https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117310
Bug ID: 117310
Summary: Unnecessary zero-extension for tailcall
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: hjl.tools at gmail dot com
CC: crazylht at gmail dot com
Target Milestone: ---
[hjl@gnu-tgl-3 tailcall-1]$ cat x.c
extern int baz (char c1);
int
foo (char c1)
{
return baz (c1);
}
[hjl@gnu-tgl-3 tailcall-1]$ make CC=gcc
gcc -O2 -S x.c
[hjl@gnu-tgl-3 tailcall-1]$ cat x.s
.file "x.c"
.text
.p2align 4
.globl foo
.type foo, @function
foo:
.LFB0:
.cfi_startproc
movsbl %dil, %edi <<<< This isn't needed.
jmp baz
.cfi_endproc
.LFE0:
.size foo, .-foo
.ident "GCC: (GNU) 14.2.1 20240912 (Red Hat 14.2.1-3)"
.section .note.GNU-stack,"",@progbits
[hjl@gnu-tgl-3 tailcall-1]$
movsbl isn't needed regardless if baz is compiled by GCC nor non-GCC.
