Redundant limit check for switch

[Piotr Fusik <pfusik at op dot pl>]

The following code:

#include <stdio.h>

void Switch4(int x) {
    switch (x & 7) {
    case 0: printf("0\n"); break;
    case 1: printf("1\n"); break;
    case 2: printf("2\n"); break;
    case 3: printf("3\n"); break;
    case 4: printf("4\n"); break;
    case 5: printf("5\n"); break;
    case 6: printf("6\n"); break;
    case 7: printf("7\n"); break;
    }
}

void Switch256(int x) {
    switch ((unsigned char) x) {
    case 0: printf("0\n"); break;
    case 1: printf("1\n"); break;
    case 2: printf("2\n"); break;
    // ... (all 256 cases)
    }
}

when compiled with:
gcc -S -O3 fullswitch.c

produces the following:

	...
.globl _Switch4
	.def	_Switch4;	.scl	2;	.type	32;	.endef
_Switch4:
	pushl	%ebp
	movl	%esp, %ebp
	movl	8(%ebp), %eax
	andl	$7, %eax
	cmpl	$7, %eax
	ja	L12
	jmp	*L11(,%eax,4)
	...
.globl _Switch256
	.def	_Switch256;	.scl	2;	.type	32;	.endef
_Switch256:
	pushl	%ebp
	movl	%esp, %ebp
	movzbl	8(%ebp), %eax
	cmpl	$255, %eax
	ja	L273
	jmp	*L272(,%eax,4)


cmpl+ja are redundant in both cases.
Do you think it is possible for gcc to optimize them away?

An example of a real program with all 256 cases for unsigned char is Atari800. We use table-driven goto * there for better performance.