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* [MCA] Show aggregate over Average Wait times for the whole snippet (PR43219)Roman Lebedev2019-10-101-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: As disscused in https://bugs.llvm.org/show_bug.cgi?id=43219, i believe it may be somewhat useful to show //some// aggregates over all the sea of statistics provided. Example: ``` Average Wait times (based on the timeline view): [0]: Executions [1]: Average time spent waiting in a scheduler's queue [2]: Average time spent waiting in a scheduler's queue while ready [3]: Average time elapsed from WB until retire stage [0] [1] [2] [3] 0. 3 1.0 1.0 4.7 vmulps %xmm0, %xmm1, %xmm2 1. 3 2.7 0.0 2.3 vhaddps %xmm2, %xmm2, %xmm3 2. 3 6.0 0.0 0.0 vhaddps %xmm3, %xmm3, %xmm4 3 3.2 0.3 2.3 <total> ``` I.e. we average the averages. Reviewers: andreadb, mattd, RKSimon Reviewed By: andreadb Subscribers: gbedwell, arphaman, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D68714 llvm-svn: 374361
* [llvm-mca] Add fields "Total uOps" and "uOps Per Cycle" to the report ↵Andrea Di Biagio2018-08-291-1/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | generated by the SummaryView. This patch adds two new fields to the perf report generated by the SummaryView. Fields are now logically organized into two small groups; only the second group contains throughput indicators. Example: ``` Iterations: 100 Instructions: 300 Total Cycles: 414 Total uOps: 700 Dispatch Width: 4 uOps Per Cycle: 1.69 IPC: 0.72 Block RThroughput: 4.0 ``` This patch also updates the docs for llvm-mca. Due to the nature of this change, several tests in the tools/llvm-mca directory were affected, and had to be updated using script `update_mca_test_checks.py`. llvm-svn: 340946
* [llvm-mca] Use a different character to flag instructions with side-effects ↵Andrea Di Biagio2018-07-111-1/+1
| | | | | | | | | | | | | | | | | | | | | in the Instruction Info View. NFC This makes easier to identify changes in the instruction info flags. It also helps spotting potential regressions similar to the one recently introduced at r336728. Using the same character to mark MayLoad/MayStore/HasSideEffects is problematic for llvm-lit. When pattern matching substrings, llvm-lit consumes tabs and spaces. A change in position of the flag marker may not trigger a test failure. This patch only changes the character used for flag `hasSideEffects`. The reason why I didn't touch other flags is because I want to avoid spamming the mailing because of the massive diff due to the numerous tests affected by this change. In future, each instruction flag should be associated with a different character in the Instruction Info View. llvm-svn: 336797
* [llvm-mca][X86] Teach how to identify register writes that implicitly clear ↵Andrea Di Biagio2018-06-201-22/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | the upper portion of a super-register. This patch teaches llvm-mca how to identify register writes that implicitly zero the upper portion of a super-register. On X86-64, a general purpose register is implemented in hardware as a 64-bit register. Quoting the Intel 64 Software Developer's Manual: "an update to the lower 32 bits of a 64 bit integer register is architecturally defined to zero extend the upper 32 bits". Also, a write to an XMM register performed by an AVX instruction implicitly zeroes the upper 128 bits of the aliasing YMM register. This patch adds a new method named clearsSuperRegisters to the MCInstrAnalysis interface to help identify instructions that implicitly clear the upper portion of a super-register. The rest of the patch teaches llvm-mca how to use that new method to obtain the information, and update the register dependencies accordingly. I compared the kernels from tests clear-super-register-1.s and clear-super-register-2.s against the output from perf on btver2. Previously there was a large discrepancy between the estimated IPC and the measured IPC. Now the differences are mostly in the noise. Differential Revision: https://reviews.llvm.org/D48225 llvm-svn: 335113
* [llvm-mca] Add tests for XOP and AVX512 instructions that implicitly clear ↵Andrea Di Biagio2018-06-181-0/+86
the upper portion of a super-register. When the destination register of a XOP instruction is an XMM register, bits [255:128] of the corresponding YMM register are cleared. When the destination register of a EVEX encoded instruction is an XMM/YMM register, the upper bits of the corresponding ZMM are cleared. On processors that feature AVX512, a write to an XMM registers always clears the upper portion of the corresponding ZMM register if the instruction is VEX or EVEX encoded. These new tests show some interesting cases which aren't correctly analyzed by llvm-mca. The lack of knowledge related to the implicit update on the super-registers is addressed by D48225. llvm-svn: 334945
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