Disable SROA debug info for variables with expressions #61168
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adrian-prantl
requested review from
mshockwave,
eeckstein,
DougGregor and
gottesmm
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@swift-ci test |
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FYI, this is in response to this build failure: https://ci.swift.org/job/swift-syntax-PR-macOS/609/consoleText |
| // TODO: Handle DIExpr that is already attached | ||
| NewDebugVarInfo->DIExpr = SILDebugInfoExpression::createFragment(VD); | ||
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| NewDebugVarInfo->DIExpr.append( |
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I was thinking: what if we don't clear out DIExpr from the existing VarInfo in SILDebugVariable::createFromAllocation so that this line will append fragment of the inner member. But then I realized we can't have more than one fragment inside a single DIExpression, right? If that's the case, then I do think this is the best solution we have now (until we have the infrastructure to merge two fragments inside a DIExpression)
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You're right — just appending the fragments would be the right thing to do, but it's currently not actually supported. I don't think there's much missing from making this work though.
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Cool! then I think this LGTM.
Currently the SROA just overwrites already-existing expressions on variables. When SROA is recursively run on a data structure this leads to nonsensical expressions such as type $*Outer, expr op_fragment:#Inner.x instead of type $*Outer, expr op_fragment:#Outer.inner op_fragment:#Inner.x The (nonsensical) LLVM IR generated from this violates some assumptions in LLVM for example, if a struct has multiple members of the same type, you can end up with multiple dbg.declare intrinsics claiming to describe the same variable). As a quick fix, this patch detects this situation and drops the debug info. A proper fix shouldn't be too difficult to implement though. rdar://99874371
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@swift-ci test |
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The windows build failure looks unrelated. |
Currently the SROA just overwrites already-existing expressions on variables. When SROA is recursively run on a data structure this leads to nonsensical expressions such as
type $*Outer, expr op_fragment:#Inner.x
instead of
type $*Outer, expr op_fragment:#Outer.inner op_fragment:#Inner.x
The (nonsensical) LLVM IR generated from this violates some assumptions in LLVM for example, if a struct has multiple members of the same type, you can end up with multiple dbg.declare intrinsics claiming to describe the same variable). As a quick fix, this patch detects this situation and drops the debug info. A proper fix shouldn't be too difficult to implement though.
rdar://99874371