On 17/11/15 12:00, Charles Baylis wrote:
> On 16 November 2015 at 22:24, Kugan <[email protected]> wrote:
>
>> Please note that we have a sibcall from "broken" to "indirect".
>>
>> "direct" is variadic function so it is conforming to AAPCS base standard.
>>
>> "broken" is a non-variadic function and will return the value in
>> floating point register for TARGET_HARD_FLOAT. Thus we should not be
>> doing sibcall here.
>>
>> Attached patch fixes this. Bootstrap and regression testing is ongoing.
>> Is this OK if no issues with the testing?
>
> Hi Kugan,
>
> It looks like this patch should work, but I think this is an overly
> conservative fix, as it prevents all sibcalls for hardfloat targets.
> It would be better if only variadic sibcalls were prevented on
> hardfloat. You can check for variadic calls by checking the
> function_type in the call expression (exp) using stdarg_p().
>
> As an example to show how to test for variadic function calls, this is
> how to test it in gdb:
>
> (gdb) b arm_function_ok_for_sibcall
> Breakpoint 1 at 0xdae59c: file
> /home/cbaylis/srcarea/gcc/gcc-git/gcc/config/arm/arm.c, line 6634.
> (gdb) r
> <snip>...
> Breakpoint 1, arm_function_ok_for_sibcall (decl=0x0, exp=0x7ffff6104ce8)
> at /home/cbaylis/srcarea/gcc/gcc-git/gcc/config/arm/arm.c:6634
> 6634 if (cfun->machine->sibcall_blocked)
> (gdb) print debug_tree(exp)
> <call_expr 0x7ffff6104ce8
> type <real_type 0x7ffff62835e8 double sizes-gimplified DF
> size <integer_cst 0x7ffff626cf18 constant 64>
> unit size <integer_cst 0x7ffff626cf30 constant 8>
> align 64 symtab 0 alias set -1 canonical type 0x7ffff62835e8
> precision 64
> pointer_to_this <pointer_type 0x7ffff62837e0>>
> side-effects addressable
> fn <ssa_name 0x7ffff6275708
> type <pointer_type 0x7ffff60e9540 type <function_type 0x7ffff60e9348>
> <snip>...
> (gdb) print stdarg_p((tree)0x7ffff60e9348) <--- from function_type ^^^^^
> $2 = true
>
How about:
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index a379121..2376d66 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -6681,6 +6681,13 @@ arm_function_ok_for_sibcall (tree decl, tree exp)
register. */
rtx a, b;
+ /* If it is an indirect function pointer, get the function type. */
+ if (!decl
+ && POINTER_TYPE_P (TREE_TYPE (CALL_EXPR_FN (exp)))
+ && (TREE_CODE (TREE_TYPE (TREE_TYPE (CALL_EXPR_FN (exp))))
+ == FUNCTION_TYPE))
+ decl = TREE_TYPE (TREE_TYPE (CALL_EXPR_FN (exp)));
+
a = arm_function_value (TREE_TYPE (exp), decl, false);
b = arm_function_value (TREE_TYPE (DECL_RESULT (cfun->decl)),
cfun->decl, false);
Thanks,
Kugan
