[DebugInfo][LoopVectorizer][NFC] Use unknown annotations for more instructions

[SLTozer]

Some recent patches have added more non-annotated empty locations to the loop vectorizer, resulting in errors reported on the DebugLoc coverage tracking buildbot:
https://lab.llvm.org/staging/#/builders/222/builds/1938

This patch adds "unknown" annotations in place of the empty locations, allowing the buildbot to ignore them for now.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

@llvm/pr-subscribers-vectorizers

Author: Stephen Tozer (SLTozer)

Changes

Some recent patches have added more non-annotated empty locations to the loop vectorizer, resulting in errors reported on the DebugLoc coverage tracking buildbot:
https://lab.llvm.org/staging/#/builders/222/builds/1938

This patch adds "unknown" annotations in place of the empty locations, allowing the buildbot to ignore them for now.

---

Full diff: https://github.com/llvm/llvm-project/pull/170522.diff

1 Files Affected:

• (modified) llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp (+4-4)

diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 38024aa6897fc..6429ff8e5e1b9 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -967,7 +967,7 @@ static VPValue *optimizeLatchExitInductionUser(
   VPValue *Step = WideIV->getStepValue();
   Type *ScalarTy = TypeInfo.inferScalarType(WideIV);
   if (ScalarTy->isIntegerTy())
-    return B.createNaryOp(Instruction::Sub, {EndValue, Step}, {}, "ind.escape");
+    return B.createNaryOp(Instruction::Sub, {EndValue, Step}, DebugLoc::getUnknown(), "ind.escape");
   if (ScalarTy->isPointerTy()) {
     Type *StepTy = TypeInfo.inferScalarType(Step);
     auto *Zero = Plan.getConstantInt(StepTy, 0);
@@ -3770,11 +3770,11 @@ void VPlanTransforms::handleUncountableEarlyExit(VPBasicBlock *EarlyExitingVPBB,
     if (!IncomingFromEarlyExit->isLiveIn()) {
       // Update the incoming value from the early exit.
       VPValue *FirstActiveLane = EarlyExitB.createNaryOp(
-          VPInstruction::FirstActiveLane, {CondToEarlyExit}, nullptr,
+          VPInstruction::FirstActiveLane, {CondToEarlyExit}, DebugLoc::getUnknown(),
           "first.active.lane");
       IncomingFromEarlyExit = EarlyExitB.createNaryOp(
           VPInstruction::ExtractLane, {FirstActiveLane, IncomingFromEarlyExit},
-          nullptr, "early.exit.value");
+          DebugLoc::getUnknown(), "early.exit.value");
       ExitIRI->setOperand(EarlyExitIdx, IncomingFromEarlyExit);
     }
   }
@@ -4990,7 +4990,7 @@ void VPlanTransforms::updateScalarResumePhis(
            "Cannot handle loops with uncountable early exits");
     if (IsFOR)
       ResumeFromVectorLoop = MiddleBuilder.createNaryOp(
-          VPInstruction::ExtractLastElement, {ResumeFromVectorLoop}, {},
+          VPInstruction::ExtractLastElement, {ResumeFromVectorLoop}, DebugLoc::getUnknown(),
           "vector.recur.extract");
     ResumePhiR->setName(IsFOR ? "scalar.recur.init" : "bc.merge.rdx");
     ResumePhiR->setOperand(0, ResumeFromVectorLoop);

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[artagnon]

LGTM, with formatting fixed, thanks!

[artagnon]

Out of curiosity, when are we supposed to use DebugLoc::getCompilerGenerated()?

[SLTozer]

Out of curiosity, when are we supposed to use DebugLoc::getCompilerGenerated()?

Thanks for the quick review!

We use compiler generated annotations for instructions that are generated by the compiler but don't correspond to user code; there are some examples in global variable opt, loop unswitching, and tail recursion elimination right now, and also Clang applies it to any instructions it generates that weren't assigned a source location. It could also be appropriate here, the reason I've gone with "unknowns" is that I don't understand VPlan well enough to confidently select a different annotation.

Further down the line I intend to work through the "unknown" annotations in the vectorizers to either rewrite them to more accurate annotations or to see if there's a way the instructions could receive valid source locations instead.

[artagnon]

We use compiler generated annotations for instructions that are generated by the compiler but don't correspond to user code; there are some examples in global variable opt, loop unswitching, and tail recursion elimination right now, and also Clang applies it to any instructions it generates that weren't assigned a source location

Thanks for the explanation, and examples! You're right that VPlan is somewhat special, and the compiler-generated annotations might not work, since it's not exactly IR, but rather a separate overlay on the IR. We have to think about how to get accurate DebugLocs in VPlan some more.

[fhahn]

LGTM, thanks