[LLVMbugs] [Bug 2358] New: SCCP incorrectly folds cttz(undef) to undef

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=2358

           Summary: SCCP incorrectly folds cttz(undef) to undef
           Product: new-bugs
           Version: unspecified
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: sharparrow1 at yahoo.com
                CC: llvmbugs at cs.uiuc.edu


Testcase:

target datalayout =
"e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i686-pc-linux-gnu"

define i32 @x(i32 %b) {
entry:
  %val = call i32 @llvm.cttz.i32(i32 undef)
  ret i32 %val
}

declare i32 @llvm.cttz.i32(i32)

SCCP folds x to ret i32 undef; this is wrong because all of the bits except for
the bottom 6 must be zero.


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