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[flang][OpenMP][debug] Adjust debu info for declare target function.
The debug info for the function arguments and locals for the declare target functions needs following changes for AMDGPU target. 1. Add DIOp based expressions 2. If a debug reocrd points to function Argument as location then change it to use an alloca instead.
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‎flang/test/Integration/amdgpu/debug-declare-target-function-var.f90

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! RUN: %flang_fc1 -triple amdgcn-amd-amdhsa -emit-llvm -fopenmp -fopenmp-is-target-device -debug-info-kind=standalone %s -o - | FileCheck %s
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function add(a, b) result(ret)
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real ret
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real a
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real b
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!$omp declare target
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if (a > b) then
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ret = a;
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else
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ret = b;
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end if
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end
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!CHECK: define float @add_({{.*}}){{.*}}!dbg ![[SP:[0-9]+]] {
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!CHECK: #dbg_declare({{.*}}, ![[A:[0-9]+]], !DIExpression(DIOpArg(0, ptr addrspace(5)), DIOpDeref(ptr), DIOpDeref(ptr)), !{{.*}})
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!CHECK: #dbg_declare({{.*}}, ![[B:[0-9]+]], !DIExpression(DIOpArg(0, ptr addrspace(5)), DIOpDeref(ptr), DIOpDeref(ptr)), !{{.*}})
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!CHECK: #dbg_declare({{.*}}, ![[RET:[0-9]+]], !DIExpression(DIOpArg(0, ptr addrspace(5)), DIOpDeref(ptr)), !{{.*}})
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!CHECK: }
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!CHECK: ![[SP]] = {{.*}}!DISubprogram(name: "add"{{.*}})
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!CHECK: ![[A]] = !DILocalVariable(name: "a", arg: 1, scope: ![[SP]]{{.*}})
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!CHECK: ![[B]] = !DILocalVariable(name: "b", arg: 2, scope: ![[SP]]{{.*}})
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!CHECK: ![[RET]] = !DILocalVariable(name: "ret", scope: ![[SP]]{{.*}})

‎mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp

Lines changed: 67 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -39,6 +39,8 @@
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#include "llvm/TargetParser/Triple.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/ModuleUtils.h"
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#include "llvm/IR/InstIterator.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include <any>
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#include <cstdint>
@@ -5462,6 +5464,67 @@ static void updateDebugInfoForDeclareTargetVariables(
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}
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}
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// This function handle any adjustments needed in declare target function to
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// generate valid debug info for AMDGPU. It does 2 main things:
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// 1. Add DIOp based expressions
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// 2. If a debug reocrd points to function Argument as location then change it
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// to use an alloca instead.
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static void updateDebugInfoForDeclareTargetFunctions(
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llvm::Function *Fn, LLVM::ModuleTranslation &moduleTranslation) {
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llvm::OpenMPIRBuilder *ompBuilder = moduleTranslation.getOpenMPBuilder();
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llvm::Module &M = ompBuilder->M;
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if (!((llvm::Triple(M.getTargetTriple())).isAMDGPU()))
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return;
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llvm::IRBuilderBase &builder = ompBuilder->Builder;
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llvm::OpenMPIRBuilder::InsertPointTy curInsert = builder.saveIP();
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unsigned int allocaAS = M.getDataLayout().getAllocaAddrSpace();
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unsigned int defaultAS = M.getDataLayout().getProgramAddressSpace();
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// In most cases, function argument are passed by reference in Fortran. In
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// such cases, flang does not generate an alloca for such arguments. The
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// debug record also point to the Argument* as the location. The AMDGPU
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// backend drops the debug record in such cases. To side step this issue,
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// we generate an alloca and store the Argument pointer in it. Then we can
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// use that alloca as variable location and it works fine. Note that the
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// expression used in the debug record has doubel indirection now. One for
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// reading Argument* from the alloca and then reading the variable value from
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// the Argument*.
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auto genAlloca = [&](llvm::Value *Arg) {
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builder.SetInsertPoint(Fn->getEntryBlock().getFirstInsertionPt());
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llvm::Value *V = builder.CreateAlloca(Arg->getType(), allocaAS, nullptr);
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if (allocaAS != defaultAS && Arg->getType()->isPointerTy())
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V = ompBuilder->Builder.CreateAddrSpaceCast(V,
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builder.getPtrTy(defaultAS));
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builder.CreateStore(Arg, V);
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builder.restoreIP(curInsert);
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return V;
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};
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auto UpdateDebugRecord = [&](auto *DR) {
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for (auto Loc : DR->location_ops()) {
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llvm::DIExprBuilder ExprBuilder(Fn->getContext());
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ExprBuilder.append<llvm::DIOp::Arg>(
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0u, ompBuilder->Builder.getPtrTy(allocaAS));
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if (auto *Arg = dyn_cast<llvm::Argument>(Loc)) {
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ExprBuilder.append<llvm::DIOp::Deref>(
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ompBuilder->Builder.getPtrTy(defaultAS));
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llvm::Value *newLoc = genAlloca(Arg);
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DR->replaceVariableLocationOp(Arg, newLoc);
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}
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ExprBuilder.append<llvm::DIOp::Deref>(Loc->getType());
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DR->setExpression(ExprBuilder.intoExpression());
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}
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};
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for (llvm::Instruction &I : instructions(Fn)) {
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if (auto *DDI = dyn_cast<llvm::DbgVariableIntrinsic>(&I))
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UpdateDebugRecord(DDI);
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for (llvm::DbgVariableRecord &DVR : filterDbgVars(I.getDbgRecordRange()))
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UpdateDebugRecord(&DVR);
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}
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}
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static LogicalResult
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convertDeclareTargetAttr(Operation *op, mlir::omp::DeclareTargetAttr attribute,
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LLVM::ModuleTranslation &moduleTranslation) {
@@ -5481,12 +5544,13 @@ convertDeclareTargetAttr(Operation *op, mlir::omp::DeclareTargetAttr attribute,
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omp::DeclareTargetDeviceType declareType =
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attribute.getDeviceType().getValue();
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llvm::Function *llvmFunc =
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moduleTranslation.lookupFunction(funcOp.getName());
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if (declareType == omp::DeclareTargetDeviceType::host) {
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llvm::Function *llvmFunc =
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moduleTranslation.lookupFunction(funcOp.getName());
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llvmFunc->dropAllReferences();
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llvmFunc->eraseFromParent();
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}
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} else
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updateDebugInfoForDeclareTargetFunctions(llvmFunc, moduleTranslation);
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}
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return success();
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}

‎mlir/test/Target/LLVMIR/omptarget-decl-target-fn-debug-amdgpu.mlir

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// RUN: mlir-translate -mlir-to-llvmir %s | FileCheck %s
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#file = #llvm.di_file<"target.f90" in "">
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#cu = #llvm.di_compile_unit<id = distinct[0]<>,
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sourceLanguage = DW_LANG_Fortran95, file = #file, isOptimized = false,
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emissionKind = LineTablesOnly>
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#sp_ty = #llvm.di_subroutine_type<callingConvention = DW_CC_normal>
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#sp = #llvm.di_subprogram<id = distinct[1]<>, compileUnit = #cu, scope = #file,
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name = "add", file = #file, subprogramFlags = "Definition", type = #sp_ty>
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#ty = #llvm.di_basic_type<tag = DW_TAG_base_type, name = "real", sizeInBits = 32, encoding = DW_ATE_float>
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#var_a = #llvm.di_local_variable<scope = #sp, name = "a", file = #file, line = 22, arg = 1, type = #ty>
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module attributes {llvm.target_triple = "amdgcn-amd-amdhsa", omp.is_target_device = true, dlti.dl_spec = #dlti.dl_spec<"dlti.alloca_memory_space" = 5 : ui64>} {
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llvm.func @add(%arg0: !llvm.ptr) attributes {omp.declare_target = #omp.declaretarget<device_type = (any), capture_clause = (to)>} {
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llvm.intr.dbg.declare #var_a = %arg0 : !llvm.ptr loc(#loc2)
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llvm.return
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} loc(#loc3)
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}
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#loc1 = loc("target.f90":1:1)
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#loc2 = loc("target.f90":46:3)
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#loc3 = loc(fused<#sp>[#loc1])
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// CHECK: define{{.*}}@add(ptr %[[ARG:[0-9]+]]){{.*}}!dbg ![[SP:[0-9]+]] {
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// CHECK: %[[AL:[0-9]+]] = alloca{{.*}}
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// CHECK: %[[CAST:[0-9]+]] = addrspacecast ptr addrspace(5) %[[AL]]
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// CHECK: store ptr %[[ARG]], ptr %[[CAST]]{{.*}}
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// CHECK: #dbg_declare(ptr %[[CAST]], ![[A:[0-9]+]], !DIExpression(DIOpArg(0, ptr addrspace(5)), DIOpDeref(ptr), DIOpDeref(ptr)), !{{.*}})
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// CHECK: }
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// CHECK: ![[SP]] = {{.*}}!DISubprogram(name: "add"{{.*}})
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// CHECK: ![[A]] = !DILocalVariable(name: "a", arg: 1, scope: ![[SP]]{{.*}})
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