[llvm-bugs] [Bug 160612] x86 optimization: logical AND and OR in if-conditionals can turn to multiple branch instructions

[LLVM Bugs via llvm-bugs]

Issue	160612
Summary	x86 optimization: logical AND and OR in if-conditionals can turn to multiple branch instructions
Labels	new issue
Assignees
Reporter	Explorer09

    ```c
extern void subroutine_foo(void);
extern void subroutine_bar(void);
void func_a(int x, int y) {
    if (x == 0 || y == 0)
        subroutine_foo();
    else
 subroutine_bar();
}
void func_b(int x, int y) {
    if (x == 0)
 subroutine_foo();
    else if (y == 0)
        subroutine_foo();
 else
        subroutine_bar();
}
```

x86-64 clang-trunk-20250924 with `-Os` option produces:

```assembly
func_a:
        testl   %edi, %edi
 setne   %al
        testl   %esi, %esi
        setne   %cl
 testb   %cl, %al
        jne     subroutine_bar@PLT
        jmp subroutine_foo@PLT
func_b:
        testl   %edi, %edi
        je subroutine_foo@PLT
        testl   %esi, %esi
        je subroutine_foo@PLT
        jmp subroutine_bar@PLT
```

https://godbolt.org/z/ns1YxeKr5

Clang misses that there's no need to make temporary boolean variables for the conditional. It can use multiple branch instructions instead.

This issue looks x86 specific. Clang for AArch64 target generates optimal code.

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