Adding control flow simplification pass to compensate for lack of phi.

src/alloy/compiler/compiler_passes.h

@@ -11,8 +11,9 @@
 #define ALLOY_COMPILER_COMPILER_PASSES_H_
 
 #include <alloy/compiler/passes/constant_propagation_pass.h>
-#include <alloy/compiler/passes/control_flow_analysis_pass.h>
 #include <alloy/compiler/passes/context_promotion_pass.h>
+#include <alloy/compiler/passes/control_flow_analysis_pass.h>
+#include <alloy/compiler/passes/control_flow_simplification_pass.h>
 #include <alloy/compiler/passes/data_flow_analysis_pass.h>
 #include <alloy/compiler/passes/dead_code_elimination_pass.h>
 //#include <alloy/compiler/passes/dead_store_elimination_pass.h>

src/alloy/compiler/passes/control_flow_simplification_pass.cc

@@ -0,0 +1,60 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2014 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include <alloy/compiler/passes/control_flow_simplification_pass.h>
+
+#include <alloy/backend/backend.h>
+#include <alloy/compiler/compiler.h>
+#include <alloy/runtime/runtime.h>
+
+namespace alloy {
+namespace compiler {
+namespace passes {
+
+// TODO(benvanik): remove when enums redefined.
+using namespace alloy::hir;
+
+using alloy::hir::Edge;
+using alloy::hir::HIRBuilder;
+
+ControlFlowSimplificationPass::ControlFlowSimplificationPass()
+    : CompilerPass() {}
+
+ControlFlowSimplificationPass::~ControlFlowSimplificationPass() {}
+
+int ControlFlowSimplificationPass::Run(HIRBuilder* builder) {
+  SCOPE_profile_cpu_f("alloy");
+
+  // Walk backwards and merge blocks if possible.
+  bool merged_any = false;
+  auto block = builder->last_block();
+  while (block) {
+    auto prev_block = block->prev;
+    const uint32_t expected = Edge::DOMINATES | Edge::UNCONDITIONAL;
+    if (block->incoming_edge_head &&
+        (block->incoming_edge_head->flags & expected) == expected) {
+      // Dominated by the incoming block.
+      // If that block comes immediately before us then we can merge the
+      // two blocks (assuming it's not a volatile instruction like Trap).
+      if (block->prev == block->incoming_edge_head->src &&
+          block->prev->instr_tail &&
+          !(block->prev->instr_tail->opcode->flags & OPCODE_FLAG_VOLATILE)) {
+        builder->MergeAdjacentBlocks(block->prev, block);
+        merged_any = true;
+      }
+    }
+    block = prev_block;
+  }
+
+  return 0;
+}
+
+}  // namespace passes
+}  // namespace compiler
+}  // namespace alloy

src/alloy/compiler/passes/control_flow_simplification_pass.h

@@ -0,0 +1,33 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2014 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef ALLOY_COMPILER_PASSES_CONTROL_FLOW_SIMPLIFICATION_PASS_H_
+#define ALLOY_COMPILER_PASSES_CONTROL_FLOW_SIMPLIFICATION_PASS_H_
+
+#include <alloy/compiler/compiler_pass.h>
+
+namespace alloy {
+namespace compiler {
+namespace passes {
+
+class ControlFlowSimplificationPass : public CompilerPass {
+ public:
+  ControlFlowSimplificationPass();
+  ~ControlFlowSimplificationPass() override;
+
+  int Run(hir::HIRBuilder* builder) override;
+
+ private:
+};
+
+}  // namespace passes
+}  // namespace compiler
+}  // namespace alloy
+
+#endif  // ALLOY_COMPILER_PASSES_CONTROL_FLOW_SIMPLIFICATION_PASS_H_

src/alloy/compiler/passes/register_allocation_pass.cc

@@ -320,8 +320,7 @@ bool RegisterAllocationPass::TryAllocateRegister(Value* value) {
   return false;
 }
 
-bool RegisterAllocationPass::SpillOneRegister(HIRBuilder* builder,
-                                              Block* block,
+bool RegisterAllocationPass::SpillOneRegister(HIRBuilder* builder, Block* block,
                                               TypeName required_type) {
   // Get the set that we will be picking from.
   RegisterSetUsage* usage_set;

src/alloy/compiler/passes/sources.gypi

@@ -7,6 +7,8 @@
     'context_promotion_pass.h',
     'control_flow_analysis_pass.cc',
     'control_flow_analysis_pass.h',
+    'control_flow_simplification_pass.cc',
+    'control_flow_simplification_pass.h',
     'data_flow_analysis_pass.cc',
     'data_flow_analysis_pass.h',
     'dead_code_elimination_pass.cc',

src/alloy/frontend/ppc/ppc_translator.cc

@@ -43,7 +43,10 @@ PPCTranslator::PPCTranslator(PPCFrontend* frontend) : frontend_(frontend) {
 
   bool validate = FLAGS_validate_hir;
 
-  // Build the CFG first.
+  // Merge blocks early. This will let us use more context in other passes.
+  // The CFG is required for simplification and dirtied by it.
+  compiler_->AddPass(std::make_unique<passes::ControlFlowAnalysisPass>());
+  compiler_->AddPass(std::make_unique<passes::ControlFlowSimplificationPass>());
   compiler_->AddPass(std::make_unique<passes::ControlFlowAnalysisPass>());
 
   // Passes are executed in the order they are added. Multiple of the same

src/alloy/hir/hir_builder.cc

@@ -436,6 +436,88 @@ void HIRBuilder::AddEdge(Block* src, Block* dest, uint32_t flags) {
   dest->incoming_edge_head = edge;
 }
 
+void HIRBuilder::MergeAdjacentBlocks(Block* left, Block* right) {
+  assert_true(left->next == right && right->prev == left);
+  assert_true(!right->incoming_edge_head ||
+              right->incoming_edge_head->flags & Edge::DOMINATES);
+
+  // If the left block ends with a branch to the right block, drop it.
+  if (left->instr_tail &&
+      left->instr_tail->opcode->flags & OPCODE_FLAG_BRANCH) {
+    auto sig = left->instr_tail->opcode->signature;
+    if (GET_OPCODE_SIG_TYPE_SRC1(sig) == OPCODE_SIG_TYPE_L) {
+      if (left->instr_tail->src1.label->block == right) {
+        left->instr_tail->Remove();
+      }
+    }
+    if (GET_OPCODE_SIG_TYPE_SRC2(sig) == OPCODE_SIG_TYPE_L) {
+      if (left->instr_tail->src2.label->block == right) {
+        left->instr_tail->Remove();
+      }
+    }
+  }
+
+  // Walk through the right instructions and shift each one back into the left.
+  while (right->instr_head) {
+    auto instr = right->instr_head;
+    auto next = instr->next;
+
+    // Link into block list.
+    instr->next = nullptr;
+    instr->prev = left->instr_tail;
+    if (left->instr_tail) {
+      left->instr_tail->next = instr;
+    } else {
+      left->instr_head = left->instr_tail = instr;
+    }
+    left->instr_tail = instr;
+
+    // Unlink from old block list;
+    right->instr_head = next;
+    if (right->instr_tail == instr) {
+      right->instr_tail = nullptr;
+    }
+    if (next) {
+      next->prev = nullptr;
+    }
+
+    // Update state.
+    instr->block = left;
+  }
+
+  // Move/remove labels.
+  // We only need to preserve named labels.
+  while (right->label_head) {
+    auto label = right->label_head;
+    if (label->name) {
+      // Label is named - move it.
+      label->block = left;
+      label->prev = left->label_tail;
+      if (left->label_tail) {
+        left->label_tail->next = label;
+      }
+      left->label_tail = label;
+      if (!left->label_head) {
+        left->label_head = label;
+      }
+    }
+    right->label_head = label->next;
+    if (right->label_tail == label) {
+      right->label_tail = nullptr;
+    }
+    label->next = nullptr;
+  }
+
+  // Remove the right block from the block list.
+  left->next = right->next;
+  if (right->next) {
+    right->next->prev = left;
+  }
+  if (block_tail_ == right) {
+    block_tail_ = left;
+  }
+}
+
 Block* HIRBuilder::AppendBlock() {
   Block* block = arena_->Alloc<Block>();
   block->arena = arena_;

src/alloy/hir/hir_builder.h

@@ -61,6 +61,7 @@ class HIRBuilder {
   void ResetLabelTags();
 
   void AddEdge(Block* src, Block* dest, uint32_t flags);
+  void MergeAdjacentBlocks(Block* left, Block* right);
 
   // static allocations:
   // Value* AllocStatic(size_t length);

src/alloy/hir/opcodes.inl

@@ -108,13 +108,13 @@ DEFINE_OPCODE(
     OPCODE_BRANCH_TRUE,
     "branch_true",
     OPCODE_SIG_X_V_L,
-    OPCODE_FLAG_BRANCH)
+    OPCODE_FLAG_BRANCH | OPCODE_FLAG_VOLATILE)
 
 DEFINE_OPCODE(
     OPCODE_BRANCH_FALSE,
     "branch_false",
     OPCODE_SIG_X_V_L,
-    OPCODE_FLAG_BRANCH)
+    OPCODE_FLAG_BRANCH | OPCODE_FLAG_VOLATILE)
 
 DEFINE_OPCODE(
     OPCODE_ASSIGN,

src/xenia/kernel/xboxkrnl_rtl.cc

@@ -663,8 +663,6 @@ spin:
 
 SHIM_CALL RtlEnterCriticalSection_shim(
     PPCContext* ppc_state, KernelState* state) {
-  SCOPE_profile_cpu_f("kernel");
-
   uint32_t cs_ptr = SHIM_GET_ARG_32(0);
 
   // XELOGD("RtlEnterCriticalSection(%.8X)", cs_ptr);