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[RS4GC] Add an option to suppress vector splitting

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At the moment, this is essentially a diangostic option so that I can start collecting failing test cases, but we will eventually migrate to removing the vector splitting code entirely.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@257015 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Philip Reames 2016-01-07 02:20:11 +00:00
parent ab240104f0
commit c983c66023
1 changed files with 20 additions and 9 deletions
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29
lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
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@ -78,6 +78,13 @@ static cl::opt<bool>
AllowStatepointWithNoDeoptInfo("rs4gc-allow-statepoint-with-no-deopt-info",
cl::Hidden, cl::init(true));
/// Should we split vectors of pointers into their individual elements? This
/// is known to be buggy, but the alternate implementation isn't yet ready.
/// This is purely to provide a debugging and dianostic hook until the vector
/// split is replaced with vector relocations.
static cl::opt<bool> UseVectorSplit("rs4gc-split-vector-values", cl::Hidden,
cl::init(true));
namespace {
struct RewriteStatepointsForGC : public ModulePass {
static char ID; // Pass identification, replacement for typeid
@ -2380,15 +2387,19 @@ static bool insertParsePoints(Function &F, DominatorTree &DT,
// Do a limited scalarization of any live at safepoint vector values which
// contain pointers. This enables this pass to run after vectorization at
// the cost of some possible performance loss. TODO: it would be nice to
// natively support vectors all the way through the backend so we don't need
// to scalarize here.
for (size_t i = 0; i < Records.size(); i++) {
PartiallyConstructedSafepointRecord &Info = Records[i];
Instruction *Statepoint = ToUpdate[i].getInstruction();
splitVectorValues(cast<Instruction>(Statepoint), Info.LiveSet,
Info.PointerToBase, DT);
}
// the cost of some possible performance loss. Note: This is known to not
// handle updating of the side tables correctly which can lead to relocation
// bugs when the same vector is live at multiple statepoints. We're in the
// process of implementing the alternate lowering - relocating the
// vector-of-pointers as first class item and updating the backend to
// understand that - but that's not yet complete.
if (UseVectorSplit)
for (size_t i = 0; i < Records.size(); i++) {
PartiallyConstructedSafepointRecord &Info = Records[i];
Instruction *Statepoint = ToUpdate[i].getInstruction();
splitVectorValues(cast<Instruction>(Statepoint), Info.LiveSet,
Info.PointerToBase, DT);
}
// In order to reduce live set of statepoint we might choose to rematerialize
// some values instead of relocating them. This is purely an optimization and