[Bug target/58259] ARM, PowerPC: Atomic flag test and set generates NULL pointer read and write

[sebastian.huber@embedded-brains.de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58259

Sebastian Huber <sebastian.huber@embedded-brains.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|powerpc-eabi                |powerpc-eabi, arm-eabi
            Summary|PowerPC: Atomic flag test   |ARM, PowerPC: Atomic flag
                   |and set generates NULL      |test and set generates NULL
                   |pointer read and write      |pointer read and write

--- Comment #1 from Sebastian Huber <sebastian.huber@embedded-brains.de> ---
Sorry, also the ARMv7 has the NULL pointer read and write problem:

arm-eabi-gcc -march=armv7-a -std=c11 -Wall -Wextra -O2 -S test.c && cat test.s
        .arch armv7-a
        .fpu softvfp
        .eabi_attribute 20, 1
        .eabi_attribute 21, 1
        .eabi_attribute 23, 3
        .eabi_attribute 24, 1
        .eabi_attribute 25, 1
        .eabi_attribute 26, 1
        .eabi_attribute 30, 2
        .eabi_attribute 34, 1
        .eabi_attribute 18, 4
        .file   "test.c"
        .text
        .align  2
        .global test_and_set
        .type   test_and_set, %function
test_and_set:
        @ args = 0, pretend = 0, frame = 0
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
        mov     r3, #0
        mov     r1, #1
        ldrb    r2, [r3]        @ zero_extendqisi2 <-- NULL POINTER READ
.L2:
        ldrexb  r3, [r0]
        cmp     r3, r2
        bne     .L3
        strexb  ip, r1, [r0]
        cmp     ip, #0
        bne     .L2
.L3:
        mov     r2, #0
        dmb     sy
        moveq   r0, #1
        strb    r3, [r2] <-- NULL POINTER WRITE
        movne   r0, r2
        bx      lr
        .size   test_and_set, .-test_and_set
        .ident  "GCC: (GNU) 4.9.0 20130828 (experimental) [master revision
022fc2d:bffd767:fd457cef14f3bc6673e90a2de80005feea743ab7]"