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author | Bjorn Pettersson <bjorn.a.pettersson@ericsson.com> | 2019-10-25 19:03:18 +0200 |
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committer | Bjorn Pettersson <bjorn.a.pettersson@ericsson.com> | 2019-11-01 16:25:32 +0100 |
commit | 56c22931bdfafe8257e610cb9f29b9d64478f812 (patch) | |
tree | 2f336be899b6ffec57ba7f2d16f96d027c4b8774 /llvm/lib/CodeGen/LiveDebugVariables.cpp | |
parent | 449882b5442aa5138b5a89f56996ed990a3ead20 (diff) | |
download | llvm-56c22931bdfafe8257e610cb9f29b9d64478f812.zip llvm-56c22931bdfafe8257e610cb9f29b9d64478f812.tar.gz llvm-56c22931bdfafe8257e610cb9f29b9d64478f812.tar.bz2 |
[LDV][RAGreedy] Inform LiveDebugVariables about new VRegs added by InlineSpiller
Summary:
Make sure RAGreedy informs LiveDebugVariables about new VRegs
that is introduced at spill by InlineSpiller.
Consider this example
LDV: !"var" [48r;128r):0 Loc0=%2
48B %2 = ...
...
128B %7 = ADD %2, ...
If %2 is spilled the InlineSpiller will insert spill/reload
instructions and introduces some new vregs. So we get
48B %4 = ...
56B spill %4
...
120B reload %5
128B %3 = ADD %5, ...
In the past we did not inform LDV about this, and when reintroducing
DBG_VALUE instruction LDV still got information that "var" had the
location of the spilled register %2 for the interval [48r;128r).
The result was bad, since we mapped "var" to the spill slot even
before the spill happened:
%4 = ...
DBG_VALUE %spill.0, !"var"
spill %4 to %spill.0
...
reload %5
%3 = ADD %5, ...
This patch will inform LDV about the interval split introduced
due to spilling. So the location map in LDV will become
!"var" [48r;56r):1 [56r;120r):0 [120r;128r):2 Loc0=%2 Loc1=%4 Loc2=%5
And when inserting DBG_VALUE instructions we get
%4 = ...
DBG_VALUE %4, !"var"
spill %4 to %spill.0
DBG_VALUE %spill.0, !"var"
...
reload %5
DBG_VALUE %5, !"var"
%3 = ADD %5, ...
Fixes: https://bugs.llvm.org/show_bug.cgi?id=38899
Reviewers: jmorse, vsk, aprantl
Reviewed By: jmorse
Subscribers: dstenb, wuzish, MatzeB, qcolombet, nemanjai, hiraditya, jsji, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69584
Diffstat (limited to 'llvm/lib/CodeGen/LiveDebugVariables.cpp')
-rw-r--r-- | llvm/lib/CodeGen/LiveDebugVariables.cpp | 44 |
1 files changed, 27 insertions, 17 deletions
diff --git a/llvm/lib/CodeGen/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp index 253bdbb..cace044 100644 --- a/llvm/lib/CodeGen/LiveDebugVariables.cpp +++ b/llvm/lib/CodeGen/LiveDebugVariables.cpp @@ -255,6 +255,25 @@ public: return locations.size() - 1; } + /// Remove (recycle) a location number. If \p LocNo still is used by the + /// locInts nothing is done. + void removeLocationIfUnused(unsigned LocNo) { + // Bail out if LocNo still is used. + for (LocMap::const_iterator I = locInts.begin(); I.valid(); ++I) { + DbgValueLocation Loc = I.value(); + if (Loc.locNo() == LocNo) + return; + } + // Remove the entry in the locations vector, and adjust all references to + // location numbers above the removed entry. + locations.erase(locations.begin() + LocNo); + for (LocMap::iterator I = locInts.begin(); I.valid(); ++I) { + DbgValueLocation Loc = I.value(); + if (!Loc.isUndef() && Loc.locNo() > LocNo) + I.setValueUnchecked(Loc.changeLocNo(Loc.locNo() - 1)); + } + } + /// Ensure that all virtual register locations are mapped. void mapVirtRegs(LDVImpl *LDV); @@ -1073,23 +1092,14 @@ UserValue::splitLocation(unsigned OldLocNo, ArrayRef<unsigned> NewRegs, } } - // Finally, remove any remaining OldLocNo intervals and OldLocNo itself. - locations.erase(locations.begin() + OldLocNo); - LocMapI.goToBegin(); - while (LocMapI.valid()) { - DbgValueLocation v = LocMapI.value(); - if (v.locNo() == OldLocNo) { - LLVM_DEBUG(dbgs() << "Erasing [" << LocMapI.start() << ';' - << LocMapI.stop() << ")\n"); - LocMapI.erase(); - } else { - // Undef values always have location number UndefLocNo, so don't change - // locNo in that case. See getLocationNo(). - if (!v.isUndef() && v.locNo() > OldLocNo) - LocMapI.setValueUnchecked(v.changeLocNo(v.locNo() - 1)); - ++LocMapI; - } - } + // Finally, remove OldLocNo unless it is still used by some interval in the + // locInts map. One case when OldLocNo still is in use is when the register + // has been spilled. In such situations the spilled register is kept as a + // location until rewriteLocations is called (VirtRegMap is mapping the old + // register to the spill slot). So for a while we can have locations that map + // to virtual registers that have been removed from both the MachineFunction + // and from LiveIntervals. + removeLocationIfUnused(OldLocNo); LLVM_DEBUG({ dbgs() << "Split result: \t"; |