llvm-project

History

Andrea Di Biagio 5578ec32f9 [MCA] Fixed a bug where loads and stores were sometimes incorrectly marked as depedent. Fixes PR45793. This fixes a regression introduced by a very old commit `280ac1fd1d` (was llvm-svn 361950). Commit `280ac1fd1d` redesigned the logic in the LSUnit with the goal of speeding up isReady() queries, and stabilising the LSUnit API (while also making the load store unit more customisable). The concept of MemoryGroup (effectively an alias set) was added by that commit to better describe and track dependencies between memory operations. However, that concept was not just used for alias dependencies, but it was also used for describing memory "order" dependencies (enforced by the memory consistency model). Instructions of a same memory group were considered "equivalent" as in: independent operations that can potentially execute in parallel. The problem was that the cost of a dependency (in terms of number of cycles) should have been different for "order" dependency. Instructions in an order dependency simply have to have to wait until their predecessors are "issued" to an underlying pipeline (rather than having to wait until predecessors have beeng fully executed). For simple "order" dependencies, this was effectively introducing an artificial delay on the "issue" of independent loads and stores. This patch fixes the issue and adds a new test named 'independent-load-stores.s' to a bunch of x86 targets. That test contains the reproducible posted by Fabian Ritter on PR45793. I had to rerun the update-mca-tests script on several files. To avoid expected regressions on some Exynos tests, I have added a -noalias=false flag (to match the old strict behavior on latencies). Some tests for processor Barcelona are improved/fixed by this change and they now show better results. In a few tests we were incorrectly counting the time spent by instructions in a scheduler queue. In one case in particular we now correctly see a store executed out of order. That test was affected by the same underlying issue reported as PR45793. Reviewers: mattd Differential Revision: https://reviews.llvm.org/D79351		2020-05-05 10:25:36 +01:00
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benchmarks	…
bindings	Update go bindings for `2dea3f1298`	2020-04-22 19:02:59 +02:00
cmake	[cmake] restrict object library dependency generation to PUBLIC libraries	2020-05-04 14:12:42 -07:00
docs	[llvm-dwarfdump][Stats] Clean up	2020-05-04 09:35:40 +02:00
examples	[examples] Fix an incomplete comment.	2020-05-01 11:06:41 -07:00
include	[MCA] Fixed a bug where loads and stores were sometimes incorrectly marked as depedent. Fixes PR45793.	2020-05-05 10:25:36 +01:00
lib	[MCA] Fixed a bug where loads and stores were sometimes incorrectly marked as depedent. Fixes PR45793.	2020-05-05 10:25:36 +01:00
projects	…
resources	…
runtimes	…
test	[MCA] Fixed a bug where loads and stores were sometimes incorrectly marked as depedent. Fixes PR45793.	2020-05-05 10:25:36 +01:00
tools	[dsymutil] Thread the VFS through dsymutil (NFC)	2020-05-04 20:21:33 -07:00
unittests	[CodeGen] Fix warnings due to SelectionDAG::getSplatSourceVector	2020-05-05 08:45:41 +01:00
utils	[lit] Create one output file when `--output` is specified more than once	2020-05-04 21:36:20 -07:00
.clang-format	…
.clang-tidy	…
.gitattributes	…
.gitignore	…
CMakeLists.txt	Revert "Temporarily revert "build: use `find_package(Python3)` if available""	2020-04-29 01:38:08 +00:00
CODE_OWNERS.TXT	…
CREDITS.TXT	…
LICENSE.TXT	…
LLVMBuild.txt	…
README.txt	…
RELEASE_TESTERS.TXT	…
configure	…
llvm.spec.in	…

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