https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110634
Bug ID: 110634
Summary: Incorrect RISC-V assembly with -fno-omit-frame-pointer
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: bjorn at kernel dot org
Target Milestone: ---
Is see inconsistencies when comparing -fno-omit-frame-pointer GCC and clang
builds.
$ cat foo.c
int foo(int a, int b) {
return a + b;
}
$ clang-17 --target=riscv64-linux-gnu -O3 -fno-omit-frame-pointer -c foo.c -o
foo.o && riscv64-linux-gnu-objdump -d foo.o
foo.o: file format elf64-littleriscv
Disassembly of section .text:
0000000000000000 <foo>:
0: 1141 add sp,sp,-16
2: e406 sd ra,8(sp)
4: e022 sd s0,0(sp)
6: 0800 add s0,sp,16
8: 9d2d addw a0,a0,a1
a: 60a2 ld ra,8(sp)
c: 6402 ld s0,0(sp)
e: 0141 add sp,sp,16
10: 8082 ret
Where GCC yields:
$ riscv64-linux-gnu-gcc -O3 -fno-omit-frame-pointer -c foo.c -o foo.o &&
riscv64-linux-gnu-objdump -d foo.o
foo.o: file format elf64-littleriscv
Disassembly of section .text:
0000000000000000 <foo>:
0: 1141 add sp,sp,-16
2: e422 sd s0,8(sp)
4: 0800 add s0,sp,16
6: 6422 ld s0,8(sp)
8: 9d2d addw a0,a0,a1
a: 0141 add sp,sp,16
c: 8082 ret
I would expect GCC to store "ra" similar to clang, but the spec is a bit vague
[1].
https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-cc.adoc#frame-pointer-convention
