Rename the lowering dir to lower (#3172)

This is continuing with #3070, starting dir renaming with lowering because it's at the tip. AFAICT git is catching all the file moves.
2026-10-03 22:02:51 +01:00 · 2023-08-31 15:59:49 +00:00
parent 907be6465f
commit ec307b18d8
72 changed files with 34 additions and 34 deletions
@@ -0,0 +1,113 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include "toolchain/lower/function_context.h"
+
+#include "toolchain/semantics/semantics_ir.h"
+
+namespace Carbon::Lower {
+
+FunctionContext::FunctionContext(FileContext& file_context,
+                                 llvm::Function* function)
+    : file_context_(&file_context),
+      function_(function),
+      builder_(file_context.llvm_context()) {}
+
+auto FunctionContext::GetBlock(SemIR::NodeBlockId block_id)
+    -> llvm::BasicBlock* {
+  llvm::BasicBlock*& entry = blocks_[block_id];
+  if (!entry) {
+    entry = llvm::BasicBlock::Create(llvm_context(), "", function_);
+  }
+  return entry;
+}
+
+auto FunctionContext::TryToReuseBlock(SemIR::NodeBlockId block_id,
+                                      llvm::BasicBlock* block) -> bool {
+  if (!blocks_.insert({block_id, block}).second) {
+    return false;
+  }
+  if (block == synthetic_block_) {
+    synthetic_block_ = nullptr;
+  }
+  return true;
+}
+
+auto FunctionContext::GetBlockArg(SemIR::NodeBlockId block_id,
+                                  SemIR::TypeId type_id) -> llvm::PHINode* {
+  llvm::BasicBlock* block = GetBlock(block_id);
+
+  // Find the existing phi, if any.
+  auto phis = block->phis();
+  if (!phis.empty()) {
+    CARBON_CHECK(std::next(phis.begin()) == phis.end())
+        << "Expected at most one phi, found "
+        << std::distance(phis.begin(), phis.end());
+    return &*phis.begin();
+  }
+
+  // The number of predecessor slots to reserve.
+  static constexpr unsigned NumReservedPredecessors = 2;
+  auto* phi = llvm::PHINode::Create(GetType(type_id), NumReservedPredecessors);
+  phi->insertInto(block, block->begin());
+  return phi;
+}
+
+auto FunctionContext::CreateSyntheticBlock() -> llvm::BasicBlock* {
+  synthetic_block_ = llvm::BasicBlock::Create(llvm_context(), "", function_);
+  return synthetic_block_;
+}
+
+auto FunctionContext::FinishInitialization(SemIR::TypeId type_id,
+                                           SemIR::NodeId dest_id,
+                                           SemIR::NodeId source_id) -> void {
+  switch (SemIR::GetInitializingRepresentation(semantics_ir(), type_id).kind) {
+    case SemIR::InitializingRepresentation::None:
+    case SemIR::InitializingRepresentation::InPlace:
+      break;
+    case SemIR::InitializingRepresentation::ByCopy:
+      CopyValue(type_id, source_id, dest_id);
+      break;
+  }
+}
+
+auto FunctionContext::CopyValue(SemIR::TypeId type_id, SemIR::NodeId source_id,
+                                SemIR::NodeId dest_id) -> void {
+  switch (auto rep = SemIR::GetValueRepresentation(semantics_ir(), type_id);
+          rep.kind) {
+    case SemIR::ValueRepresentation::None:
+      break;
+    case SemIR::ValueRepresentation::Copy:
+      builder().CreateStore(GetLocalLoaded(source_id), GetLocal(dest_id));
+      break;
+    case SemIR::ValueRepresentation::Pointer: {
+      const auto& layout = llvm_module().getDataLayout();
+      auto* type = GetType(type_id);
+      // TODO: Compute known alignment of the source and destination, which may
+      // be greater than the alignment computed by LLVM.
+      auto align = layout.getABITypeAlign(type);
+
+      // TODO: Attach !tbaa.struct metadata indicating which portions of the
+      // type we actually need to copy and which are padding.
+      builder().CreateMemCpy(GetLocal(dest_id), align, GetLocal(source_id),
+                             align, layout.getTypeAllocSize(type));
+      break;
+    }
+    case SemIR::ValueRepresentation::Custom:
+      CARBON_FATAL() << "TODO: Add support for CopyValue with custom value rep";
+  }
+}
+
+auto FunctionContext::GetLocalLoaded(SemIR::NodeId node_id) -> llvm::Value* {
+  auto* value = GetLocal(node_id);
+  if (llvm::isa<llvm::AllocaInst, llvm::GetElementPtrInst>(value)) {
+    auto* load_type = GetType(semantics_ir().GetNode(node_id).type_id());
+    return builder().CreateLoad(load_type, value);
+  } else {
+    // No load is needed.
+    return value;
+  }
+}
+
+}  // namespace Carbon::Lower