On December 8, 2020 2:35:35 PM GMT+01:00, "Martin Liška" <mli...@suse.cz> wrote:
>We must be careful which edge we follow for conditions
>of a negative form (index != 2).
>
>Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>
>Ready to be installed?
Ok.
Richard.
>Thanks,
>Martin
>
>gcc/ChangeLog:
>
> PR tree-optimization/98182
> * gimple-if-to-switch.cc (pass_if_to_switch::execute): Request
> chain linkage through false edges only.
>
>gcc/testsuite/ChangeLog:
>
> PR tree-optimization/98182
> * gcc.dg/tree-ssa/if-to-switch-10.c: New test.
> * gcc.dg/tree-ssa/pr98182.c: New test.
>---
> gcc/gimple-if-to-switch.cc | 6 +++
> .../gcc.dg/tree-ssa/if-to-switch-10.c | 44 +++++++++++++++++++
> gcc/testsuite/gcc.dg/tree-ssa/pr98182.c | 18 ++++++++
> 3 files changed, 68 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/if-to-switch-10.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr98182.c
>
>diff --git a/gcc/gimple-if-to-switch.cc b/gcc/gimple-if-to-switch.cc
>index 8e1043ae7c4..311f6f6ac97 100644
>--- a/gcc/gimple-if-to-switch.cc
>+++ b/gcc/gimple-if-to-switch.cc
>@@ -522,6 +522,12 @@ pass_if_to_switch::execute (function *fun)
> if (!info2 || info->m_ranges[0].exp != info2->m_ranges[0].exp)
> break;
>
>+ /* It is important that the blocks are linked through
>FALSE_EDGE.
>+ For an expression of index != VALUE, true and false edges
>+ are flipped. */
>+ if (info2->m_false_edge != e)
>+ break;
>+
> chain->m_entries.safe_push (info2);
> bitmap_set_bit (seen_bbs, e->src->index);
> info = info2;
>diff --git a/gcc/testsuite/gcc.dg/tree-ssa/if-to-switch-10.c
>b/gcc/testsuite/gcc.dg/tree-ssa/if-to-switch-10.c
>new file mode 100644
>index 00000000000..7b8da1c9f3c
>--- /dev/null
>+++ b/gcc/testsuite/gcc.dg/tree-ssa/if-to-switch-10.c
>@@ -0,0 +1,44 @@
>+/* { dg-do compile } */
>+/* { dg-options "-O2 -fdump-tree-iftoswitch-optimized" } */
>+
>+int global;
>+int foo ();
>+
>+int main(int argc, char **argv)
>+{
>+ if (argc != 1)
>+ {
>+ if (argc != 2)
>+ {
>+ if (argc == 3)
>+ {
>+ foo ();
>+ foo ();
>+ }
>+ else if (argc == 4)
>+ {
>+ foo ();
>+ }
>+ else if (argc == 5)
>+ {
>+ global = 2;
>+ }
>+ else
>+ global -= 123;
>+ }
>+ else
>+ {
>+ global += 1;
>+ }
>+ }
>+ else
>+ foo ();
>+
>+
>+ global -= 12;
>+ return 0;
>+}
>+
>+/* { dg-final { scan-tree-dump "Canonical GIMPLE case clusters: 1 2 3
>4 5" "iftoswitch" } } */
>+/* { dg-final { scan-tree-dump "Condition chain with \[^\n\r]\* BBs
>transformed into a switch statement." "iftoswitch" } } */
>+
>diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr98182.c
>b/gcc/testsuite/gcc.dg/tree-ssa/pr98182.c
>new file mode 100644
>index 00000000000..29a547e3788
>--- /dev/null
>+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr98182.c
>@@ -0,0 +1,18 @@
>+/* PR tree-optimization/98182 */
>+/* { dg-do compile } */
>+/* { dg-options "-O1 --param case-values-threshold=1
>-fdump-tree-iftoswitch-optimized" } */
>+
>+int global;
>+int foo ();
>+
>+int main(int argc, char **argv)
>+{
>+ if (argc != 1)
>+ __builtin_abort ();
>+ else if (argc != 2)
>+ __builtin_abort ();
>+ else
>+ return 0;
>+}
>+
>+/* { dg-final { scan-tree-dump-not "Condition chain" "iftoswitch" } }
>*/
