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8cedcc7579
Summary: After RS4GC, we should drop metadata that is no longer valid. These metadata is used by optimizations scheduled after RS4GC, and can cause a miscompile. One such metadata is invariant.load which is used by LICM sinking transform. After rewriting statepoints, the address of a load maybe relocated. With invariant.load metadata on a load instruction, LICM sinking assumes the loaded value (from a dererenceable address) to be invariant, and rematerializes the load operand and the load at the exit block. This transforms the IR to have an unrelocated use of the address after a statepoint, which is incorrect. Other metadata we conservatively remove are related to dereferenceability and noalias metadata. This patch drops such metadata on store and load instructions after rewriting statepoints. Reviewers: reames, sanjoy, apilipenko Reviewed by: reames Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D33756 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305234 91177308-0d34-0410-b5e6-96231b3b80d8
93 lines
3.5 KiB
LLVM
93 lines
3.5 KiB
LLVM
; RUN: opt -S -rewrite-statepoints-for-gc < %s | FileCheck %s
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; This test checks that metadata that's invalid after RS4GC is dropped.
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; We can miscompile if optimizations scheduled after RS4GC uses the
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; metadata that's infact invalid.
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declare void @bar()
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declare void @baz(i32)
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; Confirm that loadedval instruction does not contain invariant.load metadata.
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; but contains the range metadata.
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; Since loadedval is not marked invariant, it will prevent incorrectly sinking
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; %loadedval in LICM and avoid creation of an unrelocated use of %baseaddr.
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define void @test_invariant_load() gc "statepoint-example" {
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; CHECK-LABEL: @test_invariant_load
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; CHECK: %loadedval = load i32, i32 addrspace(1)* %baseaddr, align 8, !range !0
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bb:
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br label %outerloopHdr
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outerloopHdr: ; preds = %bb6, %bb
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%baseaddr = phi i32 addrspace(1)* [ undef, %bb ], [ %tmp4, %bb6 ]
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; LICM may sink this load to exit block after RS4GC because it's tagged invariant.
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%loadedval = load i32, i32 addrspace(1)* %baseaddr, align 8, !range !0, !invariant.load !1
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br label %innerloopHdr
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innerloopHdr: ; preds = %innerlooplatch, %outerloopHdr
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%tmp4 = phi i32 addrspace(1)* [ %baseaddr, %outerloopHdr ], [ %gep, %innerlooplatch ]
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br label %innermostloophdr
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innermostloophdr: ; preds = %bb6, %innerloopHdr
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br i1 undef, label %exitblock, label %bb6
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bb6: ; preds = %innermostloophdr
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switch i32 undef, label %innermostloophdr [
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i32 0, label %outerloopHdr
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i32 1, label %innerlooplatch
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]
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innerlooplatch: ; preds = %bb6
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call void @bar()
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%gep = getelementptr inbounds i32, i32 addrspace(1)* %tmp4, i64 8
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br label %innerloopHdr
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exitblock: ; preds = %innermostloophdr
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%tmp13 = add i32 42, %loadedval
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call void @baz(i32 %tmp13)
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unreachable
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}
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; drop the noalias metadata.
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define void @test_noalias(i32 %x, i32 addrspace(1)* %p, i32 addrspace(1)* %q) gc "statepoint-example" {
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; CHECK-LABEL: test_noalias
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; CHECK: %y = load i32, i32 addrspace(1)* %q, align 16
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; CHECK: gc.statepoint
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; CHECK: %p.relocated
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; CHECK-NEXT: %p.relocated.casted = bitcast i8 addrspace(1)* %p.relocated to i32 addrspace(1)*
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; CHECK-NEXT: store i32 %x, i32 addrspace(1)* %p.relocated.casted, align 16
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entry:
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%y = load i32, i32 addrspace(1)* %q, align 16, !noalias !3
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call void @baz(i32 %x)
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store i32 %x, i32 addrspace(1)* %p, align 16, !noalias !4
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ret void
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}
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; drop the dereferenceable metadata
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define void @test_dereferenceable(i32 addrspace(1)* addrspace(1)* %p, i32 %x, i32 addrspace(1)* %q) gc "statepoint-example" {
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; CHECK-LABEL: test_dereferenceable
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; CHECK: %v1 = load i32 addrspace(1)*, i32 addrspace(1)* addrspace(1)* %p
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; CHECK-NEXT: %v2 = load i32, i32 addrspace(1)* %v1
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; CHECK: gc.statepoint
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%v1 = load i32 addrspace(1)*, i32 addrspace(1)* addrspace(1)* %p, !dereferenceable !5
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%v2 = load i32, i32 addrspace(1)* %v1
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call void @baz(i32 %x)
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store i32 %v2, i32 addrspace(1)* %q, align 16
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ret void
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}
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declare token @llvm.experimental.gc.statepoint.p0f_isVoidi32f(i64, i32, void (i32)*, i32, i32, ...)
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; Function Attrs: nounwind readonly
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declare i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token, i32, i32) #0
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declare token @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)
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attributes #0 = { nounwind readonly }
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!0 = !{i32 0, i32 2147483647}
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!1 = !{}
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!2 = !{i32 10, i32 1}
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!3 = !{!3}
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!4 = !{!4}
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!5 = !{i64 8}
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