diff options
Diffstat (limited to 'lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp')
-rw-r--r-- | lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index a471aab..81efc0b 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -76,12 +76,15 @@ LimitFPPrecision("limit-float-precision", // load clustering may not complete in reasonable time. It is difficult to // recognize and avoid this situation within each individual analysis, and // future analyses are likely to have the same behavior. Limiting DAG width is -// the safe approach, and will be especially important with global DAGs. See -// 2010-11-11-ReturnBigBuffer.ll. +// the safe approach, and will be especially important with global DAGs. // // MaxParallelChains default is arbitrarily high to avoid affecting // optimization, but could be lowered to improve compile time. Any ld-ld-st-st -// sequence over this should have been converted to llvm.memcpy by the frontend. +// sequence over this should have been converted to llvm.memcpy by the +// frontend. It easy to induce this behavior with .ll code such as: +// %buffer = alloca [4096 x i8] +// %data = load [4096 x i8]* %argPtr +// store [4096 x i8] %data, [4096 x i8]* %buffer static cl::opt<unsigned> MaxParallelChains("dag-chain-limit", cl::desc("Max parallel isel dag chains"), cl::init(64), cl::Hidden); |