Source:
int g1,g2,g3;

int f1(int a, int b)
{
    a &= 1;
    
    if (a) return g1;
    return g2;
}

int f2(int a, int b)
{
    a &= 1;
    
    if (b)
        g3++;
    
    if (a) return g1;
    return g2;
}

Compiled with:
> gcc -O3 -fomit-frame-pointer -S and_flags.c

f1 is ok but f2 generates this:
_f2:
	andl	$1, %edi <-- #1
	testl	%esi, %esi
	je	L7
	movq	_g3@GOTPCREL(%rip), %rax
	incl	(%rax)
L7:
	testl	%edi, %edi <-- #2
	jne	L10
	movq	_g2@GOTPCREL(%rip), %rax
	movl	(%rax), %eax
	ret
	.align 4,0x90
L10:
	movq	_g1@GOTPCREL(%rip), %rax
	movl	(%rax), %eax
	ret

The andl and testl should be folded into one andl.

Code is reduced from ffmpeg h264 decoder. It's easy to work around by reordering source lines, so not too important.