fix: Restore previous version of divergence PR.

src/shader_recompiler/frontend/control_flow_graph.cpp

@@ -148,47 +148,46 @@ void CFG::EmitDivergenceLabels() {
         const size_t end_index = GetIndex(end);
 
         s32 curr_begin = -1;
+        s32 last_exec_idx = -1;
         for (size_t index = GetIndex(start); index < end_index; index++) {
             const auto& inst = inst_list[index];
-            const bool is_close = is_close_scope(inst);
-            if ((is_close || index == end_index - 1) && curr_begin != -1) {
-                // If there are no instructions inside scope don't do anything.
-                if (index - curr_begin == 1) {
+            if (curr_begin != -1) {
+                // Keep note of the last instruction that does not ignore exec, so we know where
+                // to end the divergence block without impacting trailing instructions that do.
+                if (!IgnoresExecMask(inst)) {
+                    last_exec_idx = index;
+                }
+                // Consider a close scope on certain instruction types or at the last instruction
+                // before the next label.
+                if (is_close_scope(inst) || index == end_index - 1) {
+                    // Only insert a scope if, since the open-scope instruction, there is at least
+                    // one instruction that does not ignore exec.
+                    if (index - curr_begin > 1 && last_exec_idx != -1) {
+                        // Add a label to the instruction right after the open scope call.
+                        // It is the start of a new basic block.
+                        const auto& save_inst = inst_list[curr_begin];
+                        AddLabel(index_to_pc[curr_begin] + save_inst.length);
+                        // Add a label to the close scope instruction.
+                        // There are 3 cases where we need to close a scope.
+                        // * Close scope instruction inside the block
+                        // * Close scope instruction at the end of the block (cbranch or endpgm)
+                        // * Normal instruction at the end of the block
+                        // If the instruction we want to close the scope at is at the end of the
+                        // block, we do not need to insert a new label.
+                        if (last_exec_idx != end_index - 1) {
+                            // Add the label after the last instruction affected by exec.
+                            const auto& last_exec_inst = inst_list[last_exec_idx];
+                            AddLabel(index_to_pc[last_exec_idx] + last_exec_inst.length);
+                        }
+                    }
+                    // Reset scope begin.
                     curr_begin = -1;
-                    continue;
                 }
-                // If all instructions in the scope ignore exec masking, we shouldn't insert a
-                // scope.
-                const auto start = inst_list.begin() + curr_begin + 1;
-                if (!std::ranges::all_of(start, inst_list.begin() + index, IgnoresExecMask)) {
-                    // Determine the last instruction affected by the exec mask, so that any
-                    // trailing instructions not affected can be excluded from the scope.
-                    s32 curr_end = index;
-                    while (IgnoresExecMask(inst_list[curr_end - 1])) {
-                        --curr_end;
-                    }
-                    // Add a label to the instruction right after the open scope call.
-                    // It is the start of a new basic block.
-                    const auto& save_inst = inst_list[curr_begin];
-                    const Label label = index_to_pc[curr_begin] + save_inst.length;
-                    AddLabel(label);
-                    // Add a label to the close scope instruction.
-                    // There are 3 cases where we need to close a scope.
-                    // * Close scope instruction inside the block
-                    // * Close scope instruction at the end of the block (cbranch or endpgm)
-                    // * Normal instruction at the end of the block
-                    // For the last case we must NOT add a label as that would cause
-                    // the instruction to be separated into its own basic block.
-                    if (curr_end != end_index - 1) {
-                        AddLabel(index_to_pc[curr_end]);
-                    }
-                }
-                // Reset scope begin.
-                curr_begin = -1;
             }
             // Mark a potential start of an exec scope.
             if (is_open_scope(inst)) {
                 curr_begin = index;
+                last_exec_idx = -1;
             }
         }
     }