From: Tamar Christina <tamar.christina@arm.com>
To: gcc-patches@gcc.gnu.org
Cc: nd@arm.com, rguenther@suse.de
Subject: [PATCH 1/2]middle-end: Simplify subtract where both arguments are being bitwise inverted.
Date: Thu, 16 Jun 2022 12:08:47 +0100 [thread overview]
Message-ID: <patch-15840-tamar@arm.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 1532 bytes --]
Hi All,
This adds a match.pd rule that drops the bitwwise nots when both arguments to a
subtract is inverted. i.e. for:
float g(float a, float b)
{
return ~(int)a - ~(int)b;
}
we instead generate
float g(float a, float b)
{
return (int)a - (int)b;
}
We already do a limited version of this from the fold_binary fold functions but
this makes a more general version in match.pd that applies more often.
Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.
Ok for master?
Thanks,
Tamar
gcc/ChangeLog:
* match.pd: New bit_not rule.
gcc/testsuite/ChangeLog:
* gcc.dg/subnot.c: New test.
--- inline copy of patch --
diff --git a/gcc/match.pd b/gcc/match.pd
index a59b6778f661cf9121dd3503f43472871e4da445..51b0a1b562409af535e53828a10c30b8a3e1ae2e 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1258,6 +1258,10 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(simplify
(bit_not (plus:c (bit_not @0) @1))
(minus @0 @1))
+/* (~X - ~Y) -> X - Y. */
+(simplify
+ (minus (bit_not @0) (bit_not @1))
+ (minus @0 @1))
/* ~(X - Y) -> ~X + Y. */
(simplify
diff --git a/gcc/testsuite/gcc.dg/subnot.c b/gcc/testsuite/gcc.dg/subnot.c
new file mode 100644
index 0000000000000000000000000000000000000000..d621bacd27bd3d19a010e4c9f831aa77d28bd02d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/subnot.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized" } */
+
+float g(float a, float b)
+{
+ return ~(int)a - ~(int)b;
+}
+
+/* { dg-final { scan-tree-dump-not "~" "optimized" } } */
--
[-- Attachment #2: rb15840.patch --]
[-- Type: text/plain, Size: 886 bytes --]
diff --git a/gcc/match.pd b/gcc/match.pd
index a59b6778f661cf9121dd3503f43472871e4da445..51b0a1b562409af535e53828a10c30b8a3e1ae2e 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1258,6 +1258,10 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(simplify
(bit_not (plus:c (bit_not @0) @1))
(minus @0 @1))
+/* (~X - ~Y) -> X - Y. */
+(simplify
+ (minus (bit_not @0) (bit_not @1))
+ (minus @0 @1))
/* ~(X - Y) -> ~X + Y. */
(simplify
diff --git a/gcc/testsuite/gcc.dg/subnot.c b/gcc/testsuite/gcc.dg/subnot.c
new file mode 100644
index 0000000000000000000000000000000000000000..d621bacd27bd3d19a010e4c9f831aa77d28bd02d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/subnot.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized" } */
+
+float g(float a, float b)
+{
+ return ~(int)a - ~(int)b;
+}
+
+/* { dg-final { scan-tree-dump-not "~" "optimized" } } */
next reply other threads:[~2022-06-16 11:09 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-16 11:08 Tamar Christina [this message]
2022-06-16 11:09 ` [PATCH 2/2]middle-end: Support recognition of three-way max/min Tamar Christina
2022-06-20 8:36 ` Richard Biener
2022-06-20 9:01 ` Tamar Christina
2022-06-21 13:15 ` Richard Biener
2022-06-21 13:42 ` Tamar Christina
2022-06-27 7:52 ` Richard Biener
2022-07-05 15:25 ` Tamar Christina
2022-07-12 9:39 ` Tamar Christina
2022-07-12 13:19 ` Richard Biener
2022-07-27 10:40 ` Tamar Christina
2022-07-27 11:18 ` Richard Biener
2022-08-02 8:32 ` Tamar Christina
2022-08-02 9:11 ` Richard Biener
2022-08-03 8:17 ` Tamar Christina
2022-08-03 8:25 ` Richard Biener
2022-08-03 20:41 ` H.J. Lu
2022-06-20 23:16 ` Andrew Pinski
2022-06-21 6:54 ` Richard Biener
2022-06-21 7:12 ` Tamar Christina
2022-06-20 8:03 ` [PATCH 1/2]middle-end: Simplify subtract where both arguments are being bitwise inverted Richard Biener
2022-06-20 8:18 ` Richard Sandiford
2022-06-20 8:49 ` Tamar Christina
2022-06-21 7:43 ` Richard Biener
2022-08-03 15:13 ` Tamar Christina
2022-08-04 6:58 ` Richard Biener
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