Re: Computer architects leaving Intel...

On 31.08.24 13:26, Thomas Koenig wrote:

So, sorry for the too-quick examples earlier...
 What about
 int foo (int a)
{
   return a + 1;
}
 or
 int foo(int *a)
{
   return *a;
}
 Both can exhibit undefined behavior, and for both it
is impossible for the compiler to tell at compile-time.

So the compiler should just compile both functions (gcc 12.2.0 with -O3 does):
$ gcc -Wall -Wextra -Wpedantic -O3 -xc -std=gnu11 -c - -o foo.o
int foo(int a)
{
     return a + 1;
}
int bar(int *a)
{
     return *a;
}
^D
$ objdump -d foo.o
foo.o:     file format elf64-x86-64
Disassembly of section .text:
0000000000000000 <foo>:
    0:   8d 47 01                lea    0x1(%rdi),%eax
    3:   c3                      ret
    4:   66 66 2e 0f 1f 84 00    data16 cs nopw 0x0(%rax,%rax,1)
    b:   00 00 00 00
    f:   90                      nop
0000000000000010 <bar>:
   10:   8b 07                   mov    (%rdi),%eax
   12:   c3                      ret
All as expected.
What I don't want is that the compiler makes assumptions, concludes UB, feels entitled to compile whatever it wants and deliver rubbish without telling about it.
--
Bernd Linsel