107 lines
5.1 KiB
LLVM
107 lines
5.1 KiB
LLVM
; RUN: opt -O3 -S < %s | FileCheck --check-prefix=CHECK-OPT %s
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; RUN: llc -verify-machineinstrs < %s | FileCheck --check-prefix=CHECK-LLC %s
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; These tests are targetted at making sure we don't retain information
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; about memory which contains potential gc references across a statepoint.
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; They're carefully written to only outlaw forwarding of references.
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; Depending on the collector, forwarding non-reference fields or
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; constant null references may be perfectly legal. (If unimplemented.)
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; The general structure of these tests is:
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; - learn a fact about memory (via an assume)
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; - cross a statepoint
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; - check the same fact about memory (which we no longer know)
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target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-pc-linux-gnu"
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; If not at a statepoint, we could forward known memory values
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; across this call.
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declare void @func() readonly
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;; Forwarding the value of a pointer load is invalid since it may have
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;; changed at the safepoint. Forwarding a non-gc pointer value would
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;; be valid, but is not currently implemented.
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define i1 @test_load_forward(i32 addrspace(1)* addrspace(1)* %p) gc "statepoint-example" {
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entry:
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%before = load i32 addrspace(1)*, i32 addrspace(1)* addrspace(1)* %p
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%cmp1 = call i1 @f(i32 addrspace(1)* %before)
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call void @llvm.assume(i1 %cmp1)
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%safepoint_token = tail call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* elementtype(void ()) @func, i32 0, i32 0, i32 0, i32 0) ["gc-live" (i32 addrspace(1)* addrspace(1)* %p)]
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%pnew = call i32 addrspace(1)* addrspace(1)* @llvm.experimental.gc.relocate.p1p1i32(token %safepoint_token, i32 0, i32 0)
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%after = load i32 addrspace(1)*, i32 addrspace(1)* addrspace(1)* %pnew
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%cmp2 = call i1 @f(i32 addrspace(1)* %after)
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ret i1 %cmp2
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; CHECK-OPT-LABEL: test_load_forward
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; CHECK-OPT: ret i1 %cmp2
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; CHECK-LLC-LABEL: test_load_forward
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; CHECK-LLC: callq f
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}
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;; Same as above, but forwarding from a store
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define i1 @test_store_forward(i32 addrspace(1)* addrspace(1)* %p,
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i32 addrspace(1)* %v) gc "statepoint-example" {
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entry:
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%cmp1 = call i1 @f(i32 addrspace(1)* %v)
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call void @llvm.assume(i1 %cmp1)
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store i32 addrspace(1)* %v, i32 addrspace(1)* addrspace(1)* %p
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%safepoint_token = tail call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* elementtype(void ()) @func, i32 0, i32 0, i32 0, i32 0) ["gc-live" (i32 addrspace(1)* addrspace(1)* %p)]
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%pnew = call i32 addrspace(1)* addrspace(1)* @llvm.experimental.gc.relocate.p1p1i32(token %safepoint_token, i32 0, i32 0)
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%after = load i32 addrspace(1)*, i32 addrspace(1)* addrspace(1)* %pnew
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%cmp2 = call i1 @f(i32 addrspace(1)* %after)
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ret i1 %cmp2
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; CHECK-OPT-LABEL: test_store_forward
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; CHECK-OPT: ret i1 %cmp2
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; CHECK-LLC-LABEL: test_store_forward
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; CHECK-LLC: callq f
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}
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; A predicate on the pointer which is not simply null, but whose value
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; would be known unchanged if the pointer value could be forwarded.
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; The implementation of such a function could inspect the integral value
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; of the pointer and is thus not safe to reuse after a statepoint.
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declare i1 @f(i32 addrspace(1)* %v) readnone
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; This is a variant of the test_load_forward test which is intended to
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; highlight the fact that a gc pointer can be stored in part of the heap
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; that is not itself GC managed. The GC may have an external mechanism
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; to know about and update that value at a safepoint. Note that the
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; statepoint does not provide the collector with this root.
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define i1 @test_load_forward_nongc_heap(i32 addrspace(1)** %p) gc "statepoint-example" {
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entry:
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%before = load i32 addrspace(1)*, i32 addrspace(1)** %p
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%cmp1 = call i1 @f(i32 addrspace(1)* %before)
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call void @llvm.assume(i1 %cmp1)
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call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* elementtype(void ()) @func, i32 0, i32 0, i32 0, i32 0)
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%after = load i32 addrspace(1)*, i32 addrspace(1)** %p
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%cmp2 = call i1 @f(i32 addrspace(1)* %after)
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ret i1 %cmp2
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; CHECK-OPT-LABEL: test_load_forward_nongc_heap
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; CHECK-OPT: ret i1 %cmp2
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; CHECK-LLC-LABEL: test_load_forward_nongc_heap
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; CHECK-LLC: callq f
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}
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;; Same as above, but forwarding from a store
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define i1 @test_store_forward_nongc_heap(i32 addrspace(1)** %p,
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i32 addrspace(1)* %v) gc "statepoint-example" {
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entry:
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%cmp1 = call i1 @f(i32 addrspace(1)* %v)
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call void @llvm.assume(i1 %cmp1)
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store i32 addrspace(1)* %v, i32 addrspace(1)** %p
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call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* elementtype(void ()) @func, i32 0, i32 0, i32 0, i32 0)
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%after = load i32 addrspace(1)*, i32 addrspace(1)** %p
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%cmp2 = call i1 @f(i32 addrspace(1)* %after)
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ret i1 %cmp2
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; CHECK-OPT-LABEL: test_store_forward_nongc_heap
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; CHECK-OPT: ret i1 %cmp2
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; CHECK-LLC-LABEL: test_store_forward_nongc_heap
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; CHECK-LLC: callq f
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}
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declare void @llvm.assume(i1)
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declare token @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)
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declare i32 addrspace(1)* addrspace(1)* @llvm.experimental.gc.relocate.p1p1i32(token, i32, i32) #3
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