[llvm-bugs] [Bug 32481] New: SelectionDAGBuilder produces vector nodes without vector support (results in crash)

via llvm-bugs llvm-bugs at lists.llvm.org
Thu Mar 30 23:48:32 PDT 2017


            Bug ID: 32481
           Summary: SelectionDAGBuilder produces vector nodes without
                    vector support (results in crash)
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Common Code Generator Code
          Assignee: unassignedbugs at nondot.org
          Reporter: paulsson at linux.vnet.ibm.com
                CC: llvm-bugs at lists.llvm.org

Created attachment 18201
  --> https://bugs.llvm.org/attachment.cgi?id=18201&action=edit
reduced test case

A small test case that includes the type <1 x i8>, causes SelectionDAG to crash
on an older subtarget which does not have vector support.

Should this vector type with one element not be converted to i8 during
SelectionDAG construction, if the target has no vector support? Or is target
required to handle also these types of vector values regardless of vector

Initial selection DAG: BB#1 'autogen_SD18500:CF244'
SelectionDAG has 24 nodes:
  t0: ch = EntryToken
  t16: f32 = ConstantFP<5.720826e-10>
  t17: f32 = ConstantFP<1.107380e+14>
  t18: ch = setune
            t3: i1 = setcc undef:i1, undef:i1, setule:ch
                  t5: i32,ch = CopyFromReg t0, Register:i32 %vreg0
                t7: i32 = AssertSext t5, ValueType:ch:i8
              t8: i8 = truncate t7
            t9: v1i8 = BUILD_VECTOR t8
          t11: v1i8 = select t3, t9, undef:v1i8
        t13: i32 = extract_vector_elt t11, Constant:i32<0>
      t15: ch = CopyToReg t0, Register:i32 %vreg1, t13
    t21: ch = brcond t15, Constant:i1<-1>, BasicBlock:ch<CF244 0x58627f8>
  t23: ch = br t21, BasicBlock:ch<CF241.preheader 0x58628a8>

The SystemZ target then tries to emit an illegal truncate, as it was not
expecting this for zEC12.

Run with
bin/llc -mtriple=s390x-linux-gnu -mcpu=zEC12

(zEC12 is the previous version, which did not have vector support.)

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