[LLVMbugs] [Bug 19975] New: loop vectorizer miscompile

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=19975

            Bug ID: 19975
           Summary: loop vectorizer miscompile
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: Loop Optimizer
          Assignee: unassignedbugs at nondot.org
          Reporter: nicholas at mxc.ca
                CC: aschwaighofer at apple.com, llvmbugs at cs.uiuc.edu
    Classification: Unclassified

Testcase:

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

@fmt = constant [4 x i8] c"%d\0A\00"

declare i32 @printf(i8*, ...)

define i32 @main() {
entry:
  br label %while.body

while.body:                                       ; preds = %if.end3, %entry
  %i.0 = phi i32 [ 0, %entry ], [ %inc, %if.end3 ]
  %count.0 = phi i32 [ 1, %entry ], [ %add.count.0, %if.end3 ]
  %cmp = icmp ult i32 %i.0, 5
  %add = zext i1 %cmp to i32
  %add.count.0 = add i32 %count.0, %add
  %cmp1 = icmp eq i32 %i.0, -1
  br i1 %cmp1, label %while.end, label %if.end3

if.end3:                                          ; preds = %while.body
  %inc = add i32 %i.0, 1
  br label %while.body

while.end:                                        ; preds = %while.body
  %0 = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([4 x i8]* @fmt,
i64 0, i64 0), i32 %add.count.0) #1
  ret i32 %add.count.0
}

The output and exit code are '6'. Run with "opt -loop-vectorize" then the
output and exit code are '1'.

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