Skip to content

[AMDGPU][LowerBufferFatPointers] Handle addrspacecast null to p7 #140775

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
May 20, 2025
+100 −4
Merged

[AMDGPU][LowerBufferFatPointers] Handle addrspacecast null to p7 #140775

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
1639578
[AMDGPU][LowerBufferFatPointers] Handle addrspacecast null to p7
krzysz00 May 20, 2025
68dac67
Undef and poison
krzysz00 May 20, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
36 changes: 32 additions & 4 deletions llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1980,6 +1980,8 @@ PtrParts SplitPtrStructs::visitIntToPtrInst(IntToPtrInst &IP) {
}

PtrParts SplitPtrStructs::visitAddrSpaceCastInst(AddrSpaceCastInst &I) {
// TODO(krzysz00): handle casts from ptr addrspace(7) to global pointers
// by computing the effective address.
if (!isSplitFatPtr(I.getType()))
return {nullptr, nullptr};
IRB.SetInsertPoint(&I);
Expand All @@ -1990,11 +1992,37 @@ PtrParts SplitPtrStructs::visitAddrSpaceCastInst(AddrSpaceCastInst &I) {
SplitUsers.insert(&I);
return {Rsrc, Off};
}
if (I.getSrcAddressSpace() != AMDGPUAS::BUFFER_RESOURCE)
report_fatal_error("Only buffer resources (addrspace 8) can be cast to "
"buffer fat pointers (addrspace 7)");
Type *OffTy = cast<StructType>(I.getType())->getElementType(1);

auto *ResTy = cast<StructType>(I.getType());
Type *RsrcTy = ResTy->getElementType(0);
Type *OffTy = ResTy->getElementType(1);
Value *ZeroOff = Constant::getNullValue(OffTy);

// Special case for null pointers, undef, and poison, which can be created by
// address space propagation.
auto *InConst = dyn_cast<Constant>(In);
if (InConst && InConst->isNullValue()) {
Value *NullRsrc = Constant::getNullValue(RsrcTy);
SplitUsers.insert(&I);
return {NullRsrc, ZeroOff};
}
if (isa<PoisonValue>(In)) {
Value *PoisonRsrc = PoisonValue::get(RsrcTy);
Value *PoisonOff = PoisonValue::get(OffTy);
SplitUsers.insert(&I);
return {PoisonRsrc, PoisonOff};
}
if (isa<UndefValue>(In)) {
Value *UndefRsrc = UndefValue::get(RsrcTy);
Value *UndefOff = UndefValue::get(OffTy);
SplitUsers.insert(&I);
return {UndefRsrc, UndefOff};
}

if (I.getSrcAddressSpace() != AMDGPUAS::BUFFER_RESOURCE)
report_fatal_error(
"only buffer resources (addrspace 8) and null/poison pointers can be "
"cast to buffer fat pointers (addrspace 7)");
SplitUsers.insert(&I);
return {In, ZeroOff};
}
Expand Down
68 changes: 68 additions & 0 deletions llvm/test/CodeGen/AMDGPU/lower-buffer-fat-pointers-pointer-ops.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -332,6 +332,74 @@ define <2 x ptr addrspace(7)> @addrspacecast_vec(<2 x ptr addrspace(8)> %buf) {
ret <2 x ptr addrspace(7)> %ret
}

define ptr addrspace(7) @addrspacecast_null() {
; CHECK-LABEL: define { ptr addrspace(8), i32 } @addrspacecast_null
; CHECK-SAME: () #[[ATTR0]] {
; CHECK-NEXT: ret { ptr addrspace(8), i32 } zeroinitializer
;
%ret = addrspacecast ptr null to ptr addrspace(7)
ret ptr addrspace(7) %ret
}

define <2 x ptr addrspace(7)> @addrspacecast_null_vec() {
; CHECK-LABEL: define { <2 x ptr addrspace(8)>, <2 x i32> } @addrspacecast_null_vec
; CHECK-SAME: () #[[ATTR0]] {
; CHECK-NEXT: ret { <2 x ptr addrspace(8)>, <2 x i32> } zeroinitializer
;
%ret = addrspacecast <2 x ptr> zeroinitializer to <2 x ptr addrspace(7)>
ret <2 x ptr addrspace(7)> %ret
}

define i1 @test_null(ptr addrspace(7) %p) {
; CHECK-LABEL: define i1 @test_null
; CHECK-SAME: ({ ptr addrspace(8), i32 } [[P:%.*]]) #[[ATTR0]] {
; CHECK-NEXT: [[P_RSRC:%.*]] = extractvalue { ptr addrspace(8), i32 } [[P]], 0
; CHECK-NEXT: [[P_OFF:%.*]] = extractvalue { ptr addrspace(8), i32 } [[P]], 1
; CHECK-NEXT: [[IS_NULL_RSRC:%.*]] = icmp eq ptr addrspace(8) [[P_RSRC]], null
; CHECK-NEXT: [[IS_NULL_OFF:%.*]] = icmp eq i32 [[P_OFF]], 0
; CHECK-NEXT: [[IS_NULL:%.*]] = and i1 [[IS_NULL_RSRC]], [[IS_NULL_OFF]]
; CHECK-NEXT: ret i1 [[IS_NULL]]
;
%is.null = icmp eq ptr addrspace(7) %p, addrspacecast (ptr null to ptr addrspace(7))
ret i1 %is.null
}

define ptr addrspace(7) @addrspacecast_undef() {
; CHECK-LABEL: define { ptr addrspace(8), i32 } @addrspacecast_undef
; CHECK-SAME: () #[[ATTR0]] {
; CHECK-NEXT: ret { ptr addrspace(8), i32 } undef
;
%ret = addrspacecast ptr undef to ptr addrspace(7)
ret ptr addrspace(7) %ret
}

define <2 x ptr addrspace(7)> @addrspacecast_undef_vec() {
; CHECK-LABEL: define { <2 x ptr addrspace(8)>, <2 x i32> } @addrspacecast_undef_vec
; CHECK-SAME: () #[[ATTR0]] {
; CHECK-NEXT: ret { <2 x ptr addrspace(8)>, <2 x i32> } undef
;
%ret = addrspacecast <2 x ptr> undef to <2 x ptr addrspace(7)>
ret <2 x ptr addrspace(7)> %ret
}

define ptr addrspace(7) @addrspacecast_poison() {
; CHECK-LABEL: define { ptr addrspace(8), i32 } @addrspacecast_poison
; CHECK-SAME: () #[[ATTR0]] {
; CHECK-NEXT: ret { ptr addrspace(8), i32 } poison
;
%ret = addrspacecast ptr poison to ptr addrspace(7)
ret ptr addrspace(7) %ret
}

define <2 x ptr addrspace(7)> @addrspacecast_poison_vec() {
; CHECK-LABEL: define { <2 x ptr addrspace(8)>, <2 x i32> } @addrspacecast_poison_vec
; CHECK-SAME: () #[[ATTR0]] {
; CHECK-NEXT: ret { <2 x ptr addrspace(8)>, <2 x i32> } poison
;
%ret = addrspacecast <2 x ptr> poison to <2 x ptr addrspace(7)>
ret <2 x ptr addrspace(7)> %ret
}

declare ptr addrspace(7) @llvm.amdgcn.make.buffer.rsrc.p7.p1(ptr addrspace(1), i16, i32, i32)

define ptr addrspace(7) @make_buffer_rsrc(ptr addrspace(1) %buf, i16 %stride, i32 %numRecords, i32 %flags) {
Expand Down
Loading