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15017c6fe4
An unreachable default destination can be exploited by other optimizations, and SDag lowering is now prepared to handle them efficiently. For example, branches to the unreachable destination will be optimized away, such as in the case of range checks for switch lookup tables. On 64-bit Linux, this reduces the size of a clang bootstrap by 80 kB (and Chromium by 30 kB). llvm-svn: 223050
95 lines
1.7 KiB
LLVM
95 lines
1.7 KiB
LLVM
; RUN: opt < %s -simplifycfg -S | FileCheck %s
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define void @test1(i1 %C, i1* %BP) {
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; CHECK-LABEL: @test1(
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; CHECK: entry:
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; CHECK-NEXT: ret void
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entry:
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br i1 %C, label %T, label %F
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T:
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store i1 %C, i1* %BP
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unreachable
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F:
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ret void
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}
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define void @test2() {
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; CHECK-LABEL: @test2(
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; CHECK: entry:
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; CHECK-NEXT: call void @test2()
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; CHECK-NEXT: ret void
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entry:
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invoke void @test2( )
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to label %N unwind label %U
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U:
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unreachable
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N:
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ret void
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}
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define i32 @test3(i32 %v) {
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; CHECK-LABEL: @test3(
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; CHECK: entry:
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; CHECK-NEXT: [[CMP:%[A-Za-z0-9]+]] = icmp eq i32 %v, 2
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; CHECK-NEXT: select i1 [[CMP]], i32 2, i32 1
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; CHECK-NEXT: ret
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entry:
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switch i32 %v, label %default [
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i32 1, label %U
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i32 2, label %T
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]
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default:
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ret i32 1
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U:
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unreachable
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T:
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ret i32 2
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}
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;; We can either convert the following control-flow to a select or remove the
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;; unreachable control flow because of the undef store of null. Make sure we do
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;; the latter.
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define void @test5(i1 %cond, i8* %ptr) {
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; CHECK-LABEL: test5
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; CHECK: entry:
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; CHECK-NOT: select
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; CHECK: store i8 2, i8* %ptr
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; CHECK: ret
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entry:
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br i1 %cond, label %bb1, label %bb3
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bb3:
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br label %bb2
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bb1:
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br label %bb2
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bb2:
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%ptr.2 = phi i8* [ %ptr, %bb3 ], [ null, %bb1 ]
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store i8 2, i8* %ptr.2, align 8
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ret void
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}
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; CHECK-LABEL: test6
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; CHECK: entry:
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; CHECK-NOT: select
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; CHECK: store i8 2, i8* %ptr
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; CHECK: ret
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define void @test6(i1 %cond, i8* %ptr) {
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entry:
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br i1 %cond, label %bb1, label %bb2
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bb1:
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br label %bb2
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bb2:
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%ptr.2 = phi i8* [ %ptr, %entry ], [ null, %bb1 ]
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store i8 2, i8* %ptr.2, align 8
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ret void
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}
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