[llvm-bugs] [Bug 32485] New: Invalid PPC CTR loop with 128bit integers

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=32485

            Bug ID: 32485
           Summary: Invalid PPC CTR loop with 128bit integers
           Product: libraries
           Version: 4.0
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: PowerPC
          Assignee: unassignedbugs at nondot.org
          Reporter: mail at timnn.me
                CC: llvm-bugs at lists.llvm.org

Compiling the below IR with llc -O1 (Debug Assertions enabled, affects at least
LLVM 4.0 & Master) triggers an unreachable:

```
Invalid PPC CTR loop!
UNREACHABLE executed at
/home/logic/build-tmp/llvm-master/src/lib/Target/PowerPC/PPCCTRLoops.cpp:722!

[...]

0.      Program arguments: ../../../../../llvm-master/build/bin/llc -O1
core.red-4.ll
1.      Running pass 'Function Pass Manager' on module 'core.red-4.ll'.
2.      Running pass 'PowerPC CTR Loops Verify' on function '@_Crash_Fn'
```

IR:

```
; ModuleID = 'bugpoint-reduced-simplified.bc'
source_filename = "bugpoint-output-7eb0c3b.bc"
target datalayout = "E-m:e-i64:64-n32:64"
target triple = "powerpc64-unknown-linux-gnu"

; Function Attrs: uwtable
define fastcc void @_Crash_Fn() unnamed_addr #0 {
entry-block:
  br label %_Label_0

_Label_0:                                         ; preds = %_Label_0,
%entry-block
  %result.0138 = phi i128 [ %5, %_Label_0 ], [ 0, %entry-block ]
  %iter.sroa.0.0137 = phi i8* [ %0, %_Label_0 ], [ undef, %entry-block ]
  %0 = getelementptr inbounds i8, i8* %iter.sroa.0.0137, i64 1
  %1 = tail call { i128, i1 } @llvm.smul.with.overflow.i128(i128 %result.0138,
i128 undef) #2
  %2 = extractvalue { i128, i1 } %1, 0
  %3 = tail call { i128, i1 } @llvm.sadd.with.overflow.i128(i128 %2, i128 0) #2
  %4 = extractvalue { i128, i1 } %3, 1
  %5 = extractvalue { i128, i1 } %3, 0
  %6 = icmp eq i8* %0, null
  br i1 %6, label %bb66.loopexit, label %_Label_0

bb66.loopexit:                                    ; preds = %_Label_0
  unreachable
}

; Function Attrs: nounwind readnone
declare { i128, i1 } @llvm.sadd.with.overflow.i128(i128, i128) #1

; Function Attrs: nounwind readnone
declare { i128, i1 } @llvm.smul.with.overflow.i128(i128, i128) #1

attributes #0 = { uwtable }
attributes #1 = { nounwind readnone }
attributes #2 = { nounwind }
```

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