Suboptimal code generated for ?: as a condition

[Marcin 'Qrczak' Kowalczyk]

There is a missing opportunity for optimization.

int f(void);
void test(int x) {
   if (x & 1 ? x == 0 : x > 0) f();
}

This is gcc-4.1.0-0.20051206 with some patches by PLD Linux
Distribution. gcc -S -O2 -fomit-frame-pointer generates the
following code:

test:
        movl    4(%esp), %eax
        testb   $1, %al
        je      .L2
        testl   %eax, %eax
        sete    %al
        testb   %al, %al
        jne     .L9
.L7:
        rep ; ret
        .p2align 4,,7
.L2:
        testl   %eax, %eax
        setg    %al
        testb   %al, %al
        je      .L7
.L9:
        jmp     f

It makes little sense to materialize the boolean result of the
condition in %al, and then to test %al for 0. I would expect
direct conditional jumps to branches of the outer if.

-- 
   __("<         Marcin Kowalczyk
   \__/       qrczak@knm.org.pl
    ^^     http://qrnik.knm.org.pl/~qrczak/