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Switch conversion: support any ax + b transformation (PR tree-optimiz…

…ation/84436).

2018-10-24  Martin Liska  <mliska@suse.cz>

	PR tree-optimization/84436
	* tree-switch-conversion.c (switch_conversion::contains_same_values_p):
	Remove.
	(switch_conversion::contains_linear_function_p): New.
	(switch_conversion::build_one_array): Support linear
	transformation on input.
	* tree-switch-conversion.h (struct switch_conversion): Add
	contains_linear_function_p declaration.
2018-10-24  Martin Liska  <mliska@suse.cz>

	PR tree-optimization/84436
	* gcc.dg/tree-ssa/pr84436-1.c: New test.
	* gcc.dg/tree-ssa/pr84436-2.c: New test.
	* gcc.dg/tree-ssa/pr84436-3.c: New test.
	* gcc.dg/tree-ssa/pr84436-4.c: New test.
	* gcc.dg/tree-ssa/pr84436-5.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@265463 138bc75d-0d04-0410-961f-82ee72b054a4
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marxin
marxin committed Oct 24, 2018
1 parent 09c1716 commit 570c6c2ee57d1250468e5dde121d196f730732e1
@@ -1,3 +1,14 @@
2018-10-24 Martin Liska <mliska@suse.cz>

PR tree-optimization/84436
* tree-switch-conversion.c (switch_conversion::contains_same_values_p):
Remove.
(switch_conversion::contains_linear_function_p): New.
(switch_conversion::build_one_array): Support linear
transformation on input.
* tree-switch-conversion.h (struct switch_conversion): Add
contains_linear_function_p declaration.

2018-10-24 Richard Biener <rguenther@suse.de>

* varasm.c (const_hash_1): Return hash of ADDR_EXPR
@@ -1,3 +1,12 @@
2018-10-24 Martin Liska <mliska@suse.cz>

PR tree-optimization/84436
* gcc.dg/tree-ssa/pr84436-1.c: New test.
* gcc.dg/tree-ssa/pr84436-2.c: New test.
* gcc.dg/tree-ssa/pr84436-3.c: New test.
* gcc.dg/tree-ssa/pr84436-4.c: New test.
* gcc.dg/tree-ssa/pr84436-5.c: New test.

2018-10-24 Ilya Leoshkevich <iii@linux.ibm.com>

* gcc.target/s390/20181024-1.c: New test.
@@ -0,0 +1,36 @@
/* PR tree-optimization/84436 */
/* { dg-options "-O2 -fdump-tree-switchconv -fdump-tree-optimized" } */
/* { dg-do run } */

int
__attribute__ ((noipa))
foo (int how)
{
switch (how) {
case 2: how = 205; break; /* how = 100 * index + 5 */
case 3: how = 305; break;
case 4: how = 405; break;
case 5: how = 505; break;
case 6: how = 605; break;
}
return how;
}

int main()
{
if (foo (2) != 205)
__builtin_abort ();

if (foo (6) != 605)
__builtin_abort ();

if (foo (123) != 123)
__builtin_abort ();

return 0;
}


/* { dg-final { scan-tree-dump-times "100 \\*" 1 "switchconv" } } */
/* { dg-final { scan-tree-dump-times ".* \\+ 5" 1 "switchconv" } } */
/* { dg-final { scan-tree-dump-not "switch" "optimized" } } */
@@ -0,0 +1,67 @@
/* PR tree-optimization/84436 */
/* { dg-options "-O2 -fdump-tree-switchconv -fdump-tree-optimized" } */

char
lowerit(char a)
{
switch (a)
{
default:
return a;
case 'A':
return 'a';
case 'B':
return 'b';
case 'C':
return 'c';
case 'D':
return 'd';
case 'E':
return 'e';
case 'F':
return 'f';
case 'G':
return 'g';
case 'H':
return 'h';
case 'I':
return 'i';
case 'J':
return 'j';
case 'K':
return 'k';
case 'L':
return 'l';
case 'M':
return 'm';
case 'N':
return 'n';
case 'O':
return 'o';
case 'P':
return 'p';
case 'Q':
return 'q';
case 'R':
return 'r';
case 'S':
return 's';
case 'T':
return 't';
case 'U':
return 'u';
case 'V':
return 'v';
case 'W':
return 'w';
case 'X':
return 'x';
case 'Y':
return 'y';
case 'Z':
return 'z';
}
}

/* { dg-final { scan-tree-dump-times "a_.*\\+ 32" 1 "switchconv" } } */
/* { dg-final { scan-tree-dump-not "switch" "optimized" } } */
@@ -0,0 +1,24 @@
/* PR tree-optimization/84436 */
/* { dg-options "-O2 -fdump-tree-switchconv -fdump-tree-optimized" } */

enum a { b, c, d };
int e;
void h(enum a);

void f() {
enum a g;
switch (e) {
case '1':
g = b;
break;
case '2':
g = c;
break;
case '3':
g = d;
}
h(g);
}

/* { dg-final { scan-tree-dump-times ".* \\+ 4294967247" 1 "switchconv" } } */
/* { dg-final { scan-tree-dump-not "switch" "optimized" } } */
@@ -0,0 +1,38 @@
/* PR tree-optimization/84436 */
/* { dg-options "-O2 -fdump-tree-switchconv -fdump-tree-optimized" } */
/* { dg-do run } */

enum E
{
A, B, C,
};

int
__attribute__ ((noipa))
foo(enum E e)
{
switch (e)
{
case A: return 0;
case B: return 1;
case C: return 2;
}

return -1;
}

int main()
{
if (foo (A) != 0)
__builtin_abort ();

if (foo (B) != 1)
__builtin_abort ();

if (foo (C) != 2)
__builtin_abort ();

return 0;
}

/* { dg-final { scan-tree-dump-not "switch" "optimized" } } */
@@ -0,0 +1,38 @@
/* PR tree-optimization/84436 */
/* { dg-options "-O2 -fdump-tree-switchconv -fdump-tree-optimized" } */
/* { dg-do run } */

char
__attribute__ ((noipa))
foo (char how)
{
switch (how) {
case -4: how = 96; break;
case -3: how = -120; break;
case -2: how = -80; break;
case -1: how = -40; break;
case 0: how = 0; break;
case 1: how = 40; break;
}
return how;
}

int main()
{
if (foo (-4) != 96)
__builtin_abort ();

if (foo (-3) != -120)
__builtin_abort ();

if (foo (0) != 0)
__builtin_abort ();

if (foo (123) != 123)
__builtin_abort ();

return 0;
}

/* { dg-final { scan-tree-dump-times "40 *\\*" 1 "switchconv" } } */
/* { dg-final { scan-tree-dump-not "switch" "optimized" } } */
@@ -44,6 +44,7 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
#include "gimplify.h"
#include "gimple-iterator.h"
#include "gimplify-me.h"
#include "gimple-fold.h"
#include "tree-cfg.h"
#include "cfgloop.h"
#include "alloc-pool.h"
@@ -439,25 +440,63 @@ switch_conversion::build_constructors ()
}
}

/* If all values in the constructor vector are the same, return the value.
Otherwise return NULL_TREE. Not supposed to be called for empty
vectors. */
/* If all values in the constructor vector are products of a linear function
a * x + b, then return true. When true, COEFF_A and COEFF_B and
coefficients of the linear function. Note that equal values are special
case of a linear function with a and b equal to zero. */

tree
switch_conversion::contains_same_values_p (vec<constructor_elt, va_gc> *vec)
bool
switch_conversion::contains_linear_function_p (vec<constructor_elt, va_gc> *vec,
wide_int *coeff_a,
wide_int *coeff_b)
{
unsigned int i;
tree prev = NULL_TREE;
constructor_elt *elt;

gcc_assert (vec->length () >= 2);

/* Let's try to find any linear function a * x + y that can apply to
given values. 'a' can be calculated as follows:
a = (y2 - y1) / (x2 - x1) where x2 - x1 = 1 (consecutive case indices)
a = y2 - y1
and
b = y2 - a * x2
*/

tree elt0 = (*vec)[0].value;
tree elt1 = (*vec)[1].value;

if (TREE_CODE (elt0) != INTEGER_CST || TREE_CODE (elt1) != INTEGER_CST)
return false;

wide_int range_min = wi::to_wide (fold_convert (TREE_TYPE (elt0),
m_range_min));
wide_int y1 = wi::to_wide (elt0);
wide_int y2 = wi::to_wide (elt1);
wide_int a = y2 - y1;
wide_int b = y2 - a * (range_min + 1);

/* Verify that all values fulfill the linear function. */
FOR_EACH_VEC_SAFE_ELT (vec, i, elt)
{
if (!prev)
prev = elt->value;
else if (!operand_equal_p (elt->value, prev, OEP_ONLY_CONST))
return NULL_TREE;
if (TREE_CODE (elt->value) != INTEGER_CST)
return false;

wide_int value = wi::to_wide (elt->value);
if (a * range_min + b != value)
return false;

++range_min;
}
return prev;

*coeff_a = a;
*coeff_b = b;

return true;
}

/* Return type which should be used for array elements, either TYPE's
@@ -551,7 +590,7 @@ void
switch_conversion::build_one_array (int num, tree arr_index_type,
gphi *phi, tree tidx)
{
tree name, cst;
tree name;
gimple *load;
gimple_stmt_iterator gsi = gsi_for_stmt (m_switch);
location_t loc = gimple_location (m_switch);
@@ -561,9 +600,27 @@ switch_conversion::build_one_array (int num, tree arr_index_type,
name = copy_ssa_name (PHI_RESULT (phi));
m_target_inbound_names[num] = name;

cst = contains_same_values_p (m_constructors[num]);
if (cst)
load = gimple_build_assign (name, cst);
wide_int coeff_a, coeff_b;
bool linear_p = contains_linear_function_p (m_constructors[num], &coeff_a,
&coeff_b);
if (linear_p)
{
if (dump_file && coeff_a.to_uhwi () > 0)
fprintf (dump_file, "Linear transformation with A = %" PRId64
" and B = %" PRId64 "\n", coeff_a.to_shwi (),
coeff_b.to_shwi ());

tree t = unsigned_type_for (TREE_TYPE (m_index_expr));
gimple_seq seq = NULL;
tree tmp = gimple_convert (&seq, t, m_index_expr);
tree tmp2 = gimple_build (&seq, MULT_EXPR, t,
wide_int_to_tree (t, coeff_a), tmp);
tree tmp3 = gimple_build (&seq, PLUS_EXPR, t, tmp2,
wide_int_to_tree (t, coeff_b));
tree tmp4 = gimple_convert (&seq, TREE_TYPE (name), tmp3);
gsi_insert_seq_before (&gsi, seq, GSI_SAME_STMT);
load = gimple_build_assign (name, tmp4);
}
else
{
tree array_type, ctor, decl, value_type, fetch, default_type;
@@ -733,10 +733,12 @@ struct switch_conversion
order of phi nodes. */
void build_constructors ();

/* If all values in the constructor vector are the same, return the value.
Otherwise return NULL_TREE. Not supposed to be called for empty
vectors. */
tree contains_same_values_p (vec<constructor_elt, va_gc> *vec);
/* If all values in the constructor vector are products of a linear function
a * x + b, then return true. When true, COEFF_A and COEFF_B and
coefficients of the linear function. Note that equal values are special
case of a linear function with a and b equal to zero. */
bool contains_linear_function_p (vec<constructor_elt, va_gc> *vec,
wide_int *coeff_a, wide_int *coeff_b);

/* Return type which should be used for array elements, either TYPE's
main variant or, for integral types, some smaller integral type

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