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tools/nolibc: x86-64: Use mov $60,%eax instead of mov $60,%rax

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Note that mov to 32-bit register will zero extend to 64-bit register.
Thus `mov $60,%eax` has the same effect with `mov $60,%rax`. Use the
shorter opcode to achieve the same thing.
```
  b8 3c 00 00 00       	mov    $60,%eax (5 bytes) [1]
  48 c7 c0 3c 00 00 00 	mov    $60,%rax (7 bytes) [2]
```
Currently, we use [2]. Change it to [1] for shorter code.

Signed-off-by: Ammar Faizi <ammar.faizi@students.amikom.ac.id>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Ammar Faizi 2021-10-24 19:43:22 +02:00 committed by Paul E. McKenney
parent bf91666959
commit 7bdc0e7a39
1 changed files with 1 additions and 1 deletions
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2
tools/include/nolibc/nolibc.h
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@ -420,7 +420,7 @@ asm(".section .text\n"
"and $-16, %rsp\n" // x86 ABI : esp must be 16-byte aligned before call
"call main\n" // main() returns the status code, we'll exit with it.
"mov %eax, %edi\n" // retrieve exit code (32 bit)
"mov $60, %rax\n" // NR_exit == 60
"mov $60, %eax\n" // NR_exit == 60
"syscall\n" // really exit
"hlt\n" // ensure it does not return
"");