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SubjectRe: [PATCH] tools: Strong conversion of void type pointer could be removed

Hi Shuah, now I can't paste the test code, so I could write a demo and paste it:


#include <stdio.h>
#include <stdlib.h>

struct ucontext {
struct ucontext *uc_link;
unsigned long uc_flags;
sigset_t uc_sigmask;
struct ucontext *uc_mcontext;
typedef struct ucontext ucontext_t;

void sigsegv(void *ctx_void)
ucontext_t *ctx = (ucontext_t*)ctx_void;
ucontext_t *ctx2 = (int *)ctx_void;
ucontext_t *ctx3 = ctx_void;
printf("ctx:%p, ctx2:%p, ctx3:%p.\n", ctx, ctx2, ctx3);

int main() {
ucontext_t *test = malloc(sizeof(ucontext_t));
return 0;


The result is CTX: 0x563D96CE5010, CTX2:0x563D96CE5010, CTx3:0x563D96CE5010.
Now force ucontext_t and int pointers are the same as the addresses obtained without forced conversion.

Now I'll paste the assembly code for them:

|0x700 <sigsegv> push %rbp │
│0x701 <sigsegv+1> mov %rsp,%rbp │
│0x704 <sigsegv+4> sub $0x30,%rsp │
│0x708 <sigsegv+8> mov %rdi,-0x28(%rbp) │
│0x70c <sigsegv+12> mov -0x28(%rbp),%rax │
│0x710 <sigsegv+16> mov %rax,-0x8(%rbp) │
│0x714 <sigsegv+20> mov -0x28(%rbp),%rax │
│0x718 <sigsegv+24> mov %rax,-0x10(%rbp) │
│0x71c <sigsegv+28> mov -0x28(%rbp),%rax │
│0x720 <sigsegv+32> mov %rax,-0x18(%rbp) │
│0x724 <sigsegv+36> mov -0x18(%rbp),%rcx │
│0x728 <sigsegv+40> mov -0x10(%rbp),%rdx │
│0x72c <sigsegv+44> mov -0x8(%rbp),%rax │
│0x730 <sigsegv+48> mov %rax,%rsi │
│0x733 <sigsegv+51> lea 0xba(%rip),%rdi # 0x7f4 │
│0x73a <sigsegv+58> mov $0x0,%eax │
│0x73f <sigsegv+63> callq 0x5a0 <printf@plt> │
│0x744 <sigsegv+68> nop │
│0x745 <sigsegv+69> leaveq │
│0x746 <sigsegv+70> retq

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