RPCS3/llvm
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm.git synced 2026-07-21 03:05:26 -04:00
Code Issues Packages Projects Releases 10 Wiki Activity

[DebugInfo] Avoid crash from dropped fragments in LiveDebugValues

Browse Source 
This patch avoids a crash caused by DW_OP_LLVM_fragments being dropped
from DIExpressions by LiveDebugValues spill-restore code. The appearance
of a previously unseen fragment configuration confuses LDV, as documented
in PR42773, and reproduced by the test function this patch adds (Crashes
on a x86_64 debug build).

To avoid this, on spill restore, we now use fragment information from the
spilt-location-expression.

In addition, when spilling, we now don't spill any DBG_VALUE with a complex
expression, as it can't be safely restored and will definitely lead to an
incorrect variable location. The discussion of this is in D65368.

Differential Revision: https://reviews.llvm.org/D66284


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@369026 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jeremy Morse
2019-08-15 17:49:46 +00:00
parent c4ed7f707a
commit 5a682e0faa
2 changed files with 128 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/CodeGen/LiveDebugValues.cpp
+15 -2
View File
@@ -691,9 +691,17 @@ void LiveDebugValues::insertTransferDebugPair(
"No register supplied when handling a restore of a debug value");
MachineFunction *MF = MI.getMF();
DIBuilder DIB(*const_cast<Function &>(MF->getFunction()).getParent());
const DIExpression *NewExpr;
if (auto Fragment = DebugInstr->getDebugExpression()->getFragmentInfo())
NewExpr = *DIExpression::createFragmentExpression(DIB.createExpression(),
Fragment->OffsetInBits, Fragment->SizeInBits);
else
NewExpr = DIB.createExpression();
NewDebugInstr =
BuildMI(*MF, DebugInstr->getDebugLoc(), DebugInstr->getDesc(), false,
NewReg, DebugInstr->getDebugVariable(), DIB.createExpression());
NewReg, DebugInstr->getDebugVariable(), NewExpr);
VarLoc VL(*NewDebugInstr, LS);
ProcessVarLoc(VL, NewDebugInstr);
LLVM_DEBUG(dbgs() << "Creating DBG_VALUE inst for register restore: ";
@@ -848,9 +856,14 @@ void LiveDebugValues::transferSpillOrRestoreInst(MachineInstr &MI,
<< "\n");
}
// Check if the register or spill location is the location of a debug value.
// FIXME: Don't create a spill transfer if there is a complex expression,
// because we currently cannot recover the original expression on restore.
for (unsigned ID : OpenRanges.getVarLocs()) {
const MachineInstr *DebugInstr = &VarLocIDs[ID].MI;
if (TKind == TransferKind::TransferSpill &&
VarLocIDs[ID].isDescribedByReg() == Reg) {
VarLocIDs[ID].isDescribedByReg() == Reg &&
!DebugInstr->getDebugExpression()->isComplex()) {
LLVM_DEBUG(dbgs() << "Spilling Register " << printReg(Reg, TRI) << '('
<< VarLocIDs[ID].Var.getVar()->getName() << ")\n");
} else if (TKind == TransferKind::TransferRestore &&