https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113715
Bug ID: 113715 Summary: RISC-V: If the Zcmp is enabled, the a0 register operates abnormally when the program returns Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: mumuxi_ll at outlook dot com Target Milestone: --- When compiling the following test.c code with the options -march=rv32ima_zca_zcb_zcmp_zcmt -mabi=ilp32 -Os, a bug appears when gcc enables zcmp. In the disassembly dump.txt, it can be observed that when executing the bne instruction in test_err, a0 is not set to 0 as the function return value. Source code: void test_1(int onoff) { for (volatile int i = 0; i < 100; i ++) { } } int test_err(void *param, int mode, int *saveAddr) { if (mode == 2) { test_1(1); } return 0; } int main() { int ret = test_err((void *)0x123456, 3, (int *)0x123456); for (volatile int i = ret; i < 100; i ++) { ret = i * i; } return ret; } GCC ASM: test_1: addi sp,sp,-16 sw zero,12(sp) li a4,99 .L2: lw a5,12(sp) ble a5,a4,.L3 addi sp,sp,16 jr ra .L3: lw a5,12(sp) addi a5,a5,1 sw a5,12(sp) j .L2 test_err: li a5,2 bne a1,a5,.L8 li a0,1 cm.push {ra}, -16 call test_1 cm.popretz {ra}, 16 .L8: ret main: addi sp,sp,-16 sw zero,12(sp) li a0,0 li a3,99 .L12: lw a5,12(sp) ble a5,a3,.L13 addi sp,sp,16 jr ra .L13: lw a0,12(sp) lw a4,12(sp) mul a0,a0,a4 lw a4,12(sp) addi a4,a4,1 sw a4,12(sp) j .L12