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author | Chris Lattner <sabre@nondot.org> | 2006-03-06 17:58:04 +0000 |
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committer | Chris Lattner <sabre@nondot.org> | 2006-03-06 17:58:04 +0000 |
commit | 6af7ef8da874635f5f060ad19afb19811452b447 (patch) | |
tree | a456d4c917669830d67f058bf44d24406700ac63 | |
parent | adc5e5c85fdf188166690084675a971aa5e9f188 (diff) | |
download | external_llvm-6af7ef8da874635f5f060ad19afb19811452b447.zip external_llvm-6af7ef8da874635f5f060ad19afb19811452b447.tar.gz external_llvm-6af7ef8da874635f5f060ad19afb19811452b447.tar.bz2 |
update file comment
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26573 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp index dfd46b7..4d44d2d 100644 --- a/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp +++ b/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp @@ -7,9 +7,14 @@ // //===----------------------------------------------------------------------===// // -// This implements a simple two pass scheduler. The first pass attempts to push -// backward any lengthy instructions and critical paths. The second pass packs -// instructions into semi-optimal time slots. +// This implements bottom-up and top-down list schedulers, using standard +// algorithms. The basic approach uses a priority queue of available nodes to +// schedule. One at a time, nodes are taken from the priority queue (thus in +// priority order), checked for legality to schedule, and emitted if legal. +// +// Nodes may not be legal to schedule either due to structural hazards (e.g. +// pipeline or resource constraints) or because an input to the instruction has +// not completed execution. // //===----------------------------------------------------------------------===// |