From: Tamar Christina <tamar.christina@arm.com>
Date: Mon, 28 Apr 2025 11:58:37 +0000 (+0100)
Subject: aarch64: force operand to fresh register to avoid subreg issues [PR118892]
X-Git-Tag: releases/gcc-14.3.0~110
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9ce381170ed40874230db05111f8837475634e4b;p=thirdparty%2Fgcc.git

aarch64: force operand to fresh register to avoid subreg issues [PR118892]

When the input is already a subreg and we try to make a paradoxical
subreg out of it for copysign this can fail if it violates the subreg
relationship.

Use force_lowpart_subreg instead of lowpart_subreg to then force the
results to a register instead of ICEing.

gcc/ChangeLog:

	PR target/118892
	* config/aarch64/aarch64.md (copysign<GPF:mode>3): Use
	force_lowpart_subreg instead of lowpart_subreg.

gcc/testsuite/ChangeLog:

	PR target/118892
	* gcc.target/aarch64/copysign-pr118892.c: New test.
---

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 95577b325ce..6a481059bf0 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -7210,7 +7210,7 @@
 
       emit_insn (gen_iorv2<v_int_equiv>3 (
 	lowpart_subreg (V2<V_INT_EQUIV>mode, operands[0], <MODE>mode),
-	lowpart_subreg (V2<V_INT_EQUIV>mode, operands[1], <MODE>mode),
+	force_lowpart_subreg (V2<V_INT_EQUIV>mode, operands[1], <MODE>mode),
 	v_bitmask));
       DONE;
     }
diff --git a/gcc/testsuite/gcc.target/aarch64/copysign-pr118892.c b/gcc/testsuite/gcc.target/aarch64/copysign-pr118892.c
new file mode 100644
index 00000000000..adfa30dc3e2
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/copysign-pr118892.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-Ofast" } */
+
+double l();
+double f()
+{
+  double t6[2] = {l(), l()};
+  double t7[2];
+  __builtin_memcpy(&t7, &t6, sizeof(t6));
+  return -__builtin_fabs(t7[1]);
+}