Ramkumar Ramachandra 0608cec657 InstCombine: propagate deref via new addDereferenceableAttr
The "dereferenceable" attribute cannot be added via .addAttribute(),
since it also expects a size in bytes. AttrBuilder#addAttribute or
AttributeSet#addAttribute is wrapped by classes Function, InvokeInst,
and CallInst. Add corresponding wrappers to
AttrBuilder#addDereferenceableAttr.

Having done this, propagate the dereferenceable attribute via
gc.relocate, adding a test to exercise it. Note that -datalayout is
required during execution over and above -instcombine, because
InstCombine only optionally requires DataLayoutPass.

Differential Revision: http://reviews.llvm.org/D7510

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229265 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-14 19:37:54 +00:00

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LLVM

; RUN: opt < %s -datalayout -instcombine -S | FileCheck %s
; Uses InstCombine with DataLayout to propagate dereferenceable
; attribute via gc.relocate: if the derived ptr is dereferenceable(N),
; then the return attribute of gc.relocate is dereferenceable(N).
declare zeroext i1 @return_i1()
declare i32 @llvm.experimental.gc.statepoint.p0f_i1f(i1 ()*, i32, i32, ...)
declare i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32, i32, i32)
define i32 addrspace(1)* @deref(i32 addrspace(1)* dereferenceable(8) %dparam) {
; Checks that a dereferenceabler pointer
; CHECK-LABEL: @deref
; CHECK: call dereferenceable(8)
entry:
%load = load i32 addrspace(1)* %dparam
%tok = tail call i32 (i1 ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_i1f(i1 ()* @return_i1, i32 0, i32 0, i32 0, i32 addrspace(1)* %dparam)
%relocate = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %tok, i32 4, i32 4)
ret i32 addrspace(1)* %relocate
}