diff --git a/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp b/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp index 3c2af34dd5523..cc34cf877dea9 100644 --- a/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp +++ b/llvm/lib/Target/SPIRV/SPIRVPreLegalizer.cpp @@ -165,6 +165,57 @@ static MachineInstr *findAssignTypeInstr(Register Reg, return nullptr; } +static void buildOpBitcast(SPIRVGlobalRegistry *GR, MachineIRBuilder &MIB, + Register ResVReg, Register OpReg) { + SPIRVType *ResType = GR->getSPIRVTypeForVReg(ResVReg); + SPIRVType *OpType = GR->getSPIRVTypeForVReg(OpReg); + assert(ResType && OpType && "Operand types are expected"); + if (!GR->isBitcastCompatible(ResType, OpType)) + report_fatal_error("incompatible result and operand types in a bitcast"); + MachineRegisterInfo *MRI = MIB.getMRI(); + if (!MRI->getRegClassOrNull(ResVReg)) + MRI->setRegClass(ResVReg, GR->getRegClass(ResType)); + MIB.buildInstr(SPIRV::OpBitcast) + .addDef(ResVReg) + .addUse(GR->getSPIRVTypeID(ResType)) + .addUse(OpReg); +} + +// We do instruction selections early instead of calling MIB.buildBitcast() +// generating the general op code G_BITCAST. When MachineVerifier validates +// G_BITCAST we see a check of a kind: if Source Type is equal to Destination +// Type then report error "bitcast must change the type". This doesn't take into +// account the notion of a typed pointer that is important for SPIR-V where a +// user may and should use bitcast between pointers with different pointee types +// (https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#OpBitcast). +// It's important for correct lowering in SPIR-V, because interpretation of the +// data type is not left to instructions that utilize the pointer, but encoded +// by the pointer declaration, and the SPIRV target can and must handle the +// declaration and use of pointers that specify the type of data they point to. +// It's not feasible to improve validation of G_BITCAST using just information +// provided by low level types of source and destination. Therefore we don't +// produce G_BITCAST as the general op code with semantics different from +// OpBitcast, but rather lower to OpBitcast immediately. As for now, the only +// difference would be that CombinerHelper couldn't transform known patterns +// around G_BUILD_VECTOR. See discussion +// in https://github.com/llvm/llvm-project/pull/110270 for even more context. +static void selectOpBitcasts(MachineFunction &MF, SPIRVGlobalRegistry *GR, + MachineIRBuilder MIB) { + SmallVector ToErase; + for (MachineBasicBlock &MBB : MF) { + for (MachineInstr &MI : MBB) { + if (MI.getOpcode() != TargetOpcode::G_BITCAST) + continue; + MIB.setInsertPt(*MI.getParent(), MI); + buildOpBitcast(GR, MIB, MI.getOperand(0).getReg(), + MI.getOperand(1).getReg()); + ToErase.push_back(&MI); + } + } + for (MachineInstr *MI : ToErase) + MI->eraseFromParent(); +} + static void insertBitcasts(MachineFunction &MF, SPIRVGlobalRegistry *GR, MachineIRBuilder MIB) { // Get access to information about available extensions @@ -202,15 +253,6 @@ static void insertBitcasts(MachineFunction &MF, SPIRVGlobalRegistry *GR, } else { GR->assignSPIRVTypeToVReg(AssignedPtrType, Def, MF); MIB.buildBitcast(Def, Source); - // MachineVerifier requires that bitcast must change the type. - // Change AddressSpace if needed to hint that Def and Source points to - // different types: this doesn't change actual code generation. - LLT DefType = MRI->getType(Def); - if (DefType == MRI->getType(Source)) - MRI->setType(Def, - LLT::pointer((DefType.getAddressSpace() + 1) % - SPIRVSubtarget::MaxLegalAddressSpace, - GR->getPointerSize())); } } } @@ -1007,6 +1049,7 @@ bool SPIRVPreLegalizer::runOnMachineFunction(MachineFunction &MF) { removeImplicitFallthroughs(MF, MIB); insertSpirvDecorations(MF, MIB); insertInlineAsm(MF, GR, ST, MIB); + selectOpBitcasts(MF, GR, MIB); return true; } diff --git a/llvm/test/CodeGen/SPIRV/pointers/phi-valid-operand-types-rev.ll b/llvm/test/CodeGen/SPIRV/pointers/phi-valid-operand-types-rev.ll index 6fa3f4e53cc59..8d14c3a359963 100644 --- a/llvm/test/CodeGen/SPIRV/pointers/phi-valid-operand-types-rev.ll +++ b/llvm/test/CodeGen/SPIRV/pointers/phi-valid-operand-types-rev.ll @@ -1,7 +1,4 @@ -; The goal of the test case is to ensure that OpPhi is consistent with respect to operand types. -; -verify-machineinstrs is not available due to mutually exclusive requirements for G_BITCAST and G_PHI. - -; RUN: llc -O0 -mtriple=spirv64-unknown-unknown %s -o - | FileCheck %s +; RUN: llc -verify-machineinstrs -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: %[[#Char:]] = OpTypeInt 8 0 diff --git a/llvm/test/CodeGen/SPIRV/pointers/phi-valid-operand-types.ll b/llvm/test/CodeGen/SPIRV/pointers/phi-valid-operand-types.ll index 4fbaae2556730..07824d4ed6cd8 100644 --- a/llvm/test/CodeGen/SPIRV/pointers/phi-valid-operand-types.ll +++ b/llvm/test/CodeGen/SPIRV/pointers/phi-valid-operand-types.ll @@ -1,7 +1,4 @@ -; The goal of the test case is to ensure that OpPhi is consistent with respect to operand types. -; -verify-machineinstrs is not available due to mutually exclusive requirements for G_BITCAST and G_PHI. - -; RUN: llc -O0 -mtriple=spirv64-unknown-unknown %s -o - | FileCheck %s +; RUN: llc -verify-machineinstrs -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: %[[#Char:]] = OpTypeInt 8 0