https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110188
Bug ID: 110188
Summary: gcc for RISC-V stack aligned error
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: jzhgonha at 163 dot com
Target Milestone: ---
I use gcc(10.2.0) which is for RISC-V to compile a C language function,
according to disassembly language, stack just consumed 3word(12bytes), RISC-V
specification stipulate stack must aligned 16byte, but actual "addi sp,sp,-32"
show that stack occupy 32bytes, why not 16bytes?
I have tried different optimization levels, but all occupy 32bytes.
I also have tried another compiler which is called zcc, that occupy 16bytes.
C code main.c is following
int myadd(int a1, int a2, int a3, int a4, int a5, int a6, int a7, int a8, int
a9);
int main(void)
{
return myadd(1,2,3,4,5,6,7,8,9);
}
command line is following
riscv64-unknown-elf-gcc -c main.c -o main.o -march=rv32imac
-mpreferred-stack-boundary=4
riscv64-unknown-elf-objdump -d main.o > main.asm
diassembly main.asm is following
00000000 <main>:
0: 1101 addi sp,sp,-32
2: ce06 sw ra,28(sp)
4: cc22 sw s0,24(sp)
6: 1000 addi s0,sp,32
8: 47a5 li a5,9
a: c03e sw a5,0(sp)
c: 48a1 li a7,8
e: 481d li a6,7
10: 4799 li a5,6
12: 4715 li a4,5
14: 4691 li a3,4
16: 460d li a2,3
18: 4589 li a1,2
1a: 4505 li a0,1
1c: 00000097 auipc ra,0x0
20: 000080e7 jalr ra # 1c <main+0x1c>
24: 87aa mv a5,a0
26: 853e mv a0,a5
28: 40f2 lw ra,28(sp)
2a: 4462 lw s0,24(sp)
2c: 6105 addi sp,sp,32
2e: 8082 ret
