https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117933

            Bug ID: 117933
           Summary: [lra][avr] Increased code size / stack usage with
                    -mlra
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gjl at gcc dot gnu.org
  Target Milestone: ---

Created attachment 59802
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=59802&action=edit
u32-to-string.c: C test case

$ avr-gcc-15 -c -o x-v0.o u32-to-string.c -save-temps=obj -mmcu=atmega128 -Os
$ avr-gcc-15 -c -o x-v1.o u32-to-string.c -save-temps=obj -mmcu=atmega128 -Os
-mlra
$ avr-size x-v0.o
   text    data     bss     dec     hex filename
    120       0       0     120      78 x-v0.o
$ avr-size x-v1.o
   text    data     bss     dec     hex filename
    138       0       0     138      8a x-v1.o

The prologue in either case is reading:

u32_to_string: ; with -mno-lra (x-v0.s)
        push r16
        push r17
        push r28
/* prologue: function */
/* frame size = 0 */
/* stack size = 3 */
.L__stack_usage = 3


u32_to_string: ; with -mlra (x-v1.s)
        push r12
        push r13
        push r14
        push r15
        push r17
        push r28
        push r29
/* prologue: function */
/* frame size = 0 */
/* stack size = 7 */
.L__stack_usage = 7

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