[DependenceAnalysis] Improve debug messages #156367
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@llvm/pr-subscribers-llvm-analysis Author: Sebastian Pop (sebpop) ChangesFull diff: https://github.com/llvm/llvm-project/pull/156367.diff 1 Files Affected:
diff --git a/llvm/lib/Analysis/DependenceAnalysis.cpp b/llvm/lib/Analysis/DependenceAnalysis.cpp
index f33e04e804e3d..da86a8d2cc9c0 100644
--- a/llvm/lib/Analysis/DependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DependenceAnalysis.cpp
@@ -3419,13 +3419,24 @@ bool DependenceInfo::tryDelinearizeFixedSize(
size_t SSize = Subscripts.size();
for (size_t I = 1; I < SSize; ++I) {
const SCEV *S = Subscripts[I];
- if (!isKnownNonNegative(S, Ptr))
+ if (!isKnownNonNegative(S, Ptr)) {
+ LLVM_DEBUG({
+ dbgs() << "Check failed: !isKnownNonNegative(S, Ptr)\n";
+ dbgs() << " S: " << *S << "\n" << " Ptr: " << *Ptr << "\n";
+ });
return false;
+ }
if (auto *SType = dyn_cast<IntegerType>(S->getType())) {
const SCEV *Range = SE->getConstant(
ConstantInt::get(SType, DimensionSizes[I - 1], false));
- if (!isKnownLessThan(S, Range))
+ if (!isKnownLessThan(S, Range)) {
+ LLVM_DEBUG({
+ dbgs() << "Check failed: !isKnownLessThan(S, Range)\n";
+ dbgs() << " S: " << *S << "\n"
+ << " Range: " << *Range << "\n";
+ });
return false;
+ }
}
}
return true;
@@ -3433,6 +3444,7 @@ bool DependenceInfo::tryDelinearizeFixedSize(
if (!AllIndicesInRange(SrcSizes, SrcSubscripts, SrcPtr) ||
!AllIndicesInRange(DstSizes, DstSubscripts, DstPtr)) {
+ LLVM_DEBUG(dbgs() << "Check failed: AllIndicesInRange.\n");
SrcSubscripts.clear();
DstSubscripts.clear();
return false;
@@ -3500,17 +3512,27 @@ bool DependenceInfo::tryDelinearizeParametricSize(
// to the dependency checks.
if (!DisableDelinearizationChecks)
for (size_t I = 1; I < Size; ++I) {
- if (!isKnownNonNegative(SrcSubscripts[I], SrcPtr))
- return false;
-
- if (!isKnownLessThan(SrcSubscripts[I], Sizes[I - 1]))
- return false;
-
- if (!isKnownNonNegative(DstSubscripts[I], DstPtr))
- return false;
+ bool SNN = isKnownNonNegative(SrcSubscripts[I], SrcPtr);
+ bool DNN = isKnownNonNegative(DstSubscripts[I], DstPtr);
+ bool SLT = isKnownLessThan(SrcSubscripts[I], Sizes[I - 1]);
+ bool DLT = isKnownLessThan(DstSubscripts[I], Sizes[I - 1]);
+ if (SNN && DNN && SLT && DLT)
+ continue;
- if (!isKnownLessThan(DstSubscripts[I], Sizes[I - 1]))
- return false;
+ LLVM_DEBUG({
+ dbgs() << "Delinearization checks failed: can't prove the following\n";
+ if (!SNN)
+ dbgs() << " isKnownNonNegative(" << *SrcSubscripts[I] << ")\n";
+ if (!DNN)
+ dbgs() << " isKnownNonNegative(" << *DstSubscripts[I] << ")\n";
+ if (!SLT)
+ dbgs() << " isKnownLessThan(" << *SrcSubscripts[I] << ", "
+ << *Sizes[I - 1] << ")\n";
+ if (!DLT)
+ dbgs() << " isKnownLessThan(" << *DstSubscripts[I] << ", "
+ << *Sizes[I - 1] << ")\n";
+ });
+ return false;
}
return true;
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If other debug messages need cleaning up, that's unrelated to this change. I think it is super useful to understand why delinearization fails and so these debug messages seem useful. I will let @sebpop answer your question, but I am happy to LGTM this. |
| } | ||
| } | ||
| return true; | ||
| }; | ||
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| if (!AllIndicesInRange(SrcSizes, SrcSubscripts, SrcPtr) || | ||
| !AllIndicesInRange(DstSizes, DstSubscripts, DstPtr)) { | ||
| LLVM_DEBUG(dbgs() << "Check failed: AllIndicesInRange.\n"); |
There was a problem hiding this comment.
I think this is redundant.
There was a problem hiding this comment.
Currently, when the range check fails, the debug output looks like:
Check failed: !isKnownLessThan(S, Range)
S: {0,+,1}<nuw><nsw><%loop.j>
Range: 256
Check failed: AllIndicesInRange.
I think the last line is redundant.
| if (!SNN) | ||
| dbgs() << " isKnownNonNegative(" << *SrcSubscripts[I] << ")\n"; | ||
| if (!DNN) | ||
| dbgs() << " isKnownNonNegative(" << *DstSubscripts[I] << ")\n"; | ||
| if (!SLT) | ||
| dbgs() << " isKnownLessThan(" << *SrcSubscripts[I] << ", " | ||
| << *Sizes[I - 1] << ")\n"; | ||
| if (!DLT) | ||
| dbgs() << " isKnownLessThan(" << *DstSubscripts[I] << ", " | ||
| << *Sizes[I - 1] << ")\n"; | ||
| }); |
There was a problem hiding this comment.
Can you unify the format? The messages in tryDelinearizeFixedSize dump like
Check failed: !isKnownNonNegative(S, Ptr)
S: ...
Ptr: ...
But this one prints
isKnownNonNegative(..., ...)
There was a problem hiding this comment.
Format doesn't matter.
It's not like we're using a parser for the debug messages.
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I'm not talking about parsing debug outputs. The point here is to prevent an increase in messy or unorganized logging.
After posting my earlier comment, I realized that these messages should probably be placed inside isKnownNonNegative and isKnownLessThan, respectively.
Debug messages are supposed to tell at a glance without starting a debugger why something is discarded, etc. |
| } | ||
| } | ||
| return true; | ||
| }; | ||
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| if (!AllIndicesInRange(SrcSizes, SrcSubscripts, SrcPtr) || | ||
| !AllIndicesInRange(DstSizes, DstSubscripts, DstPtr)) { | ||
| LLVM_DEBUG(dbgs() << "Check failed: AllIndicesInRange.\n"); |
There was a problem hiding this comment.
Currently, when the range check fails, the debug output looks like:
Check failed: !isKnownLessThan(S, Range)
S: {0,+,1}<nuw><nsw><%loop.j>
Range: 256
Check failed: AllIndicesInRange.
I think the last line is redundant.
| if (!SNN) | ||
| dbgs() << " isKnownNonNegative(" << *SrcSubscripts[I] << ")\n"; | ||
| if (!DNN) | ||
| dbgs() << " isKnownNonNegative(" << *DstSubscripts[I] << ")\n"; | ||
| if (!SLT) | ||
| dbgs() << " isKnownLessThan(" << *SrcSubscripts[I] << ", " | ||
| << *Sizes[I - 1] << ")\n"; | ||
| if (!DLT) | ||
| dbgs() << " isKnownLessThan(" << *DstSubscripts[I] << ", " | ||
| << *Sizes[I - 1] << ")\n"; | ||
| }); |
There was a problem hiding this comment.
I'm not talking about parsing debug outputs. The point here is to prevent an increase in messy or unorganized logging.
After posting my earlier comment, I realized that these messages should probably be placed inside isKnownNonNegative and isKnownLessThan, respectively.
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