[gcc r13-2243] RISC-V: Suppress -Wclass-memaccess warning

[Kito Cheng <kito@gcc.gnu.org>]

https://gcc.gnu.org/g:7b9b6969a99725a171ee0ad4006cc39b0f7abf77

commit r13-2243-g7b9b6969a99725a171ee0ad4006cc39b0f7abf77
Author: Kito Cheng <kito.cheng@sifive.com>
Date:   Mon Aug 29 10:28:28 2022 +0800

    RISC-V: Suppress -Wclass-memaccess warning
    
    poly_int64 is non-trivial type, we need to clean up manully instead
    of memset to prevent this warning.
    
    ../../gcc/gcc/config/riscv/riscv.cc: In function 'void riscv_compute_frame_info()':
    ../../gcc/gcc/config/riscv/riscv.cc:4113:10: error: 'void* memset(void*, int, size_t)' clearing an object of non-trivial type 'struct riscv_frame_info'; use assignment or value-initialization instead [-Werror=class-memaccess]
     4113 |   memset (frame, 0, sizeof (*frame));
          |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
    ../../gcc/gcc/config/riscv/riscv.cc:101:17: note: 'struct riscv_frame_info' declared here
      101 | struct GTY(())  riscv_frame_info {
          |                 ^~~~~~~~~~~~~~~~
    cc1plus: all warnings being treated as errors
    
    gcc/ChangeLog:
    
            * config/riscv/riscv.cc (riscv_frame_info): Introduce `reset(void)`;
            (riscv_frame_info::reset(void)): New.
            (riscv_compute_frame_info): Use riscv_frame_info::reset instead
            of memset when clean frame.

Diff:
---
 gcc/config/riscv/riscv.cc | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 6341dc98daa..4d439e15392 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -123,6 +123,9 @@ struct GTY(())  riscv_frame_info {
 
   /* The offset of arg_pointer_rtx from the bottom of the frame.  */
   poly_int64 arg_pointer_offset;
+
+  /* Reset this struct, clean all field to zero.  */
+  void reset(void);
 };
 
 enum riscv_privilege_levels {
@@ -392,6 +395,23 @@ static const struct riscv_tune_info riscv_tune_info_table[] = {
   { "size", generic, &optimize_size_tune_info },
 };
 
+void riscv_frame_info::reset(void)
+{
+  total_size = 0;
+  mask = 0;
+  fmask = 0;
+  save_libcall_adjustment = 0;
+
+  gp_sp_offset = 0;
+  fp_sp_offset = 0;
+
+  frame_pointer_offset = 0;
+
+  hard_frame_pointer_offset = 0;
+
+  arg_pointer_offset = 0;
+}
+
 /* Implement TARGET_MIN_ARITHMETIC_PRECISION.  */
 
 static unsigned int
@@ -4179,7 +4199,7 @@ riscv_compute_frame_info (void)
 	interrupt_save_prologue_temp = true;
     }
 
-  memset (frame, 0, sizeof (*frame));
+  frame->reset();
 
   if (!cfun->machine->naked_p)
     {