Petr Tesarik d069ed288a swiotlb: optimize get_max_slots()
Use a simple logical shift and increment to calculate the number of slots
taken by the DMA segment boundary.

At least GCC-13 is not able to optimize the expression, producing this
horrible assembly code on x86:

	cmpq	$-1, %rcx
	je	.L364
	addq	$2048, %rcx
	shrq	$11, %rcx
	movq	%rcx, %r13
.L331:
	// rest of the function here...

	// after function epilogue and return:
.L364:
	movabsq $9007199254740992, %r13
	jmp	.L331

After the optimization, the code looks more reasonable:

	shrq	$11, %r11
	leaq	1(%r11), %rbx

Signed-off-by: Petr Tesarik <petr.tesarik.ext@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
2023-08-08 10:29:21 -07:00
..
2023-08-08 10:29:21 -07:00
2023-07-01 08:58:41 -07:00
2022-12-21 14:31:52 -08:00
2023-06-27 21:24:18 -07:00
2023-07-30 11:27:22 -07:00
2022-08-29 19:47:03 -04:00
2022-09-26 10:13:13 -07:00
2023-03-24 11:01:29 +01:00
2023-06-28 15:51:08 -07:00
2023-04-20 22:55:35 -04:00
2023-06-09 17:44:15 -07:00
2023-07-01 08:26:23 -07:00
2023-07-06 10:06:04 -07:00
2023-06-28 16:05:21 -07:00
2023-06-27 16:32:52 -07:00