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Re: [PATCH] Fix scheduling undeterminism from sorting with DEBUG_INSNs
- From: Mike Stump <mikestump at comcast dot net>
- To: Maxim Kuvyrkov <maxim dot kuvyrkov at linaro dot org>
- Cc: Alexander Monakov <amonakov at ispras dot ru>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Ramana Radhakrishnan <ramana dot radhakrishnan at arm dot com>, Vladimir Makarov <vmakarov at redhat dot com>
- Date: Mon, 19 Jan 2015 07:48:37 -0800
- Subject: Re: [PATCH] Fix scheduling undeterminism from sorting with DEBUG_INSNs
- Authentication-results: sourceware.org; auth=none
- References: <1C9D1942-81E0-4245-BC86-CC8F191956F2 at linaro dot org> <alpine dot LNX dot 2 dot 11 dot 1501191627490 dot 8222 at monopod dot intra dot ispras dot ru> <EE067606-201A-493C-8F8C-BAE95DBB2566 at linaro dot org>
On Jan 19, 2015, at 5:41 AM, Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org> wrote:
> In A < B < C < A case all A, B and C are normal instructions. It is a pre-existing condition. When compiling without debug information we have ready list "A, B, C". When compiling with debug information, we have ready list "A, B, C, D" where "D" is DEBUG_INSN. Because we now have 4 elements to sort instead of 3, qsort can choose a different order of comparison _among_ A, B and C.
Not when the uid is mixed in it cannot. :-)