[llvm-bugs] [Bug 31708] New: signext of small integer return types ignored

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=31708

            Bug ID: 31708
           Summary: signext of small integer return types ignored
           Product: new-bugs
           Version: 3.9
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: eric.schweitz at pgroup.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Created attachment 17873
  --> https://llvm.org/bugs/attachment.cgi?id=17873&action=edit
Small test file to show x86 signext i16 returns

In the attached .ll file is a small function that has a return type of "signext
i16". From the LLVM Language Reference, it seems that the value returned ought
to be sign extended to the word width (i32) of the target in this case.

Experimentation showed that sign extension was the case in 3.8.

        movswl  -2(%rsp), %eax

However, in 3.9 the sign extension changed to a zero extension.

        movzwl  -2(%rsp), %eax

This zero extension can be seen in my latest "master" branch build as well.

To reproduce:

  llc -O1 -o bug.s bug.ll

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