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llvm-mirror/test/SafepointIRVerifier/compares.ll
Anna Thomas 7b53bd9054 [SafepointIRVerifier] Avoid false positives in GC verifier for compare between pointers
Today the safepoint IR verifier catches some unrelocated uses of base
pointers that are actually valid.

With this change, we narrow down the set of false positives.
Specifically, the verifier knows about compares to null and compares
between 2 unrelocated pointers.

Reviewed by: skatkov

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D35057

llvm-svn: 307392
2017-07-07 13:02:29 +00:00

86 lines
4.8 KiB
LLVM

; RUN: opt -safepoint-ir-verifier-print-only -verify-safepoint-ir -S %s 2>&1 | FileCheck %s
; In some cases, it is valid to have unrelocated pointers used as compare
; operands. Make sure the verifier knows to spot these exceptions.
; comparison against null.
define i8 addrspace(1)* @test1(i64 %arg, i8 addrspace(1)* %addr) gc "statepoint-example" {
; CHECK: No illegal uses found by SafepointIRVerifier in: test1
entry:
%load_addr = getelementptr i8, i8 addrspace(1)* %addr, i64 %arg
%safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
%cmp = icmp eq i8 addrspace(1)* %load_addr, null
ret i8 addrspace(1)* null
}
; comparison against exclusively derived null.
define void @test2(i64 %arg, i1 %cond, i8 addrspace(1)* %addr) gc "statepoint-example" {
; CHECK: No illegal uses found by SafepointIRVerifier in: test2
%load_addr = getelementptr i8, i8 addrspace(1)* null, i64 %arg
%load_addr_sel = select i1 %cond, i8 addrspace(1)* null, i8 addrspace(1)* %load_addr
%safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
%cmp = icmp eq i8 addrspace(1)* %addr, %load_addr_sel
ret void
}
; comparison against a constant non-null pointer. This is unrelocated use, since
; that pointer bits may mean something in a VM.
define void @test3(i64 %arg, i32 addrspace(1)* %addr) gc "statepoint-example" {
; CHECK-LABEL: Verifying gc pointers in function: test3
; CHECK: Illegal use of unrelocated value found!
entry:
%load_addr = getelementptr i32, i32 addrspace(1)* %addr, i64 %arg
%load_addr_const = getelementptr i32, i32 addrspace(1)* inttoptr (i64 15 to i32 addrspace(1)*), i64 %arg
%safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
%cmp = icmp eq i32 addrspace(1)* %load_addr, %load_addr_const
ret void
}
; comparison against a derived pointer that is *not* exclusively derived from
; null. An unrelocated use since the derived pointer could be from the constant
; non-null pointer (load_addr.2).
define void @test4(i64 %arg, i1 %cond, i8 addrspace(1)* %base) gc "statepoint-example" {
; CHECK-LABEL: Verifying gc pointers in function: test4
; CHECK: Illegal use of unrelocated value found!
entry:
%load_addr.1 = getelementptr i8, i8 addrspace(1)* null, i64 %arg
br i1 %cond, label %split, label %join
split:
%load_addr.2 = getelementptr i8, i8 addrspace(1)* inttoptr (i64 30 to i8 addrspace(1)*), i64 %arg
br label %join
join:
%load_addr = phi i8 addrspace(1)* [%load_addr.1, %entry], [%load_addr.2, %split]
%safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
%cmp = icmp eq i8 addrspace(1)* %load_addr, %base
ret void
}
; comparison between 2 unrelocated base pointers.
; Since the cmp can be reordered legally before the safepoint, these are correct
; unrelocated uses of the pointers.
define void @test5(i64 %arg, i8 addrspace(1)* %base1, i8 addrspace(1)* %base2) gc "statepoint-example" {
; CHECK: No illegal uses found by SafepointIRVerifier in: test5
%load_addr1 = getelementptr i8, i8 addrspace(1)* %base1, i64 %arg
%load_addr2 = getelementptr i8, i8 addrspace(1)* %base2, i64 %arg
%safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
%cmp = icmp eq i8 addrspace(1)* %load_addr1, %load_addr2
ret void
}
; comparison between a relocated and an unrelocated pointer.
; this is invalid use of the unrelocated pointer.
define void @test6(i64 %arg, i8 addrspace(1)* %base1, i8 addrspace(1)* %base2) gc "statepoint-example" {
; CHECK-LABEL: Verifying gc pointers in function: test6
; CHECK: Illegal use of unrelocated value found!
%load_addr1 = getelementptr i8, i8 addrspace(1)* %base1, i64 %arg
%safepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* undef, i32 0, i32 0, i32 0, i32 0, i8 addrspace(1)* %base2 , i32 -1, i32 0, i32 0, i32 0)
%ptr2.relocated = call i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token %safepoint_token, i32 7, i32 7) ; base2, base2
%cmp = icmp eq i8 addrspace(1)* %load_addr1, %ptr2.relocated
ret void
}
declare token @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)
declare i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token, i32, i32)