[llvm] [SPIRV] Handle `inttoptr` constant expressions in global initialisers (PR #166494)
Alex Voicu via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 4 19:06:57 PST 2025
https://github.com/AlexVlx created https://github.com/llvm/llvm-project/pull/166494
`inttoptr` usage in global initialisers is valid, and rather common when it comes to the machinery around vtables (construction vtables are particularly fond). This was not handled by the BE, even though SPIR-V allows forming `SpecConstantOp`s with the `OpConvertUToPtr` opcode, which is what these would map to. We augment instruction selection to address this.
>From b80da0e2ecb20a50d0b388278cd579f58609c1fa Mon Sep 17 00:00:00 2001
From: Alex Voicu <alexandru.voicu at amd.com>
Date: Wed, 5 Nov 2025 02:42:16 +0000
Subject: [PATCH] Handle `inttoptr` constant expressions in global
initialisers.
---
.../Target/SPIRV/SPIRVInstructionSelector.cpp | 16 ++++--
llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp | 11 +++++
.../transcoding/ConvertPtrInGlobalInit.ll | 49 +++++++++++++++++++
3 files changed, 73 insertions(+), 3 deletions(-)
create mode 100644 llvm/test/CodeGen/SPIRV/transcoding/ConvertPtrInGlobalInit.ll
diff --git a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
index 3f0424f436c72..b00b6bd164421 100644
--- a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
@@ -1210,8 +1210,17 @@ bool SPIRVInstructionSelector::selectUnOp(Register ResVReg,
for (MachineRegisterInfo::def_instr_iterator DefIt =
MRI->def_instr_begin(SrcReg);
DefIt != MRI->def_instr_end(); DefIt = std::next(DefIt)) {
- if ((*DefIt).getOpcode() == TargetOpcode::G_GLOBAL_VALUE ||
- (*DefIt).getOpcode() == SPIRV::OpVariable) {
+ unsigned DefOpCode = (*DefIt).getOpcode();
+ if (DefOpCode == SPIRV::ASSIGN_TYPE) {
+ // We need special handling to look through the type assignment and see
+ // if this is a constant or a global
+ if (auto *VRD = getVRegDef(*MRI, (*DefIt).getOperand(1).getReg()))
+ DefOpCode = VRD->getOpcode();
+ }
+ if (DefOpCode == TargetOpcode::G_GLOBAL_VALUE ||
+ DefOpCode == TargetOpcode::G_CONSTANT ||
+ DefOpCode == SPIRV::OpVariable ||
+ DefOpCode == SPIRV::OpConstantI) {
IsGV = true;
break;
}
@@ -3099,9 +3108,10 @@ bool SPIRVInstructionSelector::wrapIntoSpecConstantOp(
SmallPtrSet<SPIRVType *, 4> Visited;
if (!OpDefine || !OpType || isConstReg(MRI, OpDefine, Visited) ||
OpDefine->getOpcode() == TargetOpcode::G_ADDRSPACE_CAST ||
+ OpDefine->getOpcode() == TargetOpcode::G_INTTOPTR ||
GR.isAggregateType(OpType)) {
// The case of G_ADDRSPACE_CAST inside spv_const_composite() is processed
- // by selectAddrSpaceCast()
+ // by selectAddrSpaceCast(), and G_INTTOPTR is processed by selectUnOp()
CompositeArgs.push_back(OpReg);
continue;
}
diff --git a/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp b/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp
index d538009f0ecbe..128403a646787 100644
--- a/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp
@@ -348,6 +348,16 @@ static SPIRVType *propagateSPIRVType(MachineInstr *MI, SPIRVGlobalRegistry *GR,
SpvType = GR->getOrCreateSPIRVIntegerType(
MRI.getType(Reg).getScalarSizeInBits(), MIB);
break;
+ case TargetOpcode::G_INTTOPTR:
+ // With opaque pointers it doesn't appear as if we can convert to
+ // anything but a pointer to i8
+ SpvType = GR->getOrCreateSPIRVPointerType(
+ GR->getOrCreateSPIRVIntegerType(8, MIB),
+ MIB,
+ addressSpaceToStorageClass(
+ MRI.getType(Reg).getAddressSpace(),
+ MIB.getMF().getSubtarget<SPIRVSubtarget>()));
+ break;
case TargetOpcode::G_TRUNC:
case TargetOpcode::G_ADDRSPACE_CAST:
case TargetOpcode::G_PTR_ADD:
@@ -684,6 +694,7 @@ generateAssignInstrs(MachineFunction &MF, SPIRVGlobalRegistry *GR,
case TargetOpcode::G_SEXT:
case TargetOpcode::G_ZEXT:
case TargetOpcode::G_PTRTOINT:
+ case TargetOpcode::G_INTTOPTR:
case TargetOpcode::COPY:
case TargetOpcode::G_ADDRSPACE_CAST:
propagateSPIRVType(&MI, GR, MRI, MIB);
diff --git a/llvm/test/CodeGen/SPIRV/transcoding/ConvertPtrInGlobalInit.ll b/llvm/test/CodeGen/SPIRV/transcoding/ConvertPtrInGlobalInit.ll
new file mode 100644
index 0000000000000..614c126e02656
--- /dev/null
+++ b/llvm/test/CodeGen/SPIRV/transcoding/ConvertPtrInGlobalInit.ll
@@ -0,0 +1,49 @@
+; RUN: llc -O0 -mtriple=spirv64-unknown-unknown %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv64-unknown-unknown %s -o - -filetype=obj | spirv-val %}
+
+; CHECK: %[[Int8Ty:[0-9]+]] = OpTypeInt 8 0
+; CHECK: %[[Int8PtrTy:[0-9]+]] = OpTypePointer Generic %[[Int8Ty]]
+; CHECK-DAG: %[[GlobInt8PtrTy:[0-9]+]] = OpTypePointer CrossWorkgroup %[[Int8Ty]]
+; CHECK: %[[GlobInt8PtrPtrTy:[0-9]+]] = OpTypePointer CrossWorkgroup %[[GlobInt8PtrTy]]
+; CHECK: %[[Int8PtrGlobPtrPtrTy:[0-9]+]] = OpTypePointer Generic %[[GlobInt8PtrPtrTy]]
+; CHECK: %[[Int32Ty:[0-9]+]] = OpTypeInt 32 0
+; CHECK: %[[Const5:[0-9]+]] = OpConstant %[[Int32Ty]] 5
+; CHECK: %[[ArrTy:[0-9]+]] = OpTypeArray %[[GlobInt8PtrTy]] %[[Const5]]
+; CHECK: %[[VtblTy:[0-9]+]] = OpTypeStruct %[[ArrTy]] %[[ArrTy]] %[[ArrTy]] %[[ArrTy]] %[[ArrTy]]
+; CHECK: %[[Int64Ty:[0-9]+]] = OpTypeInt 64 0
+; CHECK: %[[GlobVtblPtrTy:[0-9]+]] = OpTypePointer CrossWorkgroup %[[VtblTy]]
+; CHECK: %[[ConstMinus184:[0-9]+]] = OpConstant %[[Int64Ty]] 18446744073709551432
+; CHECK: %[[ConstMinus16:[0-9]+]] = OpConstant %[[Int64Ty]] 18446744073709551600
+; CHECK: %[[Const168:[0-9]+]] = OpConstant %[[Int64Ty]] 168
+; CHECK: %[[Const184:[0-9]+]] = OpConstant %[[Int64Ty]] 184
+; CHECK: %[[Nullptr:[0-9]+]] = OpConstantNull %[[GlobInt8PtrTy]]
+; CHECK: %[[Const184toPtr:[0-9]+]] = OpSpecConstantOp %[[GlobInt8PtrTy]] ConvertUToPtr %[[Const184]]
+; CHECK: %[[Const168toPtr:[0-9]+]] = OpSpecConstantOp %[[GlobInt8PtrTy]] ConvertUToPtr %[[Const168]]
+; CHECK: %[[ConstMinus16toPtr:[0-9]+]] = OpSpecConstantOp %[[GlobInt8PtrTy]] ConvertUToPtr %[[ConstMinus16]]
+; CHECK: %[[ConstMinus184toPtr:[0-9]+]] = OpSpecConstantOp %[[GlobInt8PtrTy]] ConvertUToPtr %[[ConstMinus184]]
+; CHECK: %[[Vtbl012:[0-9]+]] = OpConstantComposite %[[ArrTy]] %[[Const184toPtr]] %[[Nullptr]] %[[Nullptr]] %[[Nullptr]] %[[Nullptr]]
+; CHECK: %[[Vtbl3:[0-9]+]] = OpConstantComposite %[[ArrTy]] %[[Const168toPtr]] %[[ConstMinus16toPtr]] %[[Nullptr]] %[[Nullptr]] %[[Nullptr]]
+; CHECK: %[[Vtbl4:[0-9]+]] = OpConstantComposite %[[ArrTy]] %[[ConstMinus184toPtr]] %[[ConstMinus184toPtr]] %[[Nullptr]] %[[Nullptr]] %[[Nullptr]]
+; CHECK: %[[Vtbl:[0-9]+]] = OpConstantComposite %[[VtblTy]] %[[Vtbl012]] %[[Vtbl012]] %[[Vtbl012]] %[[Vtbl3]] %[[Vtbl4]]
+; CHECK: %[[#]] = OpVariable %[[GlobVtblPtrTy]] CrossWorkgroup %[[Vtbl]]
+
+ at vtable = linkonce_odr unnamed_addr addrspace(1) constant { [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)] }
+ { [5 x ptr addrspace(1)] [ptr addrspace(1) inttoptr (i64 184 to ptr addrspace(1)), ptr addrspace(1) null, ptr addrspace(1) null, ptr addrspace(1) null, ptr addrspace(1) null],
+ [5 x ptr addrspace(1)] [ptr addrspace(1) inttoptr (i64 184 to ptr addrspace(1)), ptr addrspace(1) null, ptr addrspace(1) null, ptr addrspace(1) null, ptr addrspace(1) null],
+ [5 x ptr addrspace(1)] [ptr addrspace(1) inttoptr (i64 184 to ptr addrspace(1)), ptr addrspace(1) null, ptr addrspace(1) null, ptr addrspace(1) null, ptr addrspace(1) null],
+ [5 x ptr addrspace(1)] [ptr addrspace(1) inttoptr (i64 168 to ptr addrspace(1)), ptr addrspace(1) inttoptr (i64 -16 to ptr addrspace(1)), ptr addrspace(1) null, ptr addrspace(1) null, ptr addrspace(1) null],
+ [5 x ptr addrspace(1)] [ptr addrspace(1) inttoptr (i64 -184 to ptr addrspace(1)), ptr addrspace(1) inttoptr (i64 -184 to ptr addrspace(1)), ptr addrspace(1) null, ptr addrspace(1) null, ptr addrspace(1) null] }
+
+define linkonce_odr spir_func void @foo(ptr addrspace(4) %this) {
+entry:
+ %0 = getelementptr inbounds i8, ptr addrspace(4) %this, i64 184
+ store ptr addrspace(1) getelementptr inbounds inrange(-24, 16) ({ [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)] }, ptr addrspace(1) @vtable, i32 0, i32 0, i32 3), ptr addrspace(4) %this
+ store ptr addrspace(1) getelementptr inbounds inrange(-24, 16) ({ [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)] }, ptr addrspace(1) @vtable, i32 0, i32 1, i32 3), ptr addrspace(4) %this
+ store ptr addrspace(1) getelementptr inbounds inrange(-24, 16) ({ [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)] }, ptr addrspace(1) @vtable, i32 0, i32 2, i32 3), ptr addrspace(4) %this
+ %add.ptr = getelementptr inbounds i8, ptr addrspace(4) %this, i64 184
+ store ptr addrspace(1) getelementptr inbounds inrange(-24, 16) ({ [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)] }, ptr addrspace(1) @vtable, i32 0, i32 4, i32 3), ptr addrspace(4) %add.ptr
+ %add.ptr2 = getelementptr inbounds i8, ptr addrspace(4) %this, i64 16
+ store ptr addrspace(1) getelementptr inbounds inrange(-24, 16) ({ [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)], [5 x ptr addrspace(1)] }, ptr addrspace(1) @vtable, i32 0, i32 3, i32 3), ptr addrspace(4) %add.ptr2
+
+ ret void
+}
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