Hi Adhemerval,
On 06/10/16 22:54, Adhemerval Zanella wrote:
+ bool split_stack_arg_pointer_used = split_stack_arg_pointer_used_p ();
if (flag_stack_usage_info)
current_function_static_stack_size = frame_size;
@@ -3220,6 +3264,10 @@ aarch64_expand_prologue (void)
aarch64_emit_probe_stack_range (STACK_CHECK_PROTECT, frame_size);
}
+ /* Save split-stack argument pointer before stack adjustment. */
+ if (split_stack_arg_pointer_used)
+ emit_move_insn (gen_rtx_REG (Pmode, R10_REGNUM), stack_pointer_rtx);
+
aarch64_add_constant (Pmode, SP_REGNUM, IP0_REGNUM, -initial_adjust, true);
if (callee_adjust != 0)
@@ -3243,6 +3291,30 @@ aarch64_expand_prologue (void)
callee_adjust != 0 || frame_pointer_needed);
aarch64_add_constant (Pmode, SP_REGNUM, IP1_REGNUM, -final_adjust,
!frame_pointer_needed);
+
+ if (split_stack_arg_pointer_used_p ())
Redundant call? can use split_stack_arg_pointer_use"
+
+ /* Always emit two insns to calculate the requested stack, so the linker
+ can edit them when adjusting size for calling non-split-stack code. */
+ ninsn = aarch64_internal_mov_immediate (temp, GEN_INT (-frame_size), true,
+ Pmode);
+ gcc_assert (ninsn == 1 || ninsn == 2);
+ if (ninsn == 1)
+ emit_insn (gen_nop ());
If you expect the nop is kept together with the other
I am still seeing nop scheduled away from the addtition.
mov x10, -4144
add x10, sp, x10
nop
+
+#define BACKOFF 0x2000
The BACKOFF value is 0x2000 here while in morestack-c.c it is 0x1000, is
this deliberate?
+
+ # Calculate requested stack size.
+ sub x12, sp, x10
+ # Save parameters
+ stp x29, x30, [sp, -MORESTACK_FRAMESIZE]!
+ .cfi_def_cfa_offset MORESTACK_FRAMESIZE
+ .cfi_offset 29, -MORESTACK_FRAMESIZE
+ .cfi_offset 30, -MORESTACK_FRAMESIZE+8
+ add x29, sp, 0
+ .cfi_def_cfa_register 29
+ # Adjust the requested stack size for the frame pointer save.
+ add x12, x12, 16
+ stp x0, x1, [sp, 16]
+ stp x2, x3, [sp, 32]
+ add x12, x12, BACKOFF
+ stp x4, x5, [sp, 48]
+ stp x6, x7, [sp, 64]
+ stp x28, x12, [sp, 80]
+
+ # Setup on x28 the function initial frame pointer. Its value will
+ # copied to function argument pointer.
+ add x28, sp, MORESTACK_FRAMESIZE + 16
+
+ # void __morestack_block_signals (void)
+ bl __morestack_block_signals
+
+ # void *__generic_morestack (size_t *pframe_size,
+ # void *old_stack,
+ # size_t param_size)
+ # pframe_size: is the size of the required stack frame (the function
+ # amount of space remaining on the allocated stack).
s/pframe_size: is the size/pframe_size: points at the size/
+
+ # Set up for a call to the target function.
+ ldr x30, [x28, STACKFRAME_BASE + 8]
+ ldp x0, x1, [x28, STACKFRAME_BASE + 16]
+ ldp x2, x3, [x28, STACKFRAME_BASE + 32]
+ ldp x4, x5, [x28, STACKFRAME_BASE + 48]
+ ldp x6, x7, [x28, STACKFRAME_BASE + 64]
+ add x9, x30, 8
+ cmp x30, x9
We can remove this "cmp" by using "adds x9, x30, 8"?
I am thinkg "adds" will set "c" bit in conditional flag to zero, then
the bcs
check in function prologue will fail, thus the argument pointer
initialization
will always be executed if the execution flow is from __morestack.
bcs .L8
mov x10, x28
+ blr x9
+
+ stp x0, x1, [x28, STACKFRAME_BASE + 16]
+ stp x2, x3, [x28, STACKFRAME_BASE + 32]
+ stp x4, x5, [x28, STACKFRAME_BASE + 48]
+ stp x6, x7, [x28, STACKFRAME_BASE + 64]
+
