40 lines
1.2 KiB
LLVM
40 lines
1.2 KiB
LLVM
; RUN: opt -early-cse -S %s | FileCheck %s
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%mystruct = type { i32 }
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; @var is global so that *every* GEP argument is Constant.
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@var = external global %mystruct
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; Control flow is to make the dominance tree consider the final icmp before it
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; gets to simplify the purely constant one (%tst). Since that icmp uses the
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; select that gets considered next. Finally the select simplification looks at
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; the %tst icmp and we don't want it to speculate about what happens if "i32 0"
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; is actually "i32 1", broken universes are automatic UB.
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;
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; In this case doing the speculation would create an invalid GEP(@var, 0, 1) and
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; crash.
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define i1 @test_constant_speculation() {
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; CHECK-LABEL: define i1 @test_constant_speculation
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entry:
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br i1 undef, label %end, label %select
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select:
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; CHECK: select:
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; CHECK-NOT: icmp
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; CHECK-NOT: getelementptr
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; CHECK-NOT: select
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%tst = icmp eq i32 1, 0
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%elt = getelementptr %mystruct, %mystruct* @var, i64 0, i32 0
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%sel = select i1 %tst, i32* null, i32* %elt
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br label %end
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end:
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; CHECK: end:
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; CHECK: %tmp = phi i32* [ null, %entry ], [ getelementptr inbounds (%mystruct, %mystruct* @var, i64 0, i32 0), %select ]
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%tmp = phi i32* [null, %entry], [%sel, %select]
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%res = icmp eq i32* %tmp, null
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ret i1 %res
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}
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