This reapplies r207235 with an additional bugfixes caught by the msan
buildbot - do not insert debug intrinsics before phi nodes.
Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.
Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.
This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine.ll testcase and included source
rdar://problem/16679879
http://reviews.llvm.org/D3374
llvm-svn: 207269
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 552f715..9c78a99 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1037,20 +1037,26 @@
AllocaInst *AI = dyn_cast_or_null<AllocaInst>(DDI->getAddress());
// If this is an alloca for a scalar variable, insert a dbg.value
// at each load and store to the alloca and erase the dbg.declare.
+ // The dbg.values allow tracking a variable even if it is not
+ // stored on the stack, while the dbg.declare can only describe
+ // the stack slot (and at a lexical-scope granularity). Later
+ // passes will attempt to elide the stack slot.
if (AI && !AI->isArrayAllocation()) {
-
- // We only remove the dbg.declare intrinsic if all uses are
- // converted to dbg.value intrinsics.
- bool RemoveDDI = true;
for (User *U : AI->users())
if (StoreInst *SI = dyn_cast<StoreInst>(U))
ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
else if (LoadInst *LI = dyn_cast<LoadInst>(U))
ConvertDebugDeclareToDebugValue(DDI, LI, DIB);
- else
- RemoveDDI = false;
- if (RemoveDDI)
- DDI->eraseFromParent();
+ else if (CallInst *CI = dyn_cast<CallInst>(U)) {
+ // This is a call by-value or some other instruction that
+ // takes a pointer to the variable. Insert a *value*
+ // intrinsic that describes the alloca.
+ auto DbgVal =
+ DIB.insertDbgValueIntrinsic(AI, 0,
+ DIVariable(DDI->getVariable()), CI);
+ DbgVal->setDebugLoc(DDI->getDebugLoc());
+ }
+ DDI->eraseFromParent();
}
}
return true;