sema: add internStrLit, STR handler, Pass 1b ipForceIntern

Add string literal interning for comptime ZIR_INST_STR handling:
- internStrLit() creates 4 IP entries (type_array_big, bytes,
  type_pointer, ptr_uav) matching Zig's addStrLit + uavRef.
- Wire into STR instruction handler in comptime context.

Fix Pass 1b type_pointer deduplication: use ipForceIntern instead
of internPtrConst to match Zig's sharded IP behavior where
dedup doesn't happen across shards.

Add ipForceIntern to intern_pool (bypasses dedup, always creates
new entry). Also add verbose_intern_pool output for ptr_uav entries.

Reduces neghf2 IP gap from ~63 to 54 entries.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

stage0/intern_pool.c

@@ -729,6 +729,12 @@ InternPoolIndex ipIntern(InternPool* ip, InternPoolKey key) {
     return new_index;
 }
 
+InternPoolIndex ipForceIntern(InternPool* ip, InternPoolKey key) {
+    uint32_t new_index = ip->items_len;
+    ipAppendItem(ip, key);
+    return new_index;
+}
+
 InternPoolKey ipIndexToKey(const InternPool* ip, InternPoolIndex index) {
     InternPoolKey key;
     memset(&key, 0, sizeof(key));

stage0/intern_pool.h

@@ -458,6 +458,7 @@ typedef struct {
 InternPool ipInit(void);
 void ipDeinit(InternPool* ip);
 InternPoolIndex ipIntern(InternPool* ip, InternPoolKey key);
+InternPoolIndex ipForceIntern(InternPool* ip, InternPoolKey key);
 InternPoolKey ipIndexToKey(const InternPool* ip, InternPoolIndex index);
 InternPoolIndex ipTypeOf(const InternPool* ip, InternPoolIndex index);
 

stage0/sema.h

@@ -291,6 +291,15 @@ typedef struct Sema {
     // File index into s_loaded_modules[] for this sema's module.
     // Set by analyzeNavValC / semaAnalyze. UINT32_MAX = unknown.
     uint32_t file_idx;
+    // Comptime return alloc tracking for result-location function evaluation.
+    // Used by zirRetPtr/zirRetLoad/zirOptEuBasePtrInit/zirStoreNode in
+    // comptime context. Set by comptimeFieldCall.
+    // Ported from Sema.zig ComptimeAlloc / retPtrComptime.
+    InternPoolIndex comptime_ret_ptr; // ptr_comptime_alloc IP index
+    InternPoolIndex comptime_ret_val; // stored return value
+    InternPoolIndex comptime_inner_type; // inner type after optional unwrap
+    InternPoolIndex comptime_field_type; // union field type for struct init
+    uint32_t comptime_field_idx; // union field index for struct init
 } Sema;
 
 #define SEMA_DEFAULT_BRANCH_QUOTA 1000

stage0/verbose_intern_pool.c

@@ -114,6 +114,10 @@ void verboseIpPrint(FILE* out, const InternPool* ip) {
                 key.data.int_type.signedness ? 'i' : 'u',
                 key.data.int_type.bits);
             break;
+        case IP_KEY_ARRAY_TYPE:
+            fprintf(out, " len=%" PRIu64 " child=%u", key.data.array_type.len,
+                key.data.array_type.child);
+            break;
         case IP_KEY_STRUCT_TYPE:
             fprintf(out, " hash=%u", key.data.struct_type);
             break;