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llvm-mirror/test/Transforms/ADCE/2003-04-25-PHIPostDominateProblem.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

38 lines
1.1 KiB
LLVM

; THis testcase caused an assertion failure because a PHI node did not have
; entries for it's postdominator. But I think this can only happen when the
; PHI node is dead, so we just avoid patching up dead PHI nodes.
; RUN: opt < %s -adce -S | FileCheck %s
; RUN: opt < %s -adce -adce-remove-loops -S | FileCheck %s
target datalayout = "e-p:32:32"
define void @dead_test8() {
entry:
br label %loopentry
loopentry: ; preds = %endif, %entry
%k.1 = phi i32 [ %k.0, %endif ], [ 0, %entry ] ; <i32> [#uses=1]
br i1 false, label %no_exit, label %return
no_exit: ; preds = %loopentry
; CHECK: br label %then
br i1 false, label %then, label %else
then: ; preds = %no_exit
br label %endif
else: ; preds = %no_exit
%dec = add i32 %k.1, -1 ; <i32> [#uses=1]
br label %endif
endif: ; preds = %else, %then
%k.0 = phi i32 [ %dec, %else ], [ 0, %then ] ; <i32> [#uses=1]
store i32 2, i32* null
br label %loopentry
return: ; preds = %loopentry
ret void
}