Currently in rv32e, stack allocation for GPR callee-saved registers is
always 12 bytes w/o save-restore. Actually, for the case without save-restore,
less stack memory can be reserved. This patch decouples stack allocation for
rv32e w/o save-restore and makes riscv_compute_frame_info more readable.
output of testcase rv32e_stack.c
before patch:
addi sp,sp,-16
sw ra,12(sp)
call getInt
sw a0,0(sp)
lw a0,0(sp)
call PrintInts
lw a5,0(sp)
mv a0,a5
lw ra,12(sp)
addi sp,sp,16
jr ra
after patch:
addi sp,sp,-8
sw ra,4(sp)
call getInt
sw a0,0(sp)
lw a0,0(sp)
call PrintInts
lw a5,0(sp)
mv a0,a5
lw ra,4(sp)
addi sp,sp,8
jr ra
gcc/ChangeLog:
* config/riscv/riscv.cc (riscv_avoid_save_libcall): helper function for
riscv_use_save_libcall.
(riscv_use_save_libcall): call riscv_avoid_save_libcall.
(riscv_compute_frame_info): restructure to decouple stack allocation
for rv32e w/o save-restore.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/rv32e_stack.c: New test.
---
gcc/config/riscv/riscv.cc | 58 ++++++++++++--------
gcc/testsuite/gcc.target/riscv/rv32e_stack.c | 14 +++++
2 files changed, 50 insertions(+), 22 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/riscv/rv32e_stack.c
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 5d2550871c7..8b32977e296 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -4772,12 +4772,27 @@ riscv_save_reg_p (unsigned int regno)
return false;
}
+/* Return TRUE if a libcall to save/restore GPRs should be
+ avoided. FALSE otherwise. */
+static bool
+riscv_avoid_save_libcall (void)
+{
+ if (!TARGET_SAVE_RESTORE
+ || crtl->calls_eh_return
+ || frame_pointer_needed
+ || cfun->machine->interrupt_handler_p
+ || cfun->machine->varargs_size != 0
+ || crtl->args.pretend_args_size != 0)
+ return true;
+
+ return false;
+}
+
/* Determine whether to call GPR save/restore routines. */
static bool
riscv_use_save_libcall (const struct riscv_frame_info *frame)
{
- if (!TARGET_SAVE_RESTORE || crtl->calls_eh_return || frame_pointer_needed
- || cfun->machine->interrupt_handler_p)
+ if (riscv_avoid_save_libcall ())
return false;
return frame->save_libcall_adjustment != 0;
@@ -4857,7 +4872,7 @@ riscv_compute_frame_info (void)
struct riscv_frame_info *frame;
poly_int64 offset;
bool interrupt_save_prologue_temp = false;
- unsigned int regno, i, num_x_saved = 0, num_f_saved = 0;
+ unsigned int regno, i, num_x_saved = 0, num_f_saved = 0, x_save_size = 0;
frame = &cfun->machine->frame;
@@ -4895,24 +4910,14 @@ riscv_compute_frame_info (void)
frame->fmask |= 1 << (regno - FP_REG_FIRST), num_f_saved++;
}
- /* At the bottom of the frame are any outgoing stack arguments. */
- offset = riscv_stack_align (crtl->outgoing_args_size);
- /* Next are local stack variables. */
- offset += riscv_stack_align (get_frame_size ());
- /* The virtual frame pointer points above the local variables. */
- frame->frame_pointer_offset = offset;
- /* Next are the callee-saved FPRs. */
- if (frame->fmask)
- offset += riscv_stack_align (num_f_saved * UNITS_PER_FP_REG);
- frame->fp_sp_offset = offset - UNITS_PER_FP_REG;
- /* Next are the callee-saved GPRs. */
if (frame->mask)
{
- unsigned x_save_size = riscv_stack_align (num_x_saved * UNITS_PER_WORD);
+ x_save_size = riscv_stack_align (num_x_saved * UNITS_PER_WORD);
unsigned num_save_restore = 1 + riscv_save_libcall_count (frame->mask);
/* Only use save/restore routines if they don't alter the stack size. */
- if (riscv_stack_align (num_save_restore * UNITS_PER_WORD) == x_save_size)
+ if (riscv_stack_align (num_save_restore * UNITS_PER_WORD) == x_save_size
+ && !riscv_avoid_save_libcall ())
{
/* Libcall saves/restores 3 registers at once, so we need to
allocate 12 bytes for callee-saved register. */
@@ -4921,9 +4926,21 @@ riscv_compute_frame_info (void)
frame->save_libcall_adjustment = x_save_size;
}
-
- offset += x_save_size;
}
+
+ /* At the bottom of the frame are any outgoing stack arguments. */
+ offset = riscv_stack_align (crtl->outgoing_args_size);
+ /* Next are local stack variables. */
+ offset += riscv_stack_align (get_frame_size ());
+ /* The virtual frame pointer points above the local variables. */
+ frame->frame_pointer_offset = offset;
+ /* Next are the callee-saved FPRs. */
+ if (frame->fmask)
+ offset += riscv_stack_align (num_f_saved * UNITS_PER_FP_REG);
+ frame->fp_sp_offset = offset - UNITS_PER_FP_REG;
+ /* Next are the callee-saved GPRs. */
+ if (frame->mask)
+ offset += x_save_size;
frame->gp_sp_offset = offset - UNITS_PER_WORD;
/* The hard frame pointer points above the callee-saved GPRs. */
frame->hard_frame_pointer_offset = offset;
@@ -4935,11 +4952,8 @@ riscv_compute_frame_info (void)
padding. */
frame->arg_pointer_offset = offset - crtl->args.pretend_args_size;
frame->total_size = offset;
- /* Next points the incoming stack pointer and any incoming arguments. */
- /* Only use save/restore routines when the GPRs are atop the frame. */
- if (known_ne (frame->hard_frame_pointer_offset, frame->total_size))
- frame->save_libcall_adjustment = 0;
+ /* Next points the incoming stack pointer and any incoming arguments. */
}
/* Make sure that we're not trying to eliminate to the wrong hard frame
diff --git a/gcc/testsuite/gcc.target/riscv/rv32e_stack.c
b/gcc/testsuite/gcc.target/riscv/rv32e_stack.c
new file mode 100644
index 00000000000..cec90ede4b5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rv32e_stack.c
@@ -0,0 +1,14 @@
+/* { dg-do compile} */
+/* { dg-options "-O0 -march=rv32e -mabi=ilp32e -fomit-frame-pointer" } */
+
+int getInt();
+void PrintInts(int);
+
+int callPrintInts()
+{
+ int i = getInt();
+ PrintInts(i);
+ return i;
+}
+
+/* { dg-final { scan-assembler-not "addi sp,sp,-16" } } */
--
2.17.1
