forked from OSchip/llvm-project
d006c6938b
The included test case is derived from one of the GCC compatibility tests. The problem arises after the selection DAG has been converted to type-legalized form. The combiner first sees a 64-bit load that can be converted into a pre-increment form. The original load feeds into a SRL that isolates the upper 32 bits of the loaded doubleword. This looks like an opportunity for DAGCombiner::ReduceLoadWidth() to replace the 64-bit load with a 32-bit load. However, this transformation is not valid, as the replacement load is not a pre-increment load. The pre-increment load produces an extra result, which feeds a subsequent add instruction. The replacement load only has one result value, and this value is propagated to all uses of the pre- increment load, including the add. Because the add is looking for the second result value as its operand, it ends up attempting to add a constant to a token chain, resulting in a crash. So the patch simply disables this transformation for any load with more than two result values. llvm-svn: 172480 |
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