[PATCH]AArch64: force operand to fresh register to avoid subreg issues [PR118892]

[Tamar Christina]

Hi All,

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 sugreg
relationship.

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

Bootstrapped Regtested on aarch64-none-linux-gnu and no issues.

Ok for master?

Thanks,
Tamar

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 
cfe730f3732ce45c914b30a908851a4a7dd77c0f..62be9713cf417922b3c06e38f12f401872751fa2
 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -7479,8 +7479,8 @@ (define_expand "copysign<GPF:mode>3"
       && real_isneg (CONST_DOUBLE_REAL_VALUE (op2_elt)))
     {
       emit_insn (gen_ior<vq_int_equiv>3 (
-       lowpart_subreg (<VQ_INT_EQUIV>mode, operands[0], <MODE>mode),
-       lowpart_subreg (<VQ_INT_EQUIV>mode, operands[1], <MODE>mode),
+       force_lowpart_subreg (<VQ_INT_EQUIV>mode, operands[0], <MODE>mode),
+       force_lowpart_subreg (<VQ_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 
0000000000000000000000000000000000000000..adfa30dc3e2db895af4f2057bdd1011fdb7d4537
--- /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]);
+}


-- 

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index cfe730f3732ce45c914b30a908851a4a7dd77c0f..62be9713cf417922b3c06e38f12f401872751fa2 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -7479,8 +7479,8 @@ (define_expand "copysign<GPF:mode>3"
       && real_isneg (CONST_DOUBLE_REAL_VALUE (op2_elt)))
     {
       emit_insn (gen_ior<vq_int_equiv>3 (
-	lowpart_subreg (<VQ_INT_EQUIV>mode, operands[0], <MODE>mode),
-	lowpart_subreg (<VQ_INT_EQUIV>mode, operands[1], <MODE>mode),
+	force_lowpart_subreg (<VQ_INT_EQUIV>mode, operands[0], <MODE>mode),
+	force_lowpart_subreg (<VQ_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 0000000000000000000000000000000000000000..adfa30dc3e2db895af4f2057bdd1011fdb7d4537
--- /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]);
+}