3;
return _6;
;; succ: EXIT
}
After this patch:
__attribute__((noinline))
uint32_t sat_u_truc_T_fmt_1 (uint64_t x)
{
uint32_t _6;
;; basic block 2, loop depth 0
;; pred: ENTRY
_6 = .SAT_TRUNC (x_4(D)); [tail call]
return _6;
;; succ: EXIT
}
The below tests are passed for this patch:
*. The rv64gcv fully regression tests.
*. The rv64gcv build with glibc.
*. The x86 bootstrap tests.
*. The x86 fully regression tests.
gcc/ChangeLog:
* internal-fn.def (SAT_TRUNC): Add new signed IFN sat_trunc as
unary_convert.
* match.pd: Add new matching pattern for unsigned int sat_trunc.
* optabs.def (OPTAB_CL): Add unsigned and signed optab.
* tree-ssa-math-opts.cc (gimple_unsigend_integer_sat_trunc): Add
new decl for the matching pattern generated func.
(match_unsigned_saturation_trunc): Add new func impl to match
the .SAT_TRUNC.
(math_opts_dom_walker::after_dom_children): Add .SAT_TRUNC match
function under BIT_IOR_EXPR case.
* tree.cc (integer_half_truncated_all_ones_p): Add new func impl
to filter the truncated threshold.
* tree.h (integer_half_truncated_all_ones_p): Add new func decl.
Signed-off-by: Pan Li <[email protected]>
---
gcc/internal-fn.def | 2 ++
gcc/match.pd | 12 +++++++++++-
gcc/optabs.def | 3 +++
gcc/tree-ssa-math-opts.cc | 32 ++++++++++++++++++++++++++++++++
gcc/tree.cc | 22 ++++++++++++++++++++++
gcc/tree.h | 6 ++++++
6 files changed, 76 insertions(+), 1 deletion(-)
diff --git a/gcc/internal-fn.def b/gcc/internal-fn.def
index a8c83437ada..915d329c05a 100644
--- a/gcc/internal-fn.def
+++ b/gcc/internal-fn.def
@@ -278,6 +278,8 @@ DEF_INTERNAL_SIGNED_OPTAB_FN (MULHRS, ECF_CONST |
ECF_NOTHROW, first,
DEF_INTERNAL_SIGNED_OPTAB_FN (SAT_ADD, ECF_CONST, first, ssadd, usadd, binary)
DEF_INTERNAL_SIGNED_OPTAB_FN (SAT_SUB, ECF_CONST, first, sssub, ussub, binary)
+DEF_INTERNAL_SIGNED_OPTAB_FN (SAT_TRUNC, ECF_CONST, first, sstrunc, ustrunc,
unary_convert)
+
DEF_INTERNAL_COND_FN (ADD, ECF_CONST, add, binary)
DEF_INTERNAL_COND_FN (SUB, ECF_CONST, sub, binary)
DEF_INTERNAL_COND_FN (MUL, ECF_CONST, smul, binary)
diff --git a/gcc/match.pd b/gcc/match.pd
index 3d0689c9312..d4062434cc7 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -39,7 +39,8 @@ along with GCC; see the file COPYING3. If not see
HONOR_NANS
uniform_vector_p
expand_vec_cmp_expr_p
- bitmask_inv_cst_vector_p)
+ bitmask_inv_cst_vector_p
+ integer_half_truncated_all_ones_p)
/* Operator lists. */
(define_operator_list tcc_comparison
@@ -3210,6 +3211,15 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
&& types_match (type, @0, @1))))
+/* Unsigned saturation truncate, case 1 (), sizeof (WT) > sizeof (NT).
+ SAT_U_TRUNC = (NT)x | (NT)(-(X > (WT)(NT)(-1))). */
+(match (unsigend_integer_sat_trunc @0)
+ (bit_ior:c (negate (convert (gt @0 integer_half_truncated_all_ones_p)))
+ (convert @0))
+ (if (INTEGRAL_TYPE_P (type) && TYPE_UNSIGNED (type)
+ && TYPE_UNSIGNED (TREE_TYPE (@0))
+ && tree_int_cst_lt (TYPE_SIZE (type), TYPE_SIZE (TREE_TYPE (@0))))))
+
/* x > y && x != XXX_MIN --> x > y
x > y && x == XXX_MIN --> false . */
(for eqne (eq ne)
diff --git a/gcc/optabs.def b/gcc/optabs.def
index bc2611abdc2..4eaffe96c19 100644
--- a/gcc/optabs.def
+++ b/gcc/optabs.def
@@ -63,6 +63,9 @@ OPTAB_CX(fractuns_optab, "fractuns$Q$b$I$a2")
OPTAB_CL(satfract_optab, "satfract$b$Q$a2", SAT_FRACT, "satfract",
gen_satfract_conv_libfunc)
OPTAB_CL(satfractuns_optab, "satfractuns$I$b$Q$a2", UNSIGNED_SAT_FRACT,
"satfractuns", gen_satfractuns_conv_libfunc)
+OPTAB_CL(ustrunc_optab, "ustrunc$b$a2", US_TRUNCATE, "ustrunc",
gen_satfract_conv_libfunc)
+OPTAB_CL(sstrunc_optab, "sstrunc$b$a2", SS_TRUNCATE, "sstrunc",
gen_satfract_conv_libfunc)
+
OPTAB_CD(sfixtrunc_optab, "fix_trunc$F$b$I$a2")
OPTAB_CD(ufixtrunc_optab, "fixuns_trunc$F$b$I$a2")
diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc
index 57085488722..64bc70c29b3 100644
--- a/gcc/tree-ssa-math-opts.cc
+++ b/gcc/tree-ssa-math-opts.cc
@@ -4088,6 +4088,7 @@ arith_overflow_check_p (gimple *stmt, gimple *cast_stmt,
gimple *&use_stmt,
extern bool gimple_unsigned_integer_sat_add (tree, tree*, tree (*)(tree));
extern bool gimple_unsigned_integer_sat_sub (tree, tree*, tree (*)(tree));
+extern bool gimple_unsigend_integer_sat_trunc (tree, tree*, tree (*)(tree));
static void
build_saturation_binary_arith_call (gimple_stmt_iterator *gsi, internal_fn fn,
@@ -4216,6 +4217,36 @@ match_unsigned_saturation_sub (gimple_stmt_iterator
*gsi, gphi *phi)
ops[0], ops[1]);
}
+/*
+ * Try to match saturation unsigned sub.
+ * uint16_t x_4(D);
+ * uint8_t _6;
+ * overflow_5 = x_4(D) > 255;
+ * _1 = (unsigned char) x_4(D);
+ * _2 = (unsigned char) overflow_5;
+ * _3 = -_2;
+ * _6 = _1 | _3;
+ * =>
+ * _6 = .SAT_TRUNC (x_4(D));
+ * */
+static void
+match_unsigned_saturation_trunc (gimple_stmt_iterator *gsi, gassign *stmt)
+{
+ tree ops[1];
+ tree lhs = gimple_assign_lhs (stmt);
+ tree type = TREE_TYPE (lhs);
+
+ if (gimple_unsigend_integer_sat_trunc (lhs, ops, NULL)
+ && direct_internal_fn_supported_p (IFN_SAT_TRUNC,
+ tree_pair (type, TREE_TYPE (ops[0])),
+ OPTIMIZE_FOR_BOTH))
+ {
+ gcall *call = gimple_build_call_internal (IFN_SAT_TRUNC, 1, ops[0]);
+ gimple_call_set_lhs (call, lhs);
+ gsi_replace (gsi, call, /* update_eh_info */ true);
+ }
+}
+
/* Recognize for unsigned x
x = y - z;
if (x > y)
@@ -6188,6 +6219,7 @@ math_opts_dom_walker::after_dom_children (basic_block bb)
case BIT_IOR_EXPR:
match_unsigned_saturation_add (&gsi, as_a<gassign *> (stmt));
+ match_unsigned_saturation_trunc (&gsi, as_a<gassign *> (stmt));
/* fall-through */
case BIT_XOR_EXPR:
match_uaddc_usubc (&gsi, stmt, code);
diff --git a/gcc/tree.cc b/gcc/tree.cc
index 2d2d5b6db6e..4572e6fc42b 100644
--- a/gcc/tree.cc
+++ b/gcc/tree.cc
@@ -2944,6 +2944,28 @@ integer_all_onesp (const_tree expr)
== wi::to_wide (expr));
}
+/* Return true if EXPR is an integer constant of all ones with half
+ truncated in precision. Or return false. For example:
+ uint16_t a = 255; // true.
+ uint16_t b = 0; // false.
+ uint16_t c = 65545; // false. */
+bool
+integer_half_truncated_all_ones_p (const_tree expr)
+{
+ if (TREE_CODE (expr) != INTEGER_CST)
+ return false;
+
+ unsigned precision = TYPE_PRECISION (TREE_TYPE (expr));
+
+ gcc_assert (precision <= 64);
+
+ unsigned trunc_prec = precision / 2;
+ wide_int trunc_max = wi::uhwi ((uint64_t)-1 >> (64 - trunc_prec), precision);
+ wide_int expr_int = wi::to_wide (expr, precision);
+
+ return trunc_max == expr_int;
+}
+
/* Return true if EXPR is the integer constant minus one, or a location
wrapper for such a constant. */
diff --git a/gcc/tree.h b/gcc/tree.h
index 28e8e71b036..0237826dd23 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -5205,6 +5205,12 @@ extern bool integer_each_onep (const_tree);
extern bool integer_all_onesp (const_tree);
+/* integer_half_truncated_all_ones_p (tree x) will return true if x is
+ the integer constant that the half truncated bits are all 1.
+ For example, uint16_t type with 255 constant integer will be true. */
+
+extern bool integer_half_truncated_all_ones_p (const_tree expr);
+
/* integer_minus_onep (tree x) is nonzero if X is an integer constant of
value -1. */
--
2.34.1
