98a2dabc08
As Sanjoy pointed out over in http://reviews.llvm.org/D11819, a switch on an icmp should always be able to become a branch instruction. This patch generalizes that notion slightly to prove that the default case of a switch is unreachable if the cases completely cover all possible bit patterns in the condition. Once that's done, the switch to branch conversion kicks in just fine. Note: Duplicate case values are disallowed by the LangRef and verifier. Differential Revision: http://reviews.llvm.org/D11995 llvm-svn: 246125
88 lines
1.8 KiB
LLVM
88 lines
1.8 KiB
LLVM
; RUN: opt %s -S -simplifycfg | FileCheck %s
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declare void @foo(i32)
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define void @test(i1 %a) {
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; CHECK-LABEL @test
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; CHECK: br i1 [[IGNORE:%.*]], label %true, label %false
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switch i1 %a, label %default [i1 1, label %true
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i1 0, label %false]
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true:
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call void @foo(i32 1)
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ret void
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false:
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call void @foo(i32 3)
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ret void
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default:
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call void @foo(i32 2)
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ret void
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}
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define void @test2(i2 %a) {
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; CHECK-LABEL @test2
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switch i2 %a, label %default [i2 0, label %case0
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i2 1, label %case1
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i2 2, label %case2
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i2 3, label %case3]
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case0:
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call void @foo(i32 0)
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ret void
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case1:
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call void @foo(i32 1)
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ret void
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case2:
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call void @foo(i32 2)
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ret void
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case3:
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call void @foo(i32 3)
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ret void
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default:
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; CHECK-LABEL: default1:
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; CHECK-NEXT: unreachable
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call void @foo(i32 4)
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ret void
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}
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; This one is a negative test - we know the value of the default,
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; but that's about it
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define void @test3(i2 %a) {
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; CHECK-LABEL @test3
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switch i2 %a, label %default [i2 0, label %case0
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i2 1, label %case1
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i2 2, label %case2]
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case0:
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call void @foo(i32 0)
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ret void
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case1:
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call void @foo(i32 1)
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ret void
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case2:
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call void @foo(i32 2)
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ret void
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default:
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; CHECK-LABEL: default:
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; CHECK-NEXT: call void @foo
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call void @foo(i32 0)
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ret void
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}
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; Negative test - check for possible overflow when computing
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; number of possible cases.
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define void @test4(i128 %a) {
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; CHECK-LABEL @test4
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switch i128 %a, label %default [i128 0, label %case0
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i128 1, label %case1]
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case0:
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call void @foo(i32 0)
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ret void
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case1:
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call void @foo(i32 1)
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ret void
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default:
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; CHECK-LABEL: default:
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; CHECK-NEXT: call void @foo
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call void @foo(i32 0)
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ret void
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}
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