https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78512
--- Comment #1 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
I run md5sum on the object files with and without -fno-printf-return-value.
Looking at a few files that differ they show a common pattern:
good vs bad diff:
@@ -312,7 +312,7 @@
movq $.LC1, %rsi
movq %rax, %rdi
call sprintf
- cltq
+ movl $2, %eax
ret
.size show_tx_maxrate, .-show_tx_maxrate
.section .rodata.str1.1
@@ -338,8 +338,8 @@
movq $.LC3, %rsi
movq %rbp, %rdi
call sprintf
+ movl $1, %eax
popq %rbx
- cltq
popq %rbp
ret
.size show_trans_timeout, .-show_trans_timeout
@@ -749,7 +749,7 @@
movq $fmt_u64, %rsi
movq %rbp, %rdi
call sprintf
- cltq
+ movl $2, %eax
.L121:
movl $-256, %edx
etc.
Not sure if this a valid transformation or even the root cause of the issue.
