From: Roger Sayle <roger@nextmovesoftware.com>
Date: Sun, 5 Jul 2026 20:19:17 +0000 (+0100)
Subject: aarch64: [PR126094] Update aarch64_cmtst* patterns for new simplifications.
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=88752b86ff1af4589c61d5bd8592b17e481ab596;p=thirdparty%2Fgcc.git

aarch64: [PR126094] Update aarch64_cmtst* patterns for new simplifications.

The recent patch to simplify/canonicalize (not (neg (eq x y))) as
(neg (ne x y)) [when the relevant STORE_FLAG_VALUE is 1] causes
aarch64's aarch64_cmtst* patterns to fail as they were expecting
the old canonical RTL.  This patch adds the new canonical forms
to aarch64-simd.md which corrects the testsuite failure of
gcc.target/aarch64/mvn-cmeq0-1.c.

Sorry for any inconvenience.

2026-07-05  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
	PR target/126094
	* config/aarch64/aarch64-simd.md (aarch64_cmtst<mode><vczle><vczbe>):
	Update pattern to match recent RTL simplification.
	(*aarch64_cmtst<mode><vczle><vczbe>): Preserve the original.
	(*aarch64_cmtst_same_<mode><vczle><vczbe>): Additional variant.
---

diff --git a/gcc/config/aarch64/aarch64-simd.md b/gcc/config/aarch64/aarch64-simd.md
index 94fb49a338b..23a8a47263a 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -8002,13 +8002,23 @@
 
 ;; cmtst
 
+(define_insn "aarch64_cmtst<mode><vczle><vczbe>"
+  [(set (match_operand:<V_INT_EQUIV> 0 "register_operand" "=w")
+	(neg:<V_INT_EQUIV>
+	  (ne:<V_INT_EQUIV>
+	    (and:VDQ_I
+	      (match_operand:VDQ_I 1 "register_operand" "w")
+	      (match_operand:VDQ_I 2 "register_operand" "w"))
+	    (match_operand:VDQ_I 3 "aarch64_simd_imm_zero"))))
+  ]
+  "TARGET_SIMD"
+  "cmtst\t%<v>0<Vmtype>, %<v>1<Vmtype>, %<v>2<Vmtype>"
+  [(set_attr "type" "neon_tst<q>")]
+)
 ;; Although neg (ne (and x y) 0) is the natural way of expressing a cmtst,
-;; we don't have any insns using ne, and aarch64_vcond outputs
-;; not (neg (eq (and x y) 0))
-;; which is rewritten by simplify_rtx as
-;; plus (eq (and x y) 0) -1.
+;; earlier versions of GCC simplified this as plus (eq (and x y) 0) -1.
 
-(define_insn "aarch64_cmtst<mode><vczle><vczbe>"
+(define_insn "*aarch64_cmtst<mode><vczle><vczbe>"
   [(set (match_operand:<V_INT_EQUIV> 0 "register_operand" "=w")
 	(plus:<V_INT_EQUIV>
 	  (eq:<V_INT_EQUIV>
@@ -8023,6 +8033,22 @@
   [(set_attr "type" "neon_tst<q>")]
 )
 
+;; One can also get a cmtsts by having to combine a
+;; neg (ne x 0) in which case you rewrite it to
+;; a comparison against itself
+
+(define_insn "*aarch64_cmtst_same_<mode><vczle><vczbe>"
+  [(set (match_operand:<V_INT_EQUIV> 0 "register_operand" "=w")
+	(neg:<V_INT_EQUIV>
+	  (ne:<V_INT_EQUIV>
+	    (match_operand:VDQ_I 1 "register_operand" "w")
+	    (match_operand:VDQ_I 2 "aarch64_simd_imm_zero"))))
+  ]
+  "TARGET_SIMD"
+  "cmtst\t%<v>0<Vmtype>, %<v>1<Vmtype>, %<v>1<Vmtype>"
+  [(set_attr "type" "neon_tst<q>")]
+)
+
 ;; One can also get a cmtsts by having to combine a
 ;; not (neq (eq x 0)) in which case you rewrite it to
 ;; a comparison against itself