[CodeGen] Fix hashing for MO_ExternalSymbol MachineOperands.
We were hashing the string pointer, not the string, so two instructions
could be identical (isIdenticalTo), but have different hash codes.
This showed up as a very rare, non-deterministic assertion failure
rehashing a DenseMap constructed by MachineOutliner. So there's no
"real" testcase, just a unittest which checks that the hash function
behaves correctly.
I'm a little scared fixing this is going to cause a regression in
outlining or MachineCSE, but hopefully we won't run into any issues.
Differential Revision: https://reviews.llvm.org/D61975
llvm-svn: 362281
diff --git a/llvm/unittests/CodeGen/MachineOperandTest.cpp b/llvm/unittests/CodeGen/MachineOperandTest.cpp
index cfedfa9..faa471f 100644
--- a/llvm/unittests/CodeGen/MachineOperandTest.cpp
+++ b/llvm/unittests/CodeGen/MachineOperandTest.cpp
@@ -398,4 +398,14 @@
ASSERT_TRUE(OS.str() == "intpred(eq)");
}
+TEST(MachineOperandTest, HashValue) {
+ char SymName1[] = "test";
+ char SymName2[] = "test";
+ MachineOperand MO1 = MachineOperand::CreateES(SymName1);
+ MachineOperand MO2 = MachineOperand::CreateES(SymName2);
+ ASSERT_NE(SymName1, SymName2);
+ ASSERT_EQ(hash_value(MO1), hash_value(MO2));
+ ASSERT_TRUE(MO1.isIdenticalTo(MO2));
+}
+
} // end namespace