control_flow: Address feedback.

src/video_core/shader/control_flow.cpp

@@ -4,6 +4,7 @@
 
 #include <list>
 #include <map>
+#include <stack>
 #include <unordered_map>
 #include <unordered_set>
 #include <vector>
@@ -20,68 +21,18 @@ using Tegra::Shader::OpCode;
 
 constexpr s32 unassigned_branch = -2;
 
-/**
- * 'ControlStack' represents a static stack of control jumps such as SSY and PBK
- * stacks in Maxwell.
- **/
-struct ControlStack {
-    static constexpr std::size_t stack_fixed_size = 20;
-    std::array<u32, stack_fixed_size> stack{};
-    u32 index{};
-
-    bool Compare(const ControlStack& cs) const {
-        if (index != cs.index) {
-            return false;
-        }
-        return std::memcmp(stack.data(), cs.stack.data(), index * sizeof(u32)) == 0;
-    }
-
-    /// This compare just compares the top of the stack against one another
-    bool SoftCompare(const ControlStack& cs) const {
-        if (index == 0 || cs.index == 0) {
-            return index == cs.index;
-        }
-        return Top() == cs.Top();
-    }
-
-    u32 Size() const {
-        return index;
-    }
-
-    u32 Top() const {
-        return stack[index - 1];
-    }
-
-    bool Push(u32 address) {
-        if (index >= stack.size()) {
-            return false;
-        }
-        stack[index] = address;
-        index++;
-        return true;
-    }
-
-    bool Pop() {
-        if (index == 0) {
-            return false;
-        }
-        index--;
-        return true;
-    }
-};
-
 struct Query {
     u32 address{};
-    ControlStack ssy_stack{};
-    ControlStack pbk_stack{};
+    std::stack<u32> ssy_stack{};
+    std::stack<u32> pbk_stack{};
 };
 
 struct BlockStack {
     BlockStack() = default;
     BlockStack(const BlockStack& b) = default;
     BlockStack(const Query& q) : ssy_stack{q.ssy_stack}, pbk_stack{q.pbk_stack} {}
-    ControlStack ssy_stack{};
-    ControlStack pbk_stack{};
+    std::stack<u32> ssy_stack{};
+    std::stack<u32> pbk_stack{};
 };
 
 struct BlockBranchInfo {
@@ -144,13 +95,13 @@ struct ParseInfo {
     u32 end_address{};
 };
 
-BlockInfo* CreateBlockInfo(CFGRebuildState& state, u32 start, u32 end) {
+BlockInfo& CreateBlockInfo(CFGRebuildState& state, u32 start, u32 end) {
     auto& it = state.block_info.emplace_back();
     it.start = start;
     it.end = end;
     const u32 index = static_cast<u32>(state.block_info.size() - 1);
     state.registered.insert({start, index});
-    return &it;
+    return it;
 }
 
 Pred GetPredicate(u32 index, bool negated) {
@@ -174,16 +125,17 @@ enum class ParseResult : u32 {
     AbnormalFlow,
 };
 
-ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info) {
+std::pair<ParseResult, ParseInfo> ParseCode(CFGRebuildState& state, u32 address) {
     u32 offset = static_cast<u32>(address);
     const u32 end_address = static_cast<u32>(state.program_size / sizeof(Instruction));
+    ParseInfo parse_info{};
 
-    const auto insert_label = ([](CFGRebuildState& state, u32 address) {
-        auto pair = state.labels.emplace(address);
+    const auto insert_label = [](CFGRebuildState& state, u32 address) {
+        const auto pair = state.labels.emplace(address);
         if (pair.second) {
             state.inspect_queries.push_back(address);
         }
-    });
+    };
 
     while (true) {
         if (offset >= end_address) {
@@ -229,11 +181,11 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
             parse_info.branch_info.ignore = false;
             parse_info.end_address = offset;
 
-            return ParseResult::ControlCaught;
+            return {ParseResult::ControlCaught, parse_info};
         }
         case OpCode::Id::BRA: {
             if (instr.bra.constant_buffer != 0) {
-                return ParseResult::AbnormalFlow;
+                return {ParseResult::AbnormalFlow, parse_info};
             }
             const auto pred_index = static_cast<u32>(instr.pred.pred_index);
             parse_info.branch_info.condition.predicate =
@@ -248,7 +200,7 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
                 offset++;
                 continue;
             }
-            u32 branch_offset = offset + instr.bra.GetBranchTarget();
+            const u32 branch_offset = offset + instr.bra.GetBranchTarget();
             if (branch_offset == 0) {
                 parse_info.branch_info.address = exit_branch;
             } else {
@@ -261,10 +213,9 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
             parse_info.branch_info.ignore = false;
             parse_info.end_address = offset;
 
-            return ParseResult::ControlCaught;
+            return {ParseResult::ControlCaught, parse_info};
         }
         case OpCode::Id::SYNC: {
-            parse_info.branch_info.condition;
             const auto pred_index = static_cast<u32>(instr.pred.pred_index);
             parse_info.branch_info.condition.predicate =
                 GetPredicate(pred_index, instr.negate_pred != 0);
@@ -285,10 +236,9 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
             parse_info.branch_info.ignore = false;
             parse_info.end_address = offset;
 
-            return ParseResult::ControlCaught;
+            return {ParseResult::ControlCaught, parse_info};
         }
         case OpCode::Id::BRK: {
-            parse_info.branch_info.condition;
             const auto pred_index = static_cast<u32>(instr.pred.pred_index);
             parse_info.branch_info.condition.predicate =
                 GetPredicate(pred_index, instr.negate_pred != 0);
@@ -309,10 +259,9 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
             parse_info.branch_info.ignore = false;
             parse_info.end_address = offset;
 
-            return ParseResult::ControlCaught;
+            return {ParseResult::ControlCaught, parse_info};
         }
         case OpCode::Id::KIL: {
-            parse_info.branch_info.condition;
             const auto pred_index = static_cast<u32>(instr.pred.pred_index);
             parse_info.branch_info.condition.predicate =
                 GetPredicate(pred_index, instr.negate_pred != 0);
@@ -333,7 +282,7 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
             parse_info.branch_info.ignore = false;
             parse_info.end_address = offset;
 
-            return ParseResult::ControlCaught;
+            return {ParseResult::ControlCaught, parse_info};
         }
         case OpCode::Id::SSY: {
             const u32 target = offset + instr.bra.GetBranchTarget();
@@ -348,7 +297,7 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
             break;
         }
         case OpCode::Id::BRX: {
-            return ParseResult::AbnormalFlow;
+            return {ParseResult::AbnormalFlow, parse_info};
         }
         default:
             break;
@@ -360,7 +309,7 @@ ParseResult ParseCode(CFGRebuildState& state, u32 address, ParseInfo& parse_info
     parse_info.branch_info.is_sync = false;
     parse_info.branch_info.is_brk = false;
     parse_info.end_address = offset - 1;
-    return ParseResult::BlockEnd;
+    return {ParseResult::BlockEnd, parse_info};
 }
 
 bool TryInspectAddress(CFGRebuildState& state) {
@@ -377,10 +326,10 @@ bool TryInspectAddress(CFGRebuildState& state) {
     case BlockCollision::Inside: {
         // This case is the tricky one:
         // We need to Split the block in 2 sepparate blocks
-        auto it = search_result.second;
-        BlockInfo* block_info = CreateBlockInfo(state, address, it->end);
+        const auto it = search_result.second;
+        BlockInfo& block_info = CreateBlockInfo(state, address, it->end);
         it->end = address - 1;
-        block_info->branch = it->branch;
+        block_info.branch = it->branch;
         BlockBranchInfo forward_branch{};
         forward_branch.address = address;
         forward_branch.ignore = true;
@@ -390,15 +339,14 @@ bool TryInspectAddress(CFGRebuildState& state) {
     default:
         break;
     }
-    ParseInfo parse_info;
-    const ParseResult parse_result = ParseCode(state, address, parse_info);
+    const auto [parse_result, parse_info] = ParseCode(state, address);
     if (parse_result == ParseResult::AbnormalFlow) {
         // if it's AbnormalFlow, we end it as false, ending the CFG reconstruction
         return false;
     }
 
-    BlockInfo* block_info = CreateBlockInfo(state, address, parse_info.end_address);
-    block_info->branch = parse_info.branch_info;
+    BlockInfo& block_info = CreateBlockInfo(state, address, parse_info.end_address);
+    block_info.branch = parse_info.branch_info;
     if (parse_info.branch_info.condition.IsUnconditional()) {
         return true;
     }
@@ -409,14 +357,15 @@ bool TryInspectAddress(CFGRebuildState& state) {
 }
 
 bool TryQuery(CFGRebuildState& state) {
-    const auto gather_labels = ([](ControlStack& cc, std::map<u32, u32>& labels, BlockInfo& block) {
+    const auto gather_labels = [](std::stack<u32>& cc, std::map<u32, u32>& labels,
+                                  BlockInfo& block) {
         auto gather_start = labels.lower_bound(block.start);
         const auto gather_end = labels.upper_bound(block.end);
         while (gather_start != gather_end) {
-            cc.Push(gather_start->second);
+            cc.push(gather_start->second);
             gather_start++;
         }
-    });
+    };
     if (state.queries.empty()) {
         return false;
     }
@@ -428,9 +377,8 @@ bool TryQuery(CFGRebuildState& state) {
     // consumes a label. Schedule new queries accordingly
     if (block.visited) {
         BlockStack& stack = state.stacks[q.address];
-        const bool all_okay =
-            (stack.ssy_stack.Size() == 0 || q.ssy_stack.Compare(stack.ssy_stack)) &&
-            (stack.pbk_stack.Size() == 0 || q.pbk_stack.Compare(stack.pbk_stack));
+        const bool all_okay = (stack.ssy_stack.size() == 0 || q.ssy_stack == stack.ssy_stack) &&
+                              (stack.pbk_stack.size() == 0 || q.pbk_stack == stack.pbk_stack);
         state.queries.pop_front();
         return all_okay;
     }
@@ -447,15 +395,15 @@ bool TryQuery(CFGRebuildState& state) {
     Query conditional_query{q2};
     if (block.branch.is_sync) {
         if (block.branch.address == unassigned_branch) {
-            block.branch.address = conditional_query.ssy_stack.Top();
+            block.branch.address = conditional_query.ssy_stack.top();
         }
-        conditional_query.ssy_stack.Pop();
+        conditional_query.ssy_stack.pop();
     }
     if (block.branch.is_brk) {
         if (block.branch.address == unassigned_branch) {
-            block.branch.address = conditional_query.pbk_stack.Top();
+            block.branch.address = conditional_query.pbk_stack.top();
         }
-        conditional_query.pbk_stack.Pop();
+        conditional_query.pbk_stack.pop();
     }
     conditional_query.address = block.branch.address;
     state.queries.push_back(conditional_query);