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[PATCH AArch64]Handle wrong cost for addition of minus immediate in aarch64_rtx_costs.

From: "Bin Cheng" <bin dot cheng at arm dot com>
To: <gcc-patches at gcc dot gnu dot org>
Cc: "Marcus Shawcroft" <Marcus dot Shawcroft at arm dot com>, "James Greenhalgh" <James dot Greenhalgh at arm dot com>
Date: Fri, 26 Jun 2015 16:47:16 +0800
Subject: [PATCH AArch64]Handle wrong cost for addition of minus immediate in aarch64_rtx_costs.
Authentication-results: sourceware.org; auth=none

Hi,
The canonical form of subtract of immediate is (add op0 minus_imm), which is
supported with addsi3_aarch64 pattern on aarch64.  Unfortunately wrong cost
(8 rather than 4) is computed by aarch64_rtx_cost because it doesn't honor
the fact that it actually is a sub instruction.  This patch fixes it, is
this OK?

Thanks,
bin

2015-06-25  Bin Cheng  <bin.cheng@arm.com>

	* config/aarch64/aarch64.c (aarch64_rtx_costs): Handle addition of
	minus immediate.

Attachment: cost-add-minus-imm.txt
Description: Text document

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