[llvm] 1d02de2 - [SPIRV] Implement translation for llvm.modf.* intrinsics (#147556)
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llvm-commits at lists.llvm.org
Mon Jul 21 05:51:38 PDT 2025
Author: Marcos Maronas
Date: 2025-07-21T14:51:34+02:00
New Revision: 1d02de28dd62c7fb007ae282a9c7f9412ff7e41d
URL: https://github.com/llvm/llvm-project/commit/1d02de28dd62c7fb007ae282a9c7f9412ff7e41d
DIFF: https://github.com/llvm/llvm-project/commit/1d02de28dd62c7fb007ae282a9c7f9412ff7e41d.diff
LOG: [SPIRV] Implement translation for llvm.modf.* intrinsics (#147556)
Based on
https://github.com/KhronosGroup/SPIRV-LLVM-Translator/pull/3100, I'm
adding translation for `llvm.modf.*` intrinsics.
Added:
Modified:
llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
llvm/lib/Target/SPIRV/SPIRVUtils.cpp
llvm/lib/Target/SPIRV/SPIRVUtils.h
llvm/test/CodeGen/SPIRV/llvm-intrinsics/fp-intrinsics.ll
Removed:
################################################################################
diff --git a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
index 6608b3f2cbefd..d4fa62a289202 100644
--- a/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp
@@ -296,6 +296,8 @@ class SPIRVInstructionSelector : public InstructionSelector {
bool selectImageWriteIntrinsic(MachineInstr &I) const;
bool selectResourceGetPointer(Register &ResVReg, const SPIRVType *ResType,
MachineInstr &I) const;
+ bool selectModf(Register ResVReg, const SPIRVType *ResType,
+ MachineInstr &I) const;
// Utilities
std::pair<Register, bool>
@@ -3235,6 +3237,9 @@ bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
case Intrinsic::spv_discard: {
return selectDiscard(ResVReg, ResType, I);
}
+ case Intrinsic::modf: {
+ return selectModf(ResVReg, ResType, I);
+ }
default: {
std::string DiagMsg;
raw_string_ostream OS(DiagMsg);
@@ -4018,6 +4023,83 @@ bool SPIRVInstructionSelector::selectLog10(Register ResVReg,
.constrainAllUses(TII, TRI, RBI);
}
+bool SPIRVInstructionSelector::selectModf(Register ResVReg,
+ const SPIRVType *ResType,
+ MachineInstr &I) const {
+ // llvm.modf has a single arg --the number to be decomposed-- and returns a
+ // struct { restype, restype }, while OpenCLLIB::modf has two args --the
+ // number to be decomposed and a pointer--, returns the fractional part and
+ // the integral part is stored in the pointer argument. Therefore, we can't
+ // use directly the OpenCLLIB::modf intrinsic. However, we can do some
+ // scaffolding to make it work. The idea is to create an alloca instruction
+ // to get a ptr, pass this ptr to OpenCL::modf, and then load the value
+ // from this ptr to place it in the struct. llvm.modf returns the fractional
+ // part as the first element of the result, and the integral part as the
+ // second element of the result.
+
+ // At this point, the return type is not a struct anymore, but rather two
+ // independent elements of SPIRVResType. We can get each independent element
+ // from I.getDefs() or I.getOperands().
+ if (STI.canUseExtInstSet(SPIRV::InstructionSet::OpenCL_std)) {
+ MachineIRBuilder MIRBuilder(I);
+ // Get pointer type for alloca variable.
+ const SPIRVType *PtrType = GR.getOrCreateSPIRVPointerType(
+ ResType, MIRBuilder, SPIRV::StorageClass::Function);
+ // Create new register for the pointer type of alloca variable.
+ Register PtrTyReg =
+ MIRBuilder.getMRI()->createVirtualRegister(&SPIRV::iIDRegClass);
+ MIRBuilder.getMRI()->setType(
+ PtrTyReg,
+ LLT::pointer(storageClassToAddressSpace(SPIRV::StorageClass::Function),
+ GR.getPointerSize()));
+ // Assign SPIR-V type of the pointer type of the alloca variable to the
+ // new register.
+ GR.assignSPIRVTypeToVReg(PtrType, PtrTyReg, MIRBuilder.getMF());
+ MachineBasicBlock &EntryBB = I.getMF()->front();
+ MachineBasicBlock::iterator VarPos =
+ getFirstValidInstructionInsertPoint(EntryBB);
+ auto AllocaMIB =
+ BuildMI(EntryBB, VarPos, I.getDebugLoc(), TII.get(SPIRV::OpVariable))
+ .addDef(PtrTyReg)
+ .addUse(GR.getSPIRVTypeID(PtrType))
+ .addImm(static_cast<uint32_t>(SPIRV::StorageClass::Function));
+ Register Variable = AllocaMIB->getOperand(0).getReg();
+ // Modf must have 4 operands, the first two are the 2 parts of the result,
+ // the third is the operand, and the last one is the floating point value.
+ assert(I.getNumOperands() == 4 &&
+ "Expected 4 operands for modf instruction");
+ MachineBasicBlock &BB = *I.getParent();
+ // Create the OpenCLLIB::modf instruction.
+ auto MIB =
+ BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpExtInst))
+ .addDef(ResVReg)
+ .addUse(GR.getSPIRVTypeID(ResType))
+ .addImm(static_cast<uint32_t>(SPIRV::InstructionSet::OpenCL_std))
+ .addImm(CL::modf)
+ .setMIFlags(I.getFlags())
+ .add(I.getOperand(3)) // Floating point value.
+ .addUse(Variable); // Pointer to integral part.
+ // Assign the integral part stored in the ptr to the second element of the
+ // result.
+ Register IntegralPartReg = I.getOperand(1).getReg();
+ if (IntegralPartReg.isValid()) {
+ // Load the value from the pointer to integral part.
+ auto LoadMIB = BuildMI(BB, I, I.getDebugLoc(), TII.get(SPIRV::OpLoad))
+ .addDef(IntegralPartReg)
+ .addUse(GR.getSPIRVTypeID(ResType))
+ .addUse(Variable);
+ return LoadMIB.constrainAllUses(TII, TRI, RBI);
+ }
+
+ return MIB.constrainAllUses(TII, TRI, RBI);
+ } else if (STI.canUseExtInstSet(SPIRV::InstructionSet::GLSL_std_450)) {
+ assert(false && "GLSL::Modf is deprecated.");
+ // FIXME: GL::Modf is deprecated, use Modfstruct instead.
+ return false;
+ }
+ return false;
+}
+
// Generate the instructions to load 3-element vector builtin input
// IDs/Indices.
// Like: GlobalInvocationId, LocalInvocationId, etc....
diff --git a/llvm/lib/Target/SPIRV/SPIRVUtils.cpp b/llvm/lib/Target/SPIRV/SPIRVUtils.cpp
index 768efb96a53e9..416d811ba4e65 100644
--- a/llvm/lib/Target/SPIRV/SPIRVUtils.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVUtils.cpp
@@ -995,4 +995,27 @@ unsigned getArrayComponentCount(const MachineRegisterInfo *MRI,
return foldImm(ResType->getOperand(2), MRI);
}
+MachineBasicBlock::iterator
+getFirstValidInstructionInsertPoint(MachineBasicBlock &BB) {
+ // Find the position to insert the OpVariable instruction.
+ // We will insert it after the last OpFunctionParameter, if any, or
+ // after OpFunction otherwise.
+ MachineBasicBlock::iterator VarPos = BB.begin();
+ while (VarPos != BB.end() && VarPos->getOpcode() != SPIRV::OpFunction) {
+ ++VarPos;
+ }
+ // Advance VarPos to the next instruction after OpFunction, it will either
+ // be an OpFunctionParameter, so that we can start the next loop, or the
+ // position to insert the OpVariable instruction.
+ ++VarPos;
+ while (VarPos != BB.end() &&
+ VarPos->getOpcode() == SPIRV::OpFunctionParameter) {
+ ++VarPos;
+ }
+ // VarPos is now pointing at after the last OpFunctionParameter, if any,
+ // or after OpFunction, if no parameters.
+ return VarPos != BB.end() && VarPos->getOpcode() == SPIRV::OpLabel ? ++VarPos
+ : VarPos;
+}
+
} // namespace llvm
diff --git a/llvm/lib/Target/SPIRV/SPIRVUtils.h b/llvm/lib/Target/SPIRV/SPIRVUtils.h
index d732188f9289f..45c520a922d10 100644
--- a/llvm/lib/Target/SPIRV/SPIRVUtils.h
+++ b/llvm/lib/Target/SPIRV/SPIRVUtils.h
@@ -506,6 +506,8 @@ MachineInstr *getImm(const MachineOperand &MO, const MachineRegisterInfo *MRI);
int64_t foldImm(const MachineOperand &MO, const MachineRegisterInfo *MRI);
unsigned getArrayComponentCount(const MachineRegisterInfo *MRI,
const MachineInstr *ResType);
+MachineBasicBlock::iterator
+getFirstValidInstructionInsertPoint(MachineBasicBlock &BB);
} // namespace llvm
#endif // LLVM_LIB_TARGET_SPIRV_SPIRVUTILS_H
diff --git a/llvm/test/CodeGen/SPIRV/llvm-intrinsics/fp-intrinsics.ll b/llvm/test/CodeGen/SPIRV/llvm-intrinsics/fp-intrinsics.ll
index 3d46b527bf14f..70030ca1a0316 100644
--- a/llvm/test/CodeGen/SPIRV/llvm-intrinsics/fp-intrinsics.ll
+++ b/llvm/test/CodeGen/SPIRV/llvm-intrinsics/fp-intrinsics.ll
@@ -1,4 +1,5 @@
; 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: %[[#extinst_id:]] = OpExtInstImport "OpenCL.std"
@@ -337,3 +338,68 @@ entry:
}
declare float @llvm.fma.f32(float, float, float)
+
+; CHECK: OpFunction
+; CHECK: %[[#d:]] = OpFunctionParameter %[[#]]
+; CHECK: %[[#fracPtr:]] = OpFunctionParameter %[[#]]
+; CHECK: %[[#integralPtr:]] = OpFunctionParameter %[[#]]
+; CHECK: %[[#varPtr:]] = OpVariable %[[#]] Function
+; CHECK: %[[#frac:]] = OpExtInst %[[#var2]] %[[#extinst_id]] modf %[[#d]] %[[#varPtr]]
+; CHECK: %[[#integral:]] = OpLoad %[[#var2]] %[[#varPtr]]
+; CHECK: OpStore %[[#fracPtr]] %[[#frac]]
+; CHECK: OpStore %[[#integralPtr]] %[[#integral]]
+; CHECK: OpFunctionEnd
+define void @TestModf(double %d, ptr addrspace(1) %frac, ptr addrspace(1) %integral) {
+entry:
+ %4 = tail call { double, double } @llvm.modf.f64(double %d)
+ %5 = extractvalue { double, double } %4, 0
+ %6 = extractvalue { double, double } %4, 1
+ store double %5, ptr addrspace(1) %frac, align 8
+ store double %6, ptr addrspace(1) %integral, align 8
+ ret void
+}
+
+; CHECK: OpFunction
+; CHECK: %[[#d:]] = OpFunctionParameter %[[#]]
+; CHECK: %[[#fracPtr:]] = OpFunctionParameter %[[#]]
+; CHECK: %[[#integralPtr:]] = OpFunctionParameter %[[#]]
+; CHECK: %[[#entryBlock:]] = OpLabel
+; CHECK: %[[#varPtr:]] = OpVariable %[[#]] Function
+; CHECK: OpBranchConditional %[[#]] %[[#lor_lhs_falseBlock:]] %[[#if_thenBlock:]]
+; CHECK: %[[#lor_lhs_falseBlock]] = OpLabel
+; CHECK: OpBranchConditional %[[#]] %[[#if_endBlock:]] %[[#if_thenBlock]]
+; CHECK: %[[#if_thenBlock]] = OpLabel
+; CHECK: OpBranch %[[#returnBlock:]]
+; CHECK: %[[#if_endBlock]] = OpLabel
+; CHECK: %[[#frac:]] = OpExtInst %[[#var2]] %[[#extinst_id]] modf %[[#d]] %[[#varPtr]]
+; CHECK: %[[#integral:]] = OpLoad %[[#var2]] %[[#varPtr]]
+; CHECK: OpStore %[[#fracPtr]] %[[#frac]]
+; CHECK: OpStore %[[#integralPtr]] %[[#integral]]
+; CHECK: OpFunctionEnd
+define dso_local void @TestModf2(double noundef %d, ptr noundef %frac, ptr noundef %integral) {
+entry:
+ %0 = load ptr, ptr %frac, align 8
+ %tobool = icmp ne ptr %0, null
+ br i1 %tobool, label %lor.lhs.false, label %if.then
+
+lor.lhs.false:
+ %1 = load ptr, ptr %integral, align 8
+ %tobool1 = icmp ne ptr %1, null
+ br i1 %tobool1, label %if.end, label %if.then
+
+if.then:
+ br label %return
+
+if.end:
+ %6 = tail call { double, double } @llvm.modf.f64(double %d)
+ %7 = extractvalue { double, double } %6, 0
+ %8 = extractvalue { double, double } %6, 1
+ store double %7, ptr %frac, align 4
+ store double %8, ptr %integral, align 4
+ br label %return
+
+return:
+ ret void
+}
+
+declare { double, double } @llvm.modf.f64(double)
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