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Prefer bit-test over the jump table.

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gcc/ChangeLog:

	PR tree-optimization/97736
	* tree-switch-conversion.c (switch_decision_tree::analyze_switch_statement):
	Prefer bit tests.

gcc/testsuite/ChangeLog:

	PR tree-optimization/97736
	* gcc.dg/tree-ssa/switch-1.c: Prefer bit tests.
	* g++.dg/tree-ssa/pr97736.C: New test.
This commit is contained in:
Martin Liska 2020-11-09 14:26:04 +01:00
parent d12603b746
commit 5e303cdee1
3 changed files with 20 additions and 8 deletions
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12
gcc/testsuite/g++.dg/tree-ssa/pr97736.C Normal file
View file

@ -0,0 +1,12 @@
/* PR tree-optimization/97736 */
/* { dg-do compile { target { { x86_64-*-* aarch64-*-* ia64-*-* powerpc64-*-* } && lp64 } } } */
/* { dg-options "-O2 -fdump-tree-switchlower1" } */
bool is_vowel(char c) {
switch (c)
case'a':case'e':case'i':case'o':case'u':
return true;
return false;
}
/* { dg-final { scan-tree-dump ";; GIMPLE switch case clusters: BT:97-117" "switchlower1" } } */

6
gcc/testsuite/gcc.dg/tree-ssa/switch-1.c
View file

@ -54,7 +54,7 @@ int foo3 (int x)
}
}
/* { dg-final { scan-tree-dump ";; GIMPLE switch case clusters: JT:0-62" "switchlower1" } } */
/* { dg-final { scan-tree-dump ";; GIMPLE switch case clusters: BT:0-62" "switchlower1" } } */
int foo4 (int x)
{
@ -77,7 +77,7 @@ int foo4 (int x)
}
}
/* { dg-final { scan-tree-dump ";; GIMPLE switch case clusters: -100 JT:10-62 600-700" "switchlower1" } } */
/* { dg-final { scan-tree-dump ";; GIMPLE switch case clusters: -100 BT:10-62 600-700" "switchlower1" } } */
int foo5 (int x)
{
@ -107,4 +107,4 @@ int foo5 (int x)
}
}
/* { dg-final { scan-tree-dump ";; GIMPLE switch case clusters: JT:10-62 600-700 JT:1000-1021 111111" "switchlower1" } } */
/* { dg-final { scan-tree-dump ";; GIMPLE switch case clusters: BT:10-62 600-700 JT:1000-1021 111111" "switchlower1" } } */

10
gcc/tree-switch-conversion.c
View file

@ -1743,10 +1743,10 @@ switch_decision_tree::analyze_switch_statement ()
reset_out_edges_aux (m_switch);
/* Find jump table clusters. */
vec<cluster *> output = jump_table_cluster::find_jump_tables (clusters);
/* Find bit-test clusters. */
vec<cluster *> output = bit_test_cluster::find_bit_tests (clusters);
/* Find bit test clusters. */
/* Find jump table clusters. */
vec<cluster *> output2;
auto_vec<cluster *> tmp;
output2.create (1);
@ -1759,7 +1759,7 @@ switch_decision_tree::analyze_switch_statement ()
{
if (!tmp.is_empty ())
{
vec<cluster *> n = bit_test_cluster::find_bit_tests (tmp);
vec<cluster *> n = jump_table_cluster::find_jump_tables (tmp);
output2.safe_splice (n);
n.release ();
tmp.truncate (0);
@ -1773,7 +1773,7 @@ switch_decision_tree::analyze_switch_statement ()
/* We still can have a temporary vector to test. */
if (!tmp.is_empty ())
{
vec<cluster *> n = bit_test_cluster::find_bit_tests (tmp);
vec<cluster *> n = jump_table_cluster::find_jump_tables (tmp);
output2.safe_splice (n);
n.release ();
}