Hi Jakub,
Thank you for reviewing the patch.
I have incorporated your comments in the attached patch.
> -----Original Message-----
> From: Jakub Jelinek [mailto:ja...@redhat.com]
> Sent: Wednesday, July 29, 2015 1:24 AM
> To: Kumar, Venkataramanan
> Cc: Richard Beiner (richard.guent...@gmail.com); gcc-patches@gcc.gnu.org
> Subject: Re: [RFC] [Patch]: Try and vectorize with shift for mult expr with
> power 2 integer constant.
>
> Hi!
>
> > This is just an initial patch and tries to optimize integer type power
> > 2 constants. I wanted to get feedback on this . I bootstrapped and
> > reg tested on aarch64-none-linux-gnu .
>
> Thanks for working on it.
> ChangeLog entry for the patch is missing, probably also some testcases.
>
> > @@ -90,6 +94,7 @@ static vect_recog_func_ptr
> vect_vect_recog_func_ptrs[NUM_PATTERNS] = {
> > vect_recog_rotate_pattern,
> > vect_recog_vector_vector_shift_pattern,
> > vect_recog_divmod_pattern,
> > + vect_recog_multconst_pattern,
> > vect_recog_mixed_size_cond_pattern,
> > vect_recog_bool_pattern};
>
> Please watch formatting, the other lines are tab indented, so please use a
> tab rather than 8 spaces.
>
> > @@ -2147,6 +2152,87 @@ vect_recog_vector_vector_shift_pattern
> (vec<gimple> *stmts,
> > return pattern_stmt;
> > }
> >
>
> Function comment is missing here.
>
> > +static gimple
> > +vect_recog_multconst_pattern (vec<gimple> *stmts,
> > + tree *type_in, tree *type_out)
>
> About the function name, wonder if just vect_recog_mult_pattern wouldn't
> be enough.
>
> > + rhs_code = gimple_assign_rhs_code (last_stmt); switch (rhs_code)
> > + {
> > + case MULT_EXPR:
> > + break;
> > + default:
> > + return NULL;
> > + }
>
> This looks too weird, I'd just do
> if (gimple_assign_rhs_code (last_stmt) != MULT_EXPR)
> return NULL;
> (you handle just one pattern).
>
> > + /* If the target can handle vectorized multiplication natively,
> > + don't attempt to optimize this. */ optab = optab_for_tree_code
> > + (rhs_code, vectype, optab_default);
>
> Supposedly you can use MULT_EXPR directly here.
>
> > + /* If target cannot handle vector left shift then we cannot
> > + optimize and bail out. */
> > + optab = optab_for_tree_code (LSHIFT_EXPR, vectype, optab_vector);
> > + if (!optab
> > + || optab_handler (optab, TYPE_MODE (vectype)) ==
> CODE_FOR_nothing)
> > + return NULL;
> > +
> > + if (integer_pow2p (oprnd1))
> > + {
> > + /* Pattern detected. */
> > + if (dump_enabled_p ())
> > + dump_printf_loc (MSG_NOTE, vect_location,
> > + "vect_recog_multconst_pattern: detected:\n");
> > +
> > + tree shift;
> > + shift = build_int_cst (itype, tree_log2 (oprnd1));
> > + pattern_stmt = gimple_build_assign (vect_recog_temp_ssa_var
> (itype, NULL),
> > + LSHIFT_EXPR, oprnd0, shift);
> > + if (dump_enabled_p ())
> > + dump_gimple_stmt_loc (MSG_NOTE, vect_location, TDF_SLIM,
> pattern_stmt,
> > + 0);
> > + stmts->safe_push (last_stmt);
> > + *type_in = vectype;
> > + *type_out = vectype;
> > + return pattern_stmt;
> > + }
>
> Trailing whitespace.
> The integer_pow2p case (have you checked signed multiply by INT_MIN?) is
> only one of the cases you can actually handle, you can look at expand_mult
> for many other cases - e.g. multiplication by negated powers of 2, or call
> choose_mult_variant and handle whatever it returns.
I have added patterns that detect mults with power of 2 constants and convert
them to shifts in this patch.
I will do a follow up patch for other variants as done in "expand_mult" and
"choose_mult_variant".
INT_MIN case, I have not yet checked.
I thought of adding like this.
if (wi::eq_p (oprnd1, HOST_WIDE_INT_MIN))
return NULL;
But wanted to confirm with you since I don't understand this clearly. Is this
because Var * INT_MIN != Var << 31 ?
I tried this case for "int" or long int type arr
void test_vector_shifts()
{
for(i=0; i<=99;i++)
arr[i]=arr[i]*INT_MIN;
}
Int type- Looks like without my patch aarch64 vectorizes it using shifts.
ldr q0, [x0]
shl v0.4s, v0.4s, 31
str q0, [x0], 16
For long int type - without my patch it converts to shifts but vectorization
did not happen.
ldr x1, [x0]
neg x1, x1, lsl 31
str x1, [x0], 8
>
> Jakub
gcc/ChangeLog
2015-08-02 Venkataramanan Kumar <venkataramanan.ku...@amd.com>
* tree-vect-patterns.c (vect_recog_mult_pattern): New function for
vectorizing
multiplication patterns.
* tree-vectorizer.h: Adjust the number of patterns.
gcc/testsuite/ChangeLog
2015-08-02 Venkataramanan Kumar <venkataramanan.ku...@amd.com>
* gcc.dg/vect/vect-mult-patterns.c: New
Regards,
Venkat.
diff --git a/gcc/testsuite/gcc.dg/vect/vect-mult-patterns.c
b/gcc/testsuite/gcc.dg/vect/vect-mult-patterns.c
new file mode 100644
index 0000000..ad1760c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-mult-patterns.c
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_int } */
+/* { dg-require-effective-target vect_shift } */
+
+unsigned long int __attribute__ ((aligned (64)))arr[100];
+int i;
+
+void test_vector_shifts ()
+{
+ for (i=0; i<=99; i++)
+ arr[i] = arr[i] * 4;
+}
+
+void test_vectorshift_via_mul ()
+{
+ for (i=0; i<=99; i++)
+ arr[i] = arr[i] * (-4);
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" {target {
! { vect_int_mult } } } } } */
+/* { dg-final { scan-tree-dump-times "vect_recog_mult_pattern: detected" 2
"vect" {target { ! { vect_int_mult } } } } } */
diff --git a/gcc/tree-vect-patterns.c b/gcc/tree-vect-patterns.c
index f034635..5cbb49e 100644
--- a/gcc/tree-vect-patterns.c
+++ b/gcc/tree-vect-patterns.c
@@ -76,6 +76,10 @@ static gimple vect_recog_vector_vector_shift_pattern
(vec<gimple> *,
tree *, tree *);
static gimple vect_recog_divmod_pattern (vec<gimple> *,
tree *, tree *);
+
+static gimple vect_recog_mult_pattern (vec<gimple> *,
+ tree *, tree *);
+
static gimple vect_recog_mixed_size_cond_pattern (vec<gimple> *,
tree *, tree *);
static gimple vect_recog_bool_pattern (vec<gimple> *, tree *, tree *);
@@ -90,6 +94,7 @@ static vect_recog_func_ptr
vect_vect_recog_func_ptrs[NUM_PATTERNS] = {
vect_recog_rotate_pattern,
vect_recog_vector_vector_shift_pattern,
vect_recog_divmod_pattern,
+ vect_recog_mult_pattern,
vect_recog_mixed_size_cond_pattern,
vect_recog_bool_pattern};
@@ -2147,6 +2152,140 @@ vect_recog_vector_vector_shift_pattern (vec<gimple>
*stmts,
return pattern_stmt;
}
+/* Detect multiplication by constant which are postive or negatives of power 2,
+ and convert them to shift patterns.
+
+ Mult with constants that are postive power of two.
+ type a_t;
+ type b_t
+ S1: b_t = a_t * n
+
+ or
+
+ Mult with constants that are negative power of two.
+ S2: b_t = a_t * -n
+
+ Input/Output:
+
+ STMTS: Contains a stmt from which the pattern search begins,
+ i.e. the mult stmt. Convert the mult operation to LSHIFT if
+ constant operand is a power of 2.
+ type a_t, b_t
+ S1': b_t = a_t << log2 (n)
+
+ Convert the mult operation to LSHIFT and followed by a NEGATE
+ if constant operand is a negative power of 2.
+ type a_t, b_t, res_T;
+ S2': b_t = a_t << log2 (n)
+ S3': res_T = - (b_t)
+
+ Output:
+
+ * TYPE_IN: The type of the input arguments to the pattern.
+
+ * TYPE_OUT: The type of the output of this pattern.
+
+ * Return value: A new stmt that will be used to replace the multiplication
+ S1 or S2 stmt. */
+
+static gimple
+vect_recog_mult_pattern (vec<gimple> *stmts,
+ tree *type_in, tree *type_out)
+{
+ gimple last_stmt = stmts->pop ();
+ tree oprnd0, oprnd1, vectype, itype;
+ gimple pattern_stmt, def_stmt;
+ optab optab;
+ stmt_vec_info stmt_vinfo = vinfo_for_stmt (last_stmt);
+
+ if (!is_gimple_assign (last_stmt))
+ return NULL;
+
+ if (gimple_assign_rhs_code (last_stmt) != MULT_EXPR)
+ return NULL;
+
+ oprnd0 = gimple_assign_rhs1 (last_stmt);
+ oprnd1 = gimple_assign_rhs2 (last_stmt);
+ itype = TREE_TYPE (oprnd0);
+
+ if (TREE_CODE (oprnd0) != SSA_NAME
+ || TREE_CODE (oprnd1) != INTEGER_CST
+ || TREE_CODE (itype) != INTEGER_TYPE
+ || TYPE_PRECISION (itype) != GET_MODE_PRECISION (TYPE_MODE (itype)))
+ return NULL;
+
+ vectype = get_vectype_for_scalar_type (itype);
+ if (vectype == NULL_TREE)
+ return NULL;
+
+ /* If the target can handle vectorized multiplication natively,
+ don't attempt to optimize this. */
+ optab = optab_for_tree_code (MULT_EXPR, vectype, optab_default);
+ if (optab != unknown_optab)
+ {
+ machine_mode vec_mode = TYPE_MODE (vectype);
+ int icode = (int) optab_handler (optab, vec_mode);
+ if (icode != CODE_FOR_nothing)
+ return NULL;
+ }
+
+ /* If target cannot handle vector left shift then we cannot
+ optimize and bail out. */
+ optab = optab_for_tree_code (LSHIFT_EXPR, vectype, optab_vector);
+ if (!optab
+ || optab_handler (optab, TYPE_MODE (vectype)) == CODE_FOR_nothing)
+ return NULL;
+
+ /* Handle constant operands that are postive or negative powers of 2. */
+ if ( wi::exact_log2 (oprnd1) != -1 ||
+ wi::exact_log2 (wi::neg (oprnd1)) != -1)
+ {
+ tree shift;
+
+ if (wi::exact_log2 (oprnd1) != -1)
+ {
+ shift = build_int_cst (itype, wi::exact_log2 (oprnd1));
+ pattern_stmt
+ = gimple_build_assign (vect_recog_temp_ssa_var (itype, NULL),
+ LSHIFT_EXPR, oprnd0, shift);
+ }
+ else
+ {
+ /* If the target cannot handle vector NEGATE then we cannot
+ do the optimization. */
+ optab = optab_for_tree_code (NEGATE_EXPR, vectype, optab_vector);
+ if (!optab
+ || optab_handler (optab, TYPE_MODE (vectype)) == CODE_FOR_nothing)
+ return NULL;
+
+ shift = build_int_cst (itype, wi::exact_log2 (wi::neg (oprnd1)));
+ def_stmt
+ = gimple_build_assign (vect_recog_temp_ssa_var (itype, NULL),
+ LSHIFT_EXPR, oprnd0, shift);
+ new_pattern_def_seq (stmt_vinfo, def_stmt);
+ pattern_stmt
+ = gimple_build_assign (vect_recog_temp_ssa_var (itype, NULL),
+ NEGATE_EXPR, gimple_assign_lhs (def_stmt));
+ }
+
+ /* Pattern detected. */
+ if (dump_enabled_p ())
+ dump_printf_loc (MSG_NOTE, vect_location,
+ "vect_recog_mult_pattern: detected:\n");
+
+ if (dump_enabled_p ())
+ dump_gimple_stmt_loc (MSG_NOTE, vect_location, TDF_SLIM,
+ pattern_stmt,0);
+
+ stmts->safe_push (last_stmt);
+ *type_in = vectype;
+ *type_out = vectype;
+ return pattern_stmt;
+ }
+
+ return NULL;
+}
+
/* Detect a signed division by a constant that wouldn't be
otherwise vectorized:
diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index dfa8795..b490af4 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -1132,7 +1132,7 @@ extern void vect_slp_transform_bb (basic_block);
Additional pattern recognition functions can (and will) be added
in the future. */
typedef gimple (* vect_recog_func_ptr) (vec<gimple> *, tree *, tree *);
-#define NUM_PATTERNS 12
+#define NUM_PATTERNS 13
void vect_pattern_recog (loop_vec_info, bb_vec_info);
/* In tree-vectorizer.c. */
