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Subject'Re: [PATCH] drivers/android: remove redundant ret variable'
Date
I found that there are indeed some optimizations
after removing the redundancy.

For example:

int foo(int a, int b)
{
int ret;
ret = a>b ? a: b;
return ret;
}
int main()
{
int val;
val = foo(7,2);
return 0;
}

and

int foo(int a, int b)
{
return a>b ? a: b;
}
int main()
{
int val;
val = foo(7,2);
return 0;
}

The corresponding disassembly code is as follows:

1129: f3 0f 1e fa endbr64
112d: 55 push %rbp
112e: 48 89 e5 mov %rsp,%rbp
1131: 89 7d fc mov %edi,-0x4(%rbp)
1134: 89 75 f8 mov %esi,-0x8(%rbp)
1137: 8b 45 fc mov -0x4(%rbp),%eax
113a: 39 45 f8 cmp %eax,-0x8(%rbp)
113d: 0f 4d 45 f8 cmovge -0x8(%rbp),%eax
1141: 5d pop %rbp
1142: c3 retq

and

1129: f3 0f 1e fa endbr64
112d: 55 push %rbp
112e: 48 89 e5 mov %rsp,%rbp
1131: 89 7d ec mov %edi,-0x14(%rbp)
1134: 89 75 e8 mov %esi,-0x18(%rbp)
1137: 8b 45 ec mov -0x14(%rbp),%eax
113a: 39 45 e8 cmp %eax,-0x18(%rbp)
113d: 0f 4d 45 e8 cmovge -0x18(%rbp),%eax
1141: 89 45 fc mov %eax,-0x4(%rbp)
1144: 8b 45 fc mov -0x4(%rbp),%eax
1147: 5d pop %rbp
1148: c3 retq

After removing the redundancy, the compiler does
have some optimizations

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