[llvm-bugs] [Bug 24789] New: Incorrect codegen for non-standard integer types

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=24789

            Bug ID: 24789
           Summary: Incorrect codegen for non-standard integer types
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: sanjoy at playingwithpointers.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Running

target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

define i1 @f(i32* %ptr) {
 entry:
  %ptr.i10 = bitcast i32* %ptr to i10*
  %val.i10 = load i10, i10* %ptr.i10
  %cmp = icmp eq i10 %val.i10, 77
  ret i1 %cmp
}


through llc -O3 gives

    .text
    .file    "<stdin>"
    .globl    f
    .align    16, 0x90
    .type    f, at function
f:                                      # @f
    .cfi_startproc
# BB#0:                                 # %entry
    movzwl    (%rdi), %eax
    cmpl    $77, %eax
    sete    %al
    retq
.Lfunc_end0:
    .size    f, .Lfunc_end0-f
    .cfi_endproc


    .section    ".note.GNU-stack","", at progbits

I think the right behavior here is to mask out the lower 10 bits from %eax
before comparing it with $77.

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