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95ac2d26ea
As shown by the included test case, it's reasonable to end up with constant references during base pointer calculation. The code actually handled this case just fine, we only had the assert to help isolate problems under the belief that constant references shouldn't be present in IR generated by managed frontends. This turned out to be wrong on two fronts: 1) Manual Jacobs is working on a language with constant references, and b) we found a case where the optimizer does create them in practice. llvm-svn: 256079
96 lines
3.5 KiB
LLVM
96 lines
3.5 KiB
LLVM
; RUN: opt -S -rewrite-statepoints-for-gc %s | FileCheck %s
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declare void @foo()
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declare i32 @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)
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; constants don't get relocated.
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define i8 @test() gc "statepoint-example" {
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; CHECK-LABEL: @test
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; CHECK: gc.statepoint
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; CHECK-NEXT: load i8, i8 addrspace(1)* inttoptr (i64 15 to i8 addrspace(1)*)
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entry:
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call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @foo, i32 0, i32 0, i32 0, i32 0)
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%res = load i8, i8 addrspace(1)* inttoptr (i64 15 to i8 addrspace(1)*)
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ret i8 %res
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}
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; Mostly just here to show reasonable code test can come from.
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define i8 @test2(i8 addrspace(1)* %p) gc "statepoint-example" {
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; CHECK-LABEL: @test2
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; CHECK: gc.statepoint
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; CHECK-NEXT: gc.relocate
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; CHECK-NEXT: icmp
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entry:
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call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @foo, i32 0, i32 0, i32 0, i32 0)
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%cmp = icmp eq i8 addrspace(1)* %p, null
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br i1 %cmp, label %taken, label %not_taken
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taken:
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ret i8 0
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not_taken:
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%cmp2 = icmp ne i8 addrspace(1)* %p, null
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br i1 %cmp2, label %taken, label %dead
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dead:
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; We see that dead can't be reached, but the optimizer might not. It's
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; completely legal for it to exploit the fact that if dead executed, %p
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; would have to equal null. This can produce intermediate states which
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; look like that of test above, even if arbitrary constant addresses aren't
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; legal in the source language
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%addr = getelementptr i8, i8 addrspace(1)* %p, i32 15
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%res = load i8, i8addrspace(1)* %addr
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ret i8 %res
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}
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@G = addrspace(1) global i8 5
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; Globals don't move and thus don't get relocated
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define i8 @test3(i1 %always_true) gc "statepoint-example" {
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; CHECK-LABEL: @test3
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; CHECK: gc.statepoint
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; CHECK-NEXT: load i8, i8 addrspace(1)* @G
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entry:
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call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @foo, i32 0, i32 0, i32 0, i32 0)
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%res = load i8, i8 addrspace(1)* @G, align 1
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ret i8 %res
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}
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; Even for source languages without constant references, we can
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; see constants can show up along paths where the value is dead.
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; This is particular relevant when computing bases of PHIs.
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define i8 addrspace(1)* @test4(i8 addrspace(1)* %p) gc "statepoint-example" {
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; CHECK-LABEL: @test4
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entry:
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%is_null = icmp eq i8 addrspace(1)* %p, null
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br i1 %is_null, label %split, label %join
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split:
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call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @foo, i32 0, i32 0, i32 0, i32 0)
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%arg_value_addr.i = getelementptr inbounds i8, i8 addrspace(1)* %p, i64 8
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%arg_value_addr_casted.i = bitcast i8 addrspace(1)* %arg_value_addr.i to i8 addrspace(1)* addrspace(1)*
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br label %join
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join:
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; CHECK-LABEL: join
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; CHECK: %addr2.base =
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%addr2 = phi i8 addrspace(1)* addrspace(1)* [ %arg_value_addr_casted.i, %split ], [ inttoptr (i64 8 to i8 addrspace(1)* addrspace(1)*), %entry ]
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;; NOTE: This particular example can be jump-threaded, but in general,
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;; we can't, and have to deal with the resulting IR.
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br i1 %is_null, label %early-exit, label %use
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early-exit:
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ret i8 addrspace(1)* null
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use:
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; CHECK-LABEL: use:
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; CHECK: gc.statepoint
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; CHECK: gc.relocate
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call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @foo, i32 0, i32 0, i32 0, i32 0)
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%res = load i8 addrspace(1)*, i8 addrspace(1)* addrspace(1)* %addr2, align 1
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ret i8 addrspace(1)* %res
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}
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