forked from OSchip/llvm-project
Semantic tests for memory invalidation at statepoints
These are simply a collection of tests intended to show that information about the contents of gc references in the heap is lost at a statepoint. I've tried to write them so that they don't disallow correct transformations, while still being fairly easy to understand. p.s. Ideas for additional tests are welcome. Differential Revision: http://reviews.llvm.org/D6491 llvm-svn: 224971
This commit is contained in:
Philip Reames
parent
608a24501c
commit
5909ebcd6c
|
|
@ -0,0 +1,108 @@
|
|||
; RUN: opt -O3 -S < %s | FileCheck --check-prefix=CHECK-OPT %s
|
||||
; RUN: llc < %s | FileCheck --check-prefix=CHECK-LLC %s
|
||||
; These tests are targetted at making sure we don't retain information
|
||||
; about memory which contains potential gc references across a statepoint.
|
||||
; They're carefully written to only outlaw forwarding of references.
|
||||
; Depending on the collector, forwarding non-reference fields or
|
||||
; constant null references may be perfectly legal. (If unimplemented.)
|
||||
; The general structure of these tests is:
|
||||
; - learn a fact about memory (via an assume)
|
||||
; - cross a statepoint
|
||||
; - check the same fact about memory (which we no longer know)
|
||||
|
||||
target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
|
||||
target triple = "x86_64-pc-linux-gnu"
|
||||
|
||||
; If not at a statepoint, we could forward known memory values
|
||||
; across this call.
|
||||
declare void @func() readonly
|
||||
|
||||
;; Forwarding the value of a pointer load is invalid since it may have
|
||||
;; changed at the safepoint. Forwarding a non-gc pointer value would
|
||||
;; be valid, but is not currently implemented.
|
||||
define i1 @test_load_forward(i32 addrspace(1)* addrspace(1)* %p) {
|
||||
entry:
|
||||
%before = load i32 addrspace(1)* addrspace(1)* %p
|
||||
%cmp1 = call i1 @f(i32 addrspace(1)* %before)
|
||||
call void @llvm.assume(i1 %cmp1)
|
||||
%safepoint_token = tail call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0, i32 addrspace(1)* addrspace(1)* %p)
|
||||
%pnew = call i32 addrspace(1)* addrspace(1)* @llvm.experimental.gc.relocate.p1p1i32(i32 %safepoint_token, i32 4, i32 4)
|
||||
%after = load i32 addrspace(1)* addrspace(1)* %pnew
|
||||
%cmp2 = call i1 @f(i32 addrspace(1)* %after)
|
||||
ret i1 %cmp2
|
||||
|
||||
; CHECK-OPT-LABEL: test_load_forward
|
||||
; CHECK-OPT: ret i1 %cmp2
|
||||
; CHECK-LLC-LABEL: test_load_forward
|
||||
; CHECK-LLC: callq f
|
||||
}
|
||||
|
||||
;; Same as above, but forwarding from a store
|
||||
define i1 @test_store_forward(i32 addrspace(1)* addrspace(1)* %p,
|
||||
i32 addrspace(1)* %v) {
|
||||
entry:
|
||||
%cmp1 = call i1 @f(i32 addrspace(1)* %v)
|
||||
call void @llvm.assume(i1 %cmp1)
|
||||
store i32 addrspace(1)* %v, i32 addrspace(1)* addrspace(1)* %p
|
||||
%safepoint_token = tail call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0, i32 addrspace(1)* addrspace(1)* %p)
|
||||
%pnew = call i32 addrspace(1)* addrspace(1)* @llvm.experimental.gc.relocate.p1p1i32(i32 %safepoint_token, i32 4, i32 4)
|
||||
%after = load i32 addrspace(1)* addrspace(1)* %pnew
|
||||
%cmp2 = call i1 @f(i32 addrspace(1)* %after)
|
||||
ret i1 %cmp2
|
||||
|
||||
; CHECK-OPT-LABEL: test_store_forward
|
||||
; CHECK-OPT: ret i1 %cmp2
|
||||
; CHECK-LLC-LABEL: test_store_forward
|
||||
; CHECK-LLC: callq f
|
||||
}
|
||||
|
||||
; A predicate on the pointer which is not simply null, but whose value
|
||||
; would be known unchanged if the pointer value could be forwarded.
|
||||
; The implementation of such a function could inspect the integral value
|
||||
; of the pointer and is thus not safe to reuse after a statepoint.
|
||||
declare i1 @f(i32 addrspace(1)* %v) readnone
|
||||
|
||||
; This is a variant of the test_load_forward test which is intended to
|
||||
; highlight the fact that a gc pointer can be stored in part of the heap
|
||||
; that is not itself GC managed. The GC may have an external mechanism
|
||||
; to know about and update that value at a safepoint. Note that the
|
||||
; statepoint does not provide the collector with this root.
|
||||
define i1 @test_load_forward_nongc_heap(i32 addrspace(1)** %p) {
|
||||
entry:
|
||||
%before = load i32 addrspace(1)** %p
|
||||
%cmp1 = call i1 @f(i32 addrspace(1)* %before)
|
||||
call void @llvm.assume(i1 %cmp1)
|
||||
call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0)
|
||||
%after = load i32 addrspace(1)** %p
|
||||
%cmp2 = call i1 @f(i32 addrspace(1)* %after)
|
||||
ret i1 %cmp2
|
||||
|
||||
; CHECK-OPT-LABEL: test_load_forward_nongc_heap
|
||||
; CHECK-OPT: ret i1 %cmp2
|
||||
; CHECK-LLC-LABEL: test_load_forward_nongc_heap
|
||||
; CHECK-LLC: callq f
|
||||
}
|
||||
|
||||
;; Same as above, but forwarding from a store
|
||||
define i1 @test_store_forward_nongc_heap(i32 addrspace(1)** %p,
|
||||
i32 addrspace(1)* %v) {
|
||||
entry:
|
||||
%cmp1 = call i1 @f(i32 addrspace(1)* %v)
|
||||
call void @llvm.assume(i1 %cmp1)
|
||||
store i32 addrspace(1)* %v, i32 addrspace(1)** %p
|
||||
call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0)
|
||||
%after = load i32 addrspace(1)** %p
|
||||
%cmp2 = call i1 @f(i32 addrspace(1)* %after)
|
||||
ret i1 %cmp2
|
||||
|
||||
; CHECK-OPT-LABEL: test_store_forward_nongc_heap
|
||||
; CHECK-OPT: ret i1 %cmp2
|
||||
; CHECK-LLC-LABEL: test_store_forward_nongc_heap
|
||||
; CHECK-LLC: callq f
|
||||
}
|
||||
|
||||
|
||||
declare void @llvm.assume(i1)
|
||||
declare i32 @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()*, i32, i32, ...)
|
||||
declare i32 addrspace(1)* addrspace(1)* @llvm.experimental.gc.relocate.p1p1i32(i32, i32, i32) #3
|
||||
|
||||
Loading…
Reference in New Issue