[Bug c/22278] New: gcc -O2 discards cast to volatile

[olivier dot baudron at m4x dot org]

In the following testcase, a read memory access should be made.
However gcc -O2 optimizes away the code inside the test function.

--- test.c 
void test (char *addr) {
*((volatile char *) addr);
}
---

$ gcc -Wall -O2 -S test.c

--- test.s 
test.s:
.file   test.c
.text
.p2align 4,,15
.globl test
.type   test, @function
test:
pushl   %ebp
movl%esp, %ebp
popl%ebp
ret
.size   test, .-test
.ident  GCC: (GNU) 4.1.0 20050702 (experimental)
.section.note.GNU-stack,,@progbits
---

-- 
   Summary: gcc -O2 discards cast to volatile
   Product: gcc
   Version: 4.1.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P2
 Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: olivier dot baudron at m4x dot org
CC: gcc-bugs at gcc dot gnu dot org
  GCC host triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22278

[Bug c/22278] gcc -O2 discards cast to volatile

[olivier dot baudron at m4x dot org]

--- Additional Comments From olivier dot baudron at m4x dot org  2005-07-02 
16:59 ---
I am not sure this is the same problem.
Besides, the following code is *not* optimized away with -O2:

void test (volatile char *addr) {
*addr;
}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22278