diff mbox

[RFA,i386] : Warn for 64-bit values in general-reg asm operands and error out for 8-bit values in invalid GR asm operand

Message ID CAFULd4ZqXrFKb6mgfhvKW_OM8mvaYiv4MXaASQaKCugSY_kv9Q@mail.gmail.com
State New
Headers show

Commit Message

Uros Bizjak March 1, 2017, 10:41 a.m. UTC 
On Wed, Mar 1, 2017 at 10:00 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
> On Wed, Mar 1, 2017 at 9:48 AM, Jakub Jelinek <jakub@redhat.com> wrote:
>> On Wed, Mar 01, 2017 at 09:34:53AM +0100, Uros Bizjak wrote:
>>> Some more thoughts on 64-bit reg on 32-bit targets warning.
>>>
>>> Actually, we never *print* register name for instruction that use "A"
>>> constraint, since %eax/%edx is always implicit  The warning does not
>>> deal with constraints, so unless we want to output DImode register
>>> name, there is no warning.
>>
>> Ah, indeed, we don't have a modifier that would print the high register
>> of a register pair (i.e. essentially print REGNO (x) + 1 instead of REGNO
>> (x)), guess that might be useful not just for 64-bit GPR operands in 32-bit
>> code, but also 128-bit GPR operands in 64-bit code.
>
> The issue here is that (modulo ax/dx with "A" constraint) we don't
> guarantee double-register sequence order, so any change in register
> allocation order would break any assumptions. For implicit ax/dx, user
> should explicitly use register name (e.g. DImode operand in "rdtscp;
> mov %0, mem" asm should be corrected to use %%eax instead of %0).
>
> And, yes - we should add similar warning for 128-bit GPRs. The only
> way to use register pair with  width > machine_mode is with implicit
> operands or with explicit regnames.

Something like the following patch I'm testing:

--cut here--
--cut here--

Uros.
diff mbox

Patch

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 2b11aa1..943b2a0 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -17646,13 +17646,16 @@  print_reg (rtx x, int code, FILE *file)

   switch (msize)
     {
+    case 16:
+    case 12:
     case 8:
+      if (GENERAL_REGNO_P (regno) && msize > GET_MODE_SIZE (word_mode))
+       warning (0, "unsupported size for integer register");
+      /* FALLTHRU */
     case 4:
       if (LEGACY_INT_REGNO_P (regno))
        putc (msize == 8 && TARGET_64BIT ? 'r' : 'e', file);
       /* FALLTHRU */
-    case 16:
-    case 12:
     case 2:
     normal:
       reg = hi_reg_name[regno];