From: Haochen Gui <guihaoc@gcc.gnu.org>
Date: Wed, 11 May 2022 01:19:52 +0000 (+0800)
Subject: This patch adds a combine pattern for "CA minus one". The SImode "CA minus one" can... 
X-Git-Tag: basepoints/gcc-14~6625
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a174dc1a7f2bf0a71475ff633b130a60c0c3ff4a;p=thirdparty%2Fgcc.git

This patch adds a combine pattern for "CA minus one". The SImode "CA minus one" can be converted to DImode as CA only has two values (0 or 1).

gcc/
	PR target/95737
	* config/rs6000/rs6000.md (*subfsi3_carry_in_xx_64): New.

gcc/testsuite/
	PR target/95737
	* gcc.target/powerpc/pr95737.c: New.
---

diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index bf85baa5370..3eca448a262 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -2344,6 +2344,19 @@
   "subfe %0,%0,%0"
   [(set_attr "type" "add")])
 
+(define_insn_and_split "*subfsi3_carry_in_xx_64"
+  [(set (match_operand:DI 0 "gpc_reg_operand" "=r")
+	(sign_extend:DI (plus:SI (reg:SI CA_REGNO)
+				 (const_int -1))))]
+  "TARGET_POWERPC64"
+  "#"
+  "&&1"
+  [(parallel [(set (match_dup 0)
+		   (plus:DI (reg:DI CA_REGNO)
+			    (const_int -1)))
+	      (clobber (reg:DI CA_REGNO))])]
+  ""
+)
 
 (define_insn "@neg<mode>2"
   [(set (match_operand:GPR 0 "gpc_reg_operand" "=r")
diff --git a/gcc/testsuite/gcc.target/powerpc/pr95737.c b/gcc/testsuite/gcc.target/powerpc/pr95737.c
new file mode 100644
index 00000000000..324694fa9a1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr95737.c
@@ -0,0 +1,11 @@
+/* PR target/95737 */
+/* { dg-do compile } */
+/* Disable isel for P9 and later.  */
+/* { dg-options "-O2 -mno-isel" } */
+/* { dg-final { scan-assembler-not {\mextsw\M} } } */
+
+
+unsigned long negativeLessThan (unsigned long a, unsigned long b)
+{
+   return -(a < b);
+}