RPCS3/llvm
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm.git synced 2024-12-03 01:12:53 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Make llvm.objectsize more conservative with null

Browse Source 
In non-zero address spaces, we were reporting that an object at `null`
always occupies zero bytes. This is incorrect in many cases, so just
return `unknown` in those cases for now.

Differential Revision: https://reviews.llvm.org/D48860


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@336611 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
George Burgess IV 2018-07-09 22:21:16 +00:00
parent ae0f1dc928
commit 401e29e8b7
4 changed files with 35 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
docs/LangRef.rst
View File

@ -14459,10 +14459,10 @@ The ``llvm.objectsize`` intrinsic takes three arguments. The first argument is
a pointer to or into the ``object``. The second argument determines whether
``llvm.objectsize`` returns 0 (if true) or -1 (if false) when the object size
is unknown. The third argument controls how ``llvm.objectsize`` acts when
``null`` is used as its pointer argument. If it's true and the pointer is in
address space 0, ``null`` is treated as an opaque value with an unknown number
of bytes. Otherwise, ``llvm.objectsize`` reports 0 bytes available when given
``null``.
``null`` in address space 0 is used as its pointer argument. If it's ``false``,
``llvm.objectsize`` reports 0 bytes available when given ``null``. Otherwise, if
the ``null`` is in a non-zero address space or if ``true`` is given for the
third argument of ``llvm.objectsize``, we assume its size is unknown.
The second and third arguments only accept constants.

9
lib/Analysis/MemoryBuiltins.cpp
View File

@ -642,7 +642,14 @@ SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) {
SizeOffsetType
ObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull& CPN) {
if (Options.NullIsUnknownSize && CPN.getType()->getAddressSpace() == 0)
// If null is unknown, there's nothing we can do. Additionally, non-zero
// address spaces can make use of null, so we don't presume to know anything
// about that.
//
// TODO: How should this work with address space casts? We currently just drop
// them on the floor, but it's unclear what we should do when a NULL from
// addrspace(1) gets casted to addrspace(0) (or vice-versa).
if (Options.NullIsUnknownSize || CPN.getType()->getAddressSpace())
return unknown();
return std::make_pair(Zero, Zero);
}

20
test/Transforms/CodeGenPrepare/basic.ll
View File

@ -46,7 +46,7 @@ entry:
; CHECK-LABEL: @test_objectsize_null_flag_noas0(
define i64 @test_objectsize_null_flag_noas0() {
entry:
; CHECK: ret i64 0
; CHECK: ret i64 -1
%0 = tail call i64 @llvm.objectsize.i64.p1i8(i8 addrspace(1)* null, i1 false,
i1 true)
ret i64 %0
@ -61,6 +61,24 @@ entry:
ret i64 %0
}
; CHECK-LABEL: @test_objectsize_null_known_flag_noas0
define i64 @test_objectsize_null_known_flag_noas0() {
entry:
; CHECK: ret i64 -1
%0 = tail call i64 @llvm.objectsize.i64.p1i8(i8 addrspace(1)* null, i1 false,
i1 false)
ret i64 %0
}
; CHECK-LABEL: @test_objectsize_null_known_flag_min_noas0
define i64 @test_objectsize_null_known_flag_min_noas0() {
entry:
; CHECK: ret i64 0
%0 = tail call i64 @llvm.objectsize.i64.p1i8(i8 addrspace(1)* null, i1 true,
i1 false)
ret i64 %0
}
declare i64 @llvm.objectsize.i64(i8*, i1, i1) nounwind readonly
declare i64 @llvm.objectsize.i64.p1i8(i8 addrspace(1)*, i1, i1) nounwind readonly

8
test/Transforms/InstCombine/objsize.ll
View File

@ -271,7 +271,7 @@ define i32 @test23() {
; 1 is an arbitrary non-zero address space.
; CHECK-LABEL: @test24(
; CHECK: ret i32 0
; CHECK: llvm.objectsize
define i32 @test24() {
%1 = call i32 @llvm.objectsize.i32.p1i8(i8 addrspace(1)* null, i1 false,
i1 false)
@ -279,7 +279,7 @@ define i32 @test24() {
}
; CHECK-LABEL: @test25(
; CHECK: ret i32 0
; CHECK: llvm.objectsize
define i32 @test25() {
%1 = call i32 @llvm.objectsize.i32.p1i8(i8 addrspace(1)* null, i1 true,
i1 false)
@ -287,7 +287,7 @@ define i32 @test25() {
}
; CHECK-LABEL: @test26(
; CHECK: ret i32 0
; CHECK: llvm.objectsize
define i32 @test26() {
%1 = call i32 @llvm.objectsize.i32.p1i8(i8 addrspace(1)* null, i1 false,
i1 true)
@ -295,7 +295,7 @@ define i32 @test26() {
}
; CHECK-LABEL: @test27(
; CHECK: ret i32 0
; CHECK: llvm.objectsize
define i32 @test27() {
%1 = call i32 @llvm.objectsize.i32.p1i8(i8 addrspace(1)* null, i1 true,
i1 true)