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llvm-mirror/test/Transforms/ADCE/2002-05-23-ZeroArgPHITest.ll
David Callahan 86eb682529 [ADCE] Add code to remove dead branches
Summary:
This is last in of a series of patches to evolve ADCE.cpp to support
removing of unnecessary control flow.

This patch adds the code to update the control and data flow graphs
to remove the dead control flow.

Also update unit tests to test the capability to remove dead,
may-be-infinite loop which is enabled by the switch
-adce-remove-loops.

Previous patches:

D23824 [ADCE] Add handling of PHI nodes when removing control flow
D23559 [ADCE] Add control dependence computation
D23225 [ADCE] Modify data structures to support removing control flow
D23065 [ADCE] Refactor anticipating new functionality (NFC)
D23102 [ADCE] Refactoring for new functionality (NFC)

Reviewers: dberlin, majnemer, nadav, mehdi_amini

Subscribers: llvm-commits, david2050, freik, twoh

Differential Revision: https://reviews.llvm.org/D24918

llvm-svn: 289548
2016-12-13 16:42:18 +00:00

36 lines
1.6 KiB
LLVM

; This testcase contains a entire loop that should be removed. The only thing
; left is the store instruction in BB0. The problem this testcase was running
; into was that when the reg109 PHI was getting zero predecessors, it was
; removed even though there were uses still around. Now the uses are filled
; in with a dummy value before the PHI is deleted.
;
; RUN: opt < %s -S -adce | grep bb1
; RUN: opt < %s -S -adce -adce-remove-loops | FileCheck %s
%node_t = type { double*, %node_t*, %node_t**, double**, double*, i32, i32 }
define void @localize_local(%node_t* %nodelist) {
bb0:
%nodelist.upgrd.1 = alloca %node_t* ; <%node_t**> [#uses=2]
store %node_t* %nodelist, %node_t** %nodelist.upgrd.1
br label %bb1
bb1: ; preds = %bb0
%reg107 = load %node_t*, %node_t** %nodelist.upgrd.1 ; <%node_t*> [#uses=2]
%cond211 = icmp eq %node_t* %reg107, null ; <i1> [#uses=1]
; CHECK: br label %bb3
br i1 %cond211, label %bb3, label %bb2
bb2: ; preds = %bb2, %bb1
%reg109 = phi %node_t* [ %reg110, %bb2 ], [ %reg107, %bb1 ] ; <%node_t*> [#uses=1]
%reg212 = getelementptr %node_t, %node_t* %reg109, i64 0, i32 1 ; <%node_t**> [#uses=1]
%reg110 = load %node_t*, %node_t** %reg212 ; <%node_t*> [#uses=2]
%cond213 = icmp ne %node_t* %reg110, null ; <i1> [#uses=1]
; CHECK: br label %bb3
br i1 %cond213, label %bb2, label %bb3
bb3: ; preds = %bb2, %bb1
ret void
}