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[SimplifyCFG] add test for part of PR34471 (switch squashing); NFC 

llvm-svn: 316008
This commit is contained in:
Sanjay Patel 2017-10-17 15:56:42 +00:00
parent a5be48b3e0
commit 6d172f2d72
1 changed files with 43 additions and 0 deletions
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43
llvm/test/Transforms/SimplifyCFG/ForwardSwitchConditionToPHI.ll
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@ -41,3 +41,46 @@ return: ; preds = %entry, %sw.bb4, %sw
ret i32 %retval.0
}
; If 1 incoming phi value is a case constant of a switch, convert it to the switch condition:
; https://bugs.llvm.org/show_bug.cgi?id=34471
; This then subsequently should allow squashing of the other trivial case blocks.
define i32 @PR34471(i32 %x) {
; CHECK-LABEL: @PR34471(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[X:%.*]], label [[ELSE3:%.*]] [
; CHECK-NEXT: i32 17, label [[RETURN:%.*]]
; CHECK-NEXT: i32 19, label [[IF19:%.*]]
; CHECK-NEXT: i32 42, label [[IF42:%.*]]
; CHECK-NEXT: ]
; CHECK: if19:
; CHECK-NEXT: br label [[RETURN]]
; CHECK: if42:
; CHECK-NEXT: br label [[RETURN]]
; CHECK: else3:
; CHECK-NEXT: br label [[RETURN]]
; CHECK: return:
; CHECK-NEXT: [[R:%.*]] = phi i32 [ [[X]], [[IF19]] ], [ [[X]], [[IF42]] ], [ 0, [[ELSE3]] ], [ 17, [[ENTRY:%.*]] ]
; CHECK-NEXT: ret i32 [[R]]
;
entry:
switch i32 %x, label %else3 [
i32 17, label %return
i32 19, label %if19
i32 42, label %if42
]
if19:
br label %return
if42:
br label %return
else3:
br label %return
return:
%r = phi i32 [ %x, %if19 ], [ %x, %if42 ], [ 0, %else3 ], [ 17, %entry ]
ret i32 %r
}