[PING][PATCH 1/3] RISC-V: add a new parameter in riscv_first_stack_step.

["Fei Gao" <gaofei@eswincomputing.com>]

Gentle ping.

The patch I previously submitted:
| Date: Wed, 30 Nov 2022 00:38:08 -0800
| Subject: [PATCH] RISC-V: optimize stack manipulation in save-restore
| Message-ID: <gaofei@eswincomputing.com>

I split the patches as per Palmer's review comment.

BR
Fei

>frame->total_size to remaining_size conversion is done as an independent patch without
>functionality change as per review comment.
>
>gcc/ChangeLog:
>
>        * config/riscv/riscv.cc (riscv_first_stack_step): add a new function parameter remaining_size.
>        (riscv_compute_frame_info): adapt new riscv_first_stack_step interface.
>        (riscv_expand_prologue): likewise.
>        (riscv_expand_epilogue): likewise.
>---
> gcc/config/riscv/riscv.cc | 48 +++++++++++++++++++--------------------
> 1 file changed, 24 insertions(+), 24 deletions(-)
>
>diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
>index 05bdba5ab4d..f0bbcd6d6be 100644
>--- a/gcc/config/riscv/riscv.cc
>+++ b/gcc/config/riscv/riscv.cc
>@@ -4634,7 +4634,7 @@ riscv_save_libcall_count (unsigned mask)
>    They decrease stack_pointer_rtx but leave frame_pointer_rtx and
>    hard_frame_pointer_rtx unchanged.  */
>
>-static HOST_WIDE_INT riscv_first_stack_step (struct riscv_frame_info *frame);
>+static HOST_WIDE_INT riscv_first_stack_step (struct riscv_frame_info *frame, poly_int64 remaining_size);
>
> /* Handle stack align for poly_int.  */
> static poly_int64
>@@ -4663,7 +4663,7 @@ riscv_compute_frame_info (void)
>      save/restore t0.  We check for this before clearing the frame struct.  */
>   if (cfun->machine->interrupt_handler_p)
>     {
>-      HOST_WIDE_INT step1 = riscv_first_stack_step (frame);
>+      HOST_WIDE_INT step1 = riscv_first_stack_step (frame, frame->total_size);
>       if (! POLY_SMALL_OPERAND_P ((frame->total_size - step1)))
> interrupt_save_prologue_temp = true;
>     }
>@@ -4913,45 +4913,45 @@ riscv_restore_reg (rtx reg, rtx mem)
>    without adding extra instructions.  */
>
> static HOST_WIDE_INT
>-riscv_first_stack_step (struct riscv_frame_info *frame)
>+riscv_first_stack_step (struct riscv_frame_info *frame, poly_int64 remaining_size)
> {
>-  HOST_WIDE_INT frame_total_constant_size;
>-  if (!frame->total_size.is_constant ())
>-    frame_total_constant_size
>-      = riscv_stack_align (frame->total_size.coeffs[0])
>-	- riscv_stack_align (frame->total_size.coeffs[1]);
>+  HOST_WIDE_INT remaining_const_size;
>+  if (!remaining_size.is_constant ())
>+    remaining_const_size
>+      = riscv_stack_align (remaining_size.coeffs[0])
>+        - riscv_stack_align (remaining_size.coeffs[1]);
>   else
>-    frame_total_constant_size = frame->total_size.to_constant ();
>+    remaining_const_size = remaining_size.to_constant ();
>
>-  if (SMALL_OPERAND (frame_total_constant_size))
>-    return frame_total_constant_size;
>+  if (SMALL_OPERAND (remaining_const_size))
>+    return remaining_const_size;
>
>   HOST_WIDE_INT min_first_step =
>-    RISCV_STACK_ALIGN ((frame->total_size - frame->frame_pointer_offset).to_constant());
>+    riscv_stack_align ((remaining_size - frame->frame_pointer_offset).to_constant());
>   HOST_WIDE_INT max_first_step = IMM_REACH / 2 - PREFERRED_STACK_BOUNDARY / 8;
>-  HOST_WIDE_INT min_second_step = frame_total_constant_size - max_first_step;
>+  HOST_WIDE_INT min_second_step = remaining_const_size - max_first_step;
>   gcc_assert (min_first_step <= max_first_step);
>
>   /* As an optimization, use the least-significant bits of the total frame
>      size, so that the second adjustment step is just LUI + ADD.  */
>   if (!SMALL_OPERAND (min_second_step)
>-      && frame_total_constant_size % IMM_REACH < IMM_REACH / 2
>-      && frame_total_constant_size % IMM_REACH >= min_first_step)
>-    return frame_total_constant_size % IMM_REACH;
>+      && remaining_const_size % IMM_REACH < IMM_REACH / 2
>+      && remaining_const_size % IMM_REACH >= min_first_step)
>+    return remaining_const_size % IMM_REACH;
>
>   if (TARGET_RVC)
>     {
>       /* If we need two subtracts, and one is small enough to allow compressed
>-	loads and stores, then put that one first.  */
>+         loads and stores, then put that one first.  */
>       if (IN_RANGE (min_second_step, 0,
>-	    (TARGET_64BIT ? SDSP_REACH : SWSP_REACH)))
>-	return MAX (min_second_step, min_first_step);
>+                    (TARGET_64BIT ? SDSP_REACH : SWSP_REACH)))
>+       return MAX (min_second_step, min_first_step);
>
>       /* If we need LUI + ADDI + ADD for the second adjustment step, then start
>-	with the minimum first step, so that we can get compressed loads and
>-	stores.  */
>+         with the minimum first step, so that we can get compressed loads and
>+         stores.  */
>       else if (!SMALL_OPERAND (min_second_step))
>-	return min_first_step;
>+       return min_first_step;
>     }
>
>   return max_first_step;
>@@ -5037,7 +5037,7 @@ riscv_expand_prologue (void)
>   /* Save the registers.  */
>   if ((frame->mask | frame->fmask) != 0)
>     {
>-      HOST_WIDE_INT step1 = riscv_first_stack_step (frame);
>+      HOST_WIDE_INT step1 = riscv_first_stack_step (frame, frame->total_size);
>       if (size.is_constant ())
> step1 = MIN (size.to_constant(), step1);
>
>@@ -5216,7 +5216,7 @@ riscv_expand_epilogue (int style)
>      possible in the second step without going out of range.  */
>   if ((frame->mask | frame->fmask) != 0)
>     {
>-      step2 = riscv_first_stack_step (frame);
>+      step2 = riscv_first_stack_step (frame, frame->total_size);
>       step1 -= step2;
>     }
>
>--
>2.17.1