Diffusion LLVM Github Monorepo dec624682e06

[MachineCSE][MachinePRE] Avoid hoisting code from code regions into hot BBs.
dec624682e06
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Authored by lkail on Jul 19 2019, 5:58 AM.

Description

[MachineCSE][MachinePRE] Avoid hoisting code from code regions into hot BBs.

Summary:
Current PRE hoists common computations into
CMBB = DT->findNearestCommonDominator(MBB, MBB1).
However, if CMBB is in a hot loop body, we might get performance
degradation.

Differential Revision: https://reviews.llvm.org/D64394

llvm-svn: 366570

Details

Committed

lkail

Jul 19 2019, 5:58 AM

Differential Revision

D64394: [MachineCSE][MachinePRE] Do not hoist common computations into hot BBs

Parents

rGe238a4c7570a: [X86] for split stack, not save/restore nested arg if unused

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Event Timeline

lkail committed rGdec624682e06: [MachineCSE][MachinePRE] Avoid hoisting code from code regions into hot BBs. (authored by lkail).Jul 19 2019, 5:58 AM

Should be backported to 9.0 branch?

Hi @xbolva00 , I have some concern that @anton-afanasyev might have plan to revert some patches related to these files. If not so, I'll backport it to 9.0.

Changes (5)

				Path	Packages
	M			llvm/lib/CodeGen/MachineCSE.cpp
	M			llvm/test/CodeGen/AArch64/O3-pipeline.ll
	M			llvm/test/CodeGen/ARM/O3-pipeline.ll
	M			llvm/test/CodeGen/PowerPC/machine-pre.ll
	M			llvm/test/CodeGen/X86/O3-pipeline.ll