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Merged
merged 4 commits into from
Dec 25, 2024

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Lewuathe
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Vector::BroadCastOp expects the identical element type in folding. It causes the crash if the different source type is given to the SCCP pass. We need to guard the pass from crashing if the nonidentical element type is given, but still compatible. (e.g. index vs integer type)

#120193

@llvmbot
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llvmbot commented Dec 20, 2024

@llvm/pr-subscribers-mlir-vector

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Author: Kai Sasaki (Lewuathe)

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Vector::BroadCastOp expects the identical element type in folding. It causes the crash if the different source type is given to the SCCP pass. We need to guard the pass from crashing if the nonidentical element type is given, but still compatible. (e.g. index vs integer type)

#120193


Full diff: https://github.com/llvm/llvm-project/pull/120656.diff

2 Files Affected:

  • (modified) mlir/lib/Dialect/Vector/IR/VectorOps.cpp (+10-2)
  • (modified) mlir/test/Transforms/sccp.mlir (+13)
diff --git a/mlir/lib/Dialect/Vector/IR/VectorOps.cpp b/mlir/lib/Dialect/Vector/IR/VectorOps.cpp
index ad709813c6216a..4db3ba239eeaf3 100644
--- a/mlir/lib/Dialect/Vector/IR/VectorOps.cpp
+++ b/mlir/lib/Dialect/Vector/IR/VectorOps.cpp
@@ -2523,8 +2523,16 @@ OpFoldResult BroadcastOp::fold(FoldAdaptor adaptor) {
   if (!adaptor.getSource())
     return {};
   auto vectorType = getResultVectorType();
-  if (llvm::isa<IntegerAttr, FloatAttr>(adaptor.getSource()))
-    return DenseElementsAttr::get(vectorType, adaptor.getSource());
+  if (auto attr = llvm::dyn_cast<IntegerAttr>(adaptor.getSource())) {
+    if (vectorType.getElementType() != attr.getType())
+      return {};
+    return DenseElementsAttr::get(vectorType, attr);
+  }
+  if (auto attr = llvm::dyn_cast<FloatAttr>(adaptor.getSource())) {
+    if (vectorType.getElementType() != attr.getType())
+      return {};
+    return DenseElementsAttr::get(vectorType, attr);
+  }
   if (auto attr = llvm::dyn_cast<SplatElementsAttr>(adaptor.getSource()))
     return DenseElementsAttr::get(vectorType, attr.getSplatValue<Attribute>());
   return {};
diff --git a/mlir/test/Transforms/sccp.mlir b/mlir/test/Transforms/sccp.mlir
index dcae052c29c248..035fc5c21a38ef 100644
--- a/mlir/test/Transforms/sccp.mlir
+++ b/mlir/test/Transforms/sccp.mlir
@@ -246,3 +246,16 @@ func.func @op_with_region() -> (i32) {
 ^b:
   return %1 : i32
 }
+
+// CHECK-LABEL: no_crash_with_different_source_type
+func.func @no_crash_with_different_source_type() {
+  // CHECK: llvm.mlir.constant(0 : index) : i64
+  %0 = llvm.mlir.constant(0 : index) : i64
+  llvm.br ^b1(%0 : i64)
+^b1(%1: i64):  
+  llvm.br ^b2
+^b2: 
+  // CHECK: vector.broadcast %[[CST:.*]] : i64 to vector<128xi64>
+  %2 = vector.broadcast %1 : i64 to vector<128xi64>
+  llvm.return
+}

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Others, LGTM.

if (vectorType.getElementType() != attr.getType())
return {};
return DenseElementsAttr::get(vectorType, attr);
}
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What is the reason for separating the handling of int and float types?

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dyn_cast cannot take multiple arguments to be casted.

  if (auto attr = (llvm::dyn_cast<IntegerAttr>(adaptor.getSource()) || llvm::dyn_cast<FloatAttr>(adaptor.getSource()))) {

Even if I unioned the result of the cast like this, it causes the following error.

llvm-project/mlir/lib/Dialect/Vector/IR/VectorOps.cpp:2527:44: error: member reference base type 'bool' is not a structure or union
    if (vectorType.getElementType() != attr.getType())
                     

So we can only separate the logic to handle int and float separetely.

Vector::BroadCastOp expects the idential element type in folding. It
causes the crash if the different source type is given to the SCCP pass.
We need to guard the pass from crashing if the non-idential element type
is given, but still compatible. (e.g. index vs integer type)
@Lewuathe Lewuathe merged commit d3846ec into llvm:main Dec 25, 2024
8 checks passed
@Lewuathe Lewuathe deleted the fix-crash-with-sccp-pass branch December 25, 2024 03:19
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[Mlir] -sccp crashes in BuiltinAttributes.cpp:966: mlir::DenseElementsAttr::get
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