[LLVMbugs] [Bug 9018] New: Documentation of function attributes in a 'call'

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=9018

           Summary: Documentation of function attributes in a 'call'
           Product: Documentation
           Version: 2.8
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: General docs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: llvm at henning-thielemann.de
                CC: llvmbugs at cs.uiuc.edu


http://llvm.org/docs/LangRef.html
says, that the allowed function attributes for 'call' are 'noreturn',
'nounwind', 'readonly' and 'readnone',
but it does not tell how these attributes interact with the ones given in the
according 'declare'.
The description of function attributes says, that function attributes are
attributes of the function - so how can function attributes be part of a
function call?
Is there a difference between

define double @arith(double, double) {
_L1:
  %2 = call double @llvm.sin.f64(double %0)
  %3 = call double @llvm.exp.f64(double %2)
  %4 = fadd double %3, %1
  ret double %4
}

declare double @llvm.sin.f64(double) readnone
declare double @llvm.exp.f64(double) readnone

and

define double @arith(double, double) {
_L1:
  %2 = call double @llvm.sin.f64(double %0) readnone
  %3 = call double @llvm.exp.f64(double %2) readnone
  %4 = fadd double %3, %1
  ret double %4
}

declare double @llvm.sin.f64(double)
declare double @llvm.exp.f64(double)

and

define double @arith(double, double) {
_L1:
  %2 = call double @llvm.sin.f64(double %0) readnone
  %3 = call double @llvm.exp.f64(double %2) readnone
  %4 = fadd double %3, %1
  ret double %4
}

declare double @llvm.sin.f64(double) readnone
declare double @llvm.exp.f64(double) readnone

?
I guess that the union of the sets of attributes of 'declare' and 'call' is
considered when calling a function. If this is true, then the above functions
should be equivalent.

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