@capn -- Could you please look into this issue. 
Assigning this issue to you, as per the update we received from you in the  Issue 781505 . Please reassign if it not related to your changes.
Thanks.

ClusterFuzz has detected this issue as fixed in range 521492:521536.

Detailed report: https://clusterfuzz.com/testcase?key=6370861975339008

Fuzzer: libFuzzer_swiftshader_vertex_routine_fuzzer
Job Type: libfuzzer_chrome_ubsan
Platform Id: linux

Crash Type: Null-dereference READ
Crash Address: 0x000000000000
Crash State:
  Ice::Operand::getKind
  Ice::Constant::classof
  Ice::Cfg::floatConstantCSE
  
Sanitizer: undefined (UBSAN)

Regressed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_ubsan&range=512956:512987
Fixed: https://clusterfuzz.com/revisions?job=libfuzzer_chrome_ubsan&range=521492:521536

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6370861975339008

See https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/reference.md for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

ClusterFuzz testcase 6370861975339008 is verified as fixed, so closing issue as verified.

If this is incorrect, please add ClusterFuzz-Wrong label and re-open the issue.