aarch64: PR target/95526: Fix gimplification of varargs

[Alex Coplan]

This patch fixes a latent bug exposed by
eb72dc663e9070b281be83a80f6f838a3a878822 in the aarch64 backend that was
causing wrong codegen and several testsuite failures. See the discussion
on the bug for details.

Bootstrapped and regtested on aarch64-linux-gnu. Cleaned up several failing
tests and no new fails introduced:

+PASS: gcc.dg/compat/scalar-by-value-3 c_compat_x_tst.o-c_compat_y_tst.o execute
+PASS: gcc.dg/compat/scalar-by-value-4 c_compat_x_tst.o-c_compat_y_tst.o execute
+PASS: gcc.dg/compat/scalar-by-value-5 c_compat_x_tst.o-c_compat_y_tst.o execute
+PASS: gcc.dg/compat/scalar-by-value-6 c_compat_x_tst.o-c_compat_y_tst.o execute
+PASS: gcc.dg/compat/scalar-return-3 c_compat_x_tst.o-c_compat_y_tst.o execute
+PASS: gcc.dg/compat/scalar-return-4 c_compat_x_tst.o-c_compat_y_tst.o execute
+PASS: gcc.dg/complex-1.c execution test
+PASS: gcc.target/aarch64/aapcs64/va_arg-7.c execution,  -O0
+PASS: gcc.target/aarch64/aapcs64/va_arg-7.c execution,  -O1
+PASS: gcc.target/aarch64/aapcs64/va_arg-7.c execution,  -O2
+PASS: gcc.target/aarch64/aapcs64/va_arg-7.c execution,  -O3 -g
+PASS: gcc.target/aarch64/aapcs64/va_arg-7.c execution,  -Og -g
+PASS: gcc.target/aarch64/aapcs64/va_arg-7.c execution,  -Os

Pre-approved on bugzilla: committing to master.

Thanks,
Alex

---

2020-06-04  Richard Biener  <rguenther@suse.de>

gcc/ChangeLog:

        * config/aarch64/aarch64.c (aarch64_gimplify_va_arg_expr):
          Ensure that tmp_ha is marked TREE_ADDRESSABLE.

---

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 6352d4f..97da607 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -16370,6 +16370,7 @@ aarch64_gimplify_va_arg_expr (tree valist, tree type, gimple_seq *pre_p,
 	}
 
       /* *(field_ptr_t)&ha = *((field_ptr_t)vr_saved_area  */
+      TREE_ADDRESSABLE (tmp_ha) = 1;
       tmp_ha = build1 (ADDR_EXPR, field_ptr_t, tmp_ha);
       addr = t;
       t = fold_convert (field_ptr_t, addr);