https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88085
--- Comment #21 from rguenther at suse dot de <rguenther at suse dot de> --- On Thu, 2 Sep 2021, petro.karashchenko at gmail dot com wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88085 > > --- Comment #20 from Petro Karashchenko <petro.karashchenko at gmail dot com> > --- > I just checked next case > > typedef int tolerant_int __attribute__((aligned(1))); > tolerant_int var; > > int foo(void) > { > return var; > } > ---------------------------------- > arm-none-eabi-gcc -save-temps -Wall -Wextra -c -mcpu=arm7tdmi -mthumb test.c > -O0 > ---------------------------------- > .cpu arm7tdmi > .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, 6 > .eabi_attribute 34, 0 > .eabi_attribute 18, 4 > .file "test.c" > .text > .comm var,4,1 > .align 1 > .global foo > .arch armv4t > .syntax unified > .code 16 > .thumb_func > .fpu softvfp > .type foo, %function > foo: > @ Function supports interworking. > @ args = 0, pretend = 0, frame = 0 > @ frame_needed = 1, uses_anonymous_args = 0 > push {r7, lr} > add r7, sp, #0 > ldr r3, .L3 > ldr r3, [r3] > movs r0, r3 > mov sp, r7 > @ sp needed > pop {r7} > pop {r1} > bx r1 > .L4: > .align 2 > .L3: > .word var > .size foo, .-foo > .ident "GCC: (GNU Tools for Arm Embedded Processors 9-2019-q4-major) > 9.2.1 20191025 (release) [ARM/arm-9-branch revision 277599]" > --------------------------------- > > So seems the alignment decrease does not work on types. It works on trunk. There were bugs fixed for arm "recently" (your 9.2.1 is nearly two years old).
