[SelectionDAG][RISCV][SVE] Harden fixed offset version of ComputeValu…

…eVTs against scalable offsets. Use getFixedValue instead of getKnownMinValue to convert TypeSize to uint64_t. I believe this would have caught the bug fixed by D157872. To prevent false failures, I had to treat a scalable 0 as if it is fixed value. Reviewed By: paulwalker-arm Differential Revision: https://reviews.llvm.org/D158115
llvm · Aug 21, 2023 · e620eac · e620eac
1 parent e223e45
commit e620eac
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Showing 2 changed files with 13 additions and 15 deletions.
diff --git a/llvm/include/llvm/Support/TypeSize.h b/llvm/include/llvm/Support/TypeSize.h
@@ -180,7 +180,7 @@ template <typename LeafTy, typename ValueTy> class FixedOrScalableQuantity {
   // Use in places where a scalable count doesn't make sense (e.g. non-vector
   // types, or vectors in backends which don't support scalable vectors).
   constexpr ScalarTy getFixedValue() const {
-    assert(!isScalable() &&
+    assert((!isScalable() || isZero()) &&
            "Request for a fixed element count on a scalable object");
     return getKnownMinValue();
   }

diff --git a/llvm/lib/CodeGen/Analysis.cpp b/llvm/lib/CodeGen/Analysis.cpp
@@ -140,15 +140,14 @@ void llvm::ComputeValueVTs(const TargetLowering &TLI, const DataLayout &DL,
                            SmallVectorImpl<uint64_t> *FixedOffsets,
                            uint64_t StartingOffset) {
   TypeSize Offset = TypeSize::get(StartingOffset, Ty->isScalableTy());
-  SmallVector<TypeSize, 4> Offsets;
-  if (FixedOffsets)
+  if (FixedOffsets) {
+    SmallVector<TypeSize, 4> Offsets;
     ComputeValueVTs(TLI, DL, Ty, ValueVTs, &Offsets, Offset);
-  else
-    ComputeValueVTs(TLI, DL, Ty, ValueVTs, nullptr, Offset);
-
-  if (FixedOffsets)
     for (TypeSize Offset : Offsets)
-      FixedOffsets->push_back(Offset.getKnownMinValue());
+      FixedOffsets->push_back(Offset.getFixedValue());
+  } else {
+    ComputeValueVTs(TLI, DL, Ty, ValueVTs, nullptr, Offset);
+  }
 }
 
 void llvm::ComputeValueVTs(const TargetLowering &TLI, const DataLayout &DL,
@@ -166,15 +165,14 @@ void llvm::ComputeValueVTs(const TargetLowering &TLI, const DataLayout &DL,
                            SmallVectorImpl<uint64_t> *FixedOffsets,
                            uint64_t StartingOffset) {
   TypeSize Offset = TypeSize::get(StartingOffset, Ty->isScalableTy());
-  SmallVector<TypeSize, 4> Offsets;
-  if (FixedOffsets)
+  if (FixedOffsets) {
+    SmallVector<TypeSize, 4> Offsets;
     ComputeValueVTs(TLI, DL, Ty, ValueVTs, MemVTs, &Offsets, Offset);
-  else
-    ComputeValueVTs(TLI, DL, Ty, ValueVTs, MemVTs, nullptr, Offset);
-
-  if (FixedOffsets)
     for (TypeSize Offset : Offsets)
-      FixedOffsets->push_back(Offset.getKnownMinValue());
+      FixedOffsets->push_back(Offset.getFixedValue());
+  } else {
+    ComputeValueVTs(TLI, DL, Ty, ValueVTs, MemVTs, nullptr, Offset);
+  }
 }
 
 void llvm::computeValueLLTs(const DataLayout &DL, Type &Ty,