From c9ccc3961f5b8d333f5081b377cd9ee9e33079f7 Mon Sep 17 00:00:00 2001
From: Andi Kleen <ak@gcc.gnu.org>
Date: Thu, 1 Aug 2024 20:10:27 -0700
Subject: [PATCH] Support if conversion for switches
The gimple-if-to-switch pass converts if statements with
multiple equal checks on the same value to a switch. This breaks
vectorization which cannot handle switches.
Teach the tree-if-conv pass used by the vectorizer to handle
simple switch statements, like those created by if-to-switch earlier.
These are switches that only have a single non default block,
They are handled similar to COND in if conversion.
This makes the vect-bitfield-read-1-not test fail. The test
checks for a bitfield analysis failing, but it actually
relied on the ifcvt erroring out early because the test
is using a switch. The if conversion still does not
work because the switch is not in a form that this
patch can handle, but it fails much later and the bitfield
analysis succeeds, which makes the test fail. I marked
it xfail because it doesn't seem to be testing what it wants
to test.
PR tree-optimization/115866
gcc/ChangeLog:
* tree-if-conv.cc (if_convertible_switch_p): New function.
(if_convertible_stmt_p): Check for switch.
(get_loop_body_in_if_conv_order): Handle switch.
(predicate_bbs): Likewise.
(predicate_statements): Likewise.
(remove_conditions_and_labels): Likewise.
(ifcvt_split_critical_edges): Likewise.
(ifcvt_local_dce): Likewise.
gcc/testsuite/ChangeLog:
* gcc.dg/vect/vect-switch-ifcvt-1.c: New test.
* gcc.dg/vect/vect-switch-ifcvt-2.c: New test.
* gcc.dg/vect/vect-switch-search-line-fast.c: New test.
* gcc.dg/vect/vect-bitfield-read-1-not.c: Change to xfail.
---
.../gcc.dg/vect/vect-bitfield-read-1-not.c | 2 +-
.../gcc.dg/vect/vect-switch-ifcvt-1.c | 115 ++++++++++++++++++
.../gcc.dg/vect/vect-switch-ifcvt-2.c | 49 ++++++++
.../vect/vect-switch-search-line-fast.c | 17 +++
gcc/tree-if-conv.cc | 93 +++++++++++++-
5 files changed, 270 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-switch-ifcvt-1.c
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-switch-ifcvt-2.c
create mode 100644 gcc/testsuite/gcc.dg/vect/vect-switch-search-line-fast.c
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-1-not.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-1-not.c
index 0d91067ebb27..85f4de8464a5 100644
--- a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-1-not.c
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-1-not.c
@@ -55,6 +55,6 @@ int main (void)
return 0;
}
-/* { dg-final { scan-tree-dump-not "Bitfield OK to lower." "ifcvt" } } */
+/* { dg-final { scan-tree-dump-times "Bitfield OK to lower." 0 "ifcvt" { xfail *-*-* } } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-switch-ifcvt-1.c b/gcc/testsuite/gcc.dg/vect/vect-switch-ifcvt-1.c
new file mode 100644
index 000000000000..f5352ef8ed7a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-switch-ifcvt-1.c
@@ -0,0 +1,115 @@
+/* { dg-require-effective-target vect_int } */
+#include "tree-vect.h"
+
+extern void abort (void);
+
+int
+f1 (char *s)
+{
+ int c = 0;
+ int i;
+ for (i = 0; i < 64; i++)
+ {
+ switch (*s)
+ {
+ case ',':
+ case '|':
+ c++;
+ }
+ s++;
+ }
+ return c;
+}
+
+int
+f2 (char *s)
+{
+ int c = 0;
+ int i;
+ for (i = 0; i < 64; i++)
+ {
+ if (*s != '#')
+ {
+ switch (*s)
+ {
+ case ',':
+ case '|':
+ c++;
+ }
+ }
+ s++;
+ }
+ return c;
+}
+
+int
+f3 (char *s)
+{
+ int c = 0;
+ int i;
+ for (i = 0; i < 64; i++)
+ {
+ if (*s != '#')
+ if (*s == ',' || *s == '|' || *s == '@' || *s == '*')
+ c++;
+ s++;
+ }
+ return c;
+}
+
+
+int
+f4 (char *s)
+{
+ int c = 0;
+ int i;
+ for (i = 0; i < 64; i++)
+ {
+ if (*s == ',' || *s == '|' || *s == '@' || *s == '*')
+ c++;
+ s++;
+ }
+ return c;
+}
+
+#define CHECK(f, str, res) \
+ __builtin_strcpy(buf, str); n = f(buf); if (n != res) abort();
+
+int
+main ()
+{
+ int n;
+ char buf[64];
+
+ __builtin_memset (buf, 0, sizeof buf);
+
+ check_vect ();
+
+ CHECK (f1, ",,,,,,,,,,", 10);
+ CHECK (f1, "||||||||||", 10);
+ CHECK (f1, "aaaaaaaaaa", 0);
+ CHECK (f1, "", 0);
+ CHECK (f1, ",|,|xxxxxx", 4);
+
+ CHECK (f2, ",,,,,,,,,,", 10);
+ CHECK (f2, "||||||||||", 10);
+ CHECK (f2, "aaaaaaaaaa", 0);
+ CHECK (f2, "", 0);
+ CHECK (f2, ",|,|xxxxxx", 4);
+
+ CHECK (f3, ",,,,,,,,,,", 10);
+ CHECK (f3, "||||||||||", 10);
+ CHECK (f3, "aaaaaaaaaa", 0);
+ CHECK (f3, "", 0);
+ CHECK (f3, ",|,|xxxxxx", 4);
+
+ CHECK (f4, ",,,,,,,,,,", 10);
+ CHECK (f4, "||||||||||", 10);
+ CHECK (f4, "aaaaaaaaaa", 0);
+ CHECK (f4, "", 0);
+ CHECK (f4, ",|,|xxxxxx", 4);
+
+ return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 4 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-switch-ifcvt-2.c b/gcc/testsuite/gcc.dg/vect/vect-switch-ifcvt-2.c
new file mode 100644
index 000000000000..f0fcb43e1770
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-switch-ifcvt-2.c
@@ -0,0 +1,49 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_int } */
+
+/* Check for cases currently not supported by switch tree if conversion. */
+
+int
+f1 (char *s)
+{
+ int c = 0;
+ int i;
+ for (i = 0; i < 64; i++)
+ {
+ switch (*s)
+ {
+ case ',':
+ case '|':
+ c++;
+ break;
+ case '^':
+ c += 2;
+ break;
+ }
+ s++;
+ }
+ return c;
+}
+
+int
+f2 (char *s)
+{
+ int c = 0;
+ int i;
+ for (i = 0; i < 64; i++)
+ {
+ switch (*s)
+ {
+ case ',':
+ case '|':
+ c++;
+ /*fallthrough*/
+ default:
+ c+=2;
+ }
+ s++;
+ }
+ return c;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 0 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-switch-search-line-fast.c b/gcc/testsuite/gcc.dg/vect/vect-switch-search-line-fast.c
new file mode 100644
index 000000000000..15f3a4ef38a7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-switch-search-line-fast.c
@@ -0,0 +1,17 @@
+/* PR116126 -- once this works use this version in libcpp/lex.c.
+ This also requires working value range propagation for s/end. */
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_int } */
+
+const unsigned char *search_line_fast2 (const unsigned char *s,
+ const unsigned char *end)
+{
+ while (s < end) {
+ if (*s == '\n' || *s == '\r' || *s == '\\' || *s == '?')
+ break;
+ s++;
+ }
+ return s;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" { xfail *-*-* } } } */
diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
index 57992b6decaf..5aac65cfbd18 100644
--- a/gcc/tree-if-conv.cc
+++ b/gcc/tree-if-conv.cc
@@ -124,6 +124,7 @@ along with GCC; see the file COPYING3. If not see
#include "tree-vectorizer.h"
#include "tree-eh.h"
#include "cgraph.h"
+#include "print-tree.h"
/* For lang_hooks.types.type_for_mode. */
#include "langhooks.h"
@@ -1082,11 +1083,35 @@ if_convertible_gimple_assign_stmt_p (gimple *stmt,
return true;
}
+/* Return true when SW switch statement is equivalent to cond, that
+ all non default labels point to the same label.
+
+ Fallthrough is not checked for and could even happen
+ with cond (using goto), so is handled.
+
+ This is intended for switches created by the if-switch-conversion
+ pass, but can handle some programmer supplied cases too. */
+
+static bool
+if_convertible_switch_p (gswitch *sw)
+{
+ if (gimple_switch_num_labels (sw) <= 1)
+ return false;
+ tree label = CASE_LABEL (gimple_switch_label (sw, 1));
+ for (unsigned i = 1; i < gimple_switch_num_labels (sw); i++)
+ {
+ if (CASE_LABEL (gimple_switch_label (sw, i)) != label)
+ return false;
+ }
+ return true;
+}
+
/* Return true when STMT is if-convertible.
A statement is if-convertible if:
- it is an if-convertible GIMPLE_ASSIGN,
- it is a GIMPLE_LABEL or a GIMPLE_COND,
+ - it is a switch equivalent to COND
- it is builtins call,
- it is a call to a function with a SIMD clone. */
@@ -1100,6 +1125,9 @@ if_convertible_stmt_p (gimple *stmt, vec<data_reference_p> refs)
case GIMPLE_COND:
return true;
+ case GIMPLE_SWITCH:
+ return if_convertible_switch_p (as_a <gswitch *> (stmt));
+
case GIMPLE_ASSIGN:
return if_convertible_gimple_assign_stmt_p (stmt, refs);
@@ -1327,6 +1355,7 @@ get_loop_body_in_if_conv_order (const class loop *loop)
case GIMPLE_CALL:
case GIMPLE_DEBUG:
case GIMPLE_COND:
+ case GIMPLE_SWITCH:
gimple_set_uid (gsi_stmt (gsi), 0);
break;
default:
@@ -1426,6 +1455,58 @@ predicate_bbs (loop_p loop)
cond = NULL_TREE;
}
+ /* Assumes the limited COND like switches checked for earlier. */
+ else if (gswitch *sw = safe_dyn_cast <gswitch *> (*gsi_last_bb (bb)))
+ {
+ location_t loc = gimple_location (*gsi_last_bb (bb));
+
+ tree default_label = CASE_LABEL (gimple_switch_default_label (sw));
+ tree cond_label = CASE_LABEL (gimple_switch_label (sw, 1));
+
+ edge false_edge = find_edge (bb, label_to_block (cfun, default_label));
+ edge true_edge = find_edge (bb, label_to_block (cfun, cond_label));
+
+ /* Create chain of switch tests for each case. */
+ tree switch_cond = NULL_TREE;
+ tree index = gimple_switch_index (sw);
+ for (unsigned i = 1; i < gimple_switch_num_labels (sw); i++)
+ {
+ tree label = gimple_switch_label (sw, i);
+ tree case_cond;
+ if (CASE_HIGH (label))
+ {
+ tree low = build2_loc (loc, GE_EXPR,
+ boolean_type_node,
+ index, CASE_LOW (label));
+ tree high = build2_loc (loc, LE_EXPR,
+ boolean_type_node,
+ index, CASE_HIGH (label));
+ case_cond = build2_loc (loc, TRUTH_AND_EXPR,
+ boolean_type_node,
+ low, high);
+ }
+ else
+ case_cond = build2_loc (loc, EQ_EXPR,
+ boolean_type_node,
+ index,
+ CASE_LOW (gimple_switch_label (sw, i)));
+ if (i > 1)
+ switch_cond = build2_loc (loc, TRUTH_OR_EXPR,
+ boolean_type_node,
+ case_cond, switch_cond);
+ else
+ switch_cond = case_cond;
+ }
+
+ add_to_dst_predicate_list (loop, true_edge, unshare_expr (cond),
+ unshare_expr (switch_cond));
+ switch_cond = build1_loc (loc, TRUTH_NOT_EXPR, boolean_type_node,
+ unshare_expr (switch_cond));
+ add_to_dst_predicate_list (loop, false_edge,
+ unshare_expr (cond), switch_cond);
+ cond = NULL_TREE;
+ }
+
/* If current bb has only one successor, then consider it as an
unconditional goto. */
if (single_succ_p (bb))
@@ -2852,9 +2933,9 @@ predicate_statements (loop_p loop)
}
}
-/* Remove all GIMPLE_CONDs and GIMPLE_LABELs of all the basic blocks
- other than the exit and latch of the LOOP. Also resets the
- GIMPLE_DEBUG information. */
+/* Remove all GIMPLE_CONDs and GIMPLE_LABELs and GIMPLE_SWITCH of all
+ the basic blocks other than the exit and latch of the LOOP. Also
+ resets the GIMPLE_DEBUG information. */
static void
remove_conditions_and_labels (loop_p loop)
@@ -2875,6 +2956,7 @@ remove_conditions_and_labels (loop_p loop)
{
case GIMPLE_COND:
case GIMPLE_LABEL:
+ case GIMPLE_SWITCH:
gsi_remove (&gsi, true);
break;
@@ -3265,7 +3347,8 @@ ifcvt_split_critical_edges (class loop *loop, bool aggressive_if_conv)
continue;
/* Skip basic blocks not ending with conditional branch. */
- if (!safe_is_a <gcond *> (*gsi_last_bb (bb)))
+ if (!safe_is_a <gcond *> (*gsi_last_bb (bb))
+ && !safe_is_a <gswitch *> (*gsi_last_bb (bb)))
continue;
FOR_EACH_EDGE (e, ei, bb->succs)
@@ -3330,7 +3413,7 @@ ifcvt_local_dce (class loop *loop)
continue;
}
code = gimple_code (stmt);
- if (code == GIMPLE_COND || code == GIMPLE_CALL)
+ if (code == GIMPLE_COND || code == GIMPLE_CALL || code == GIMPLE_SWITCH)
{
gimple_set_plf (stmt, GF_PLF_2, true);
worklist.safe_push (stmt);
--
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