[llvm] [IR] Fix null pointer dereference in Constant::toConstantRange() for ConstantByte (PR #193874)

[Nikita Popov via llvm-commits]

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@@ -868,5 +869,29 @@ TEST(ConstantsTest, Float128Test) {
   LLVMContextDispose(C);
 }
 
+TEST(ConstantsTest, ToConstantRangeConstantByteVector) {
+  LLVMContext Context;
+  // Use 7-bit ByteType so the vector is not folded into ConstantDataVector
+  // (ConstantDataSequential only supports 8/16/32/64-bit element types).
+  ByteType *B7Ty = Type::getByteNTy(Context, 7);
+
+  ConstantByte *CB1 = ConstantByte::get(B7Ty, 10);
+  ConstantByte *CB2 = ConstantByte::get(B7Ty, 20);
+  Constant *Elts[] = {CB1, CB2};
+  Constant *CV = ConstantVector::get(Elts);
+  ASSERT_TRUE(isa<ConstantVector>(CV));
+
+  ConstantRange CR = CV->toConstantRange();
+  EXPECT_TRUE(CR.contains(APInt(7, 10)));
+  EXPECT_TRUE(CR.contains(APInt(7, 20)));
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nikic wrote:

Would be better to check `EXPECT_EQ` with the actual range, rather than just two elements.

https://github.com/llvm/llvm-project/pull/193874