an optimization in the jitter for generating more compact code

src/runtime/c/pgf/jit.c

@@ -41,15 +41,12 @@ pgf_jit_finalize_page(GuFinalizer* self)
 	free(fin->page);
 }
 
-static size_t total_size = 0;
-
 static void
 pgf_jit_alloc_page(PgfJitState* state)
 {
 	void *page;
 
 	size_t page_size = getpagesize();
-	total_size += page_size;
 
 	if (posix_memalign(&page, page_size, page_size) != 0) {
 		gu_fatal("Memory allocation failed");
@@ -166,6 +163,9 @@ pgf_jit_predicate(PgfJitState* state,
 		jit_getarg_p(JIT_V1, rs_arg);
 		jit_getarg_p(JIT_V2, st_arg);
 
+		size_t n_hypos = gu_seq_length(absfun->type->hypos);
+
+		if (n_hypos > 0) {
 			if (i+1 < n_funs) {
 				PgfAbsFun* absfun = 
 					gu_buf_get(abscat->functions, PgfAbsFun*, i+1);
@@ -185,7 +185,6 @@ pgf_jit_predicate(PgfJitState* state,
 				jit_finish(pgf_try_else);
 			}
 				
-		size_t n_hypos = gu_seq_length(absfun->type->hypos);
 			for (size_t i = 0; i < n_hypos; i++) {
 				PgfHypo* hypo = gu_seq_index(absfun->type->hypos, PgfHypo, i);
 
@@ -198,7 +197,11 @@ pgf_jit_predicate(PgfJitState* state,
 #ifdef PGF_JIT_DEBUG
 				gu_puts("    CALL ", wtr, err);
 				gu_string_write(hypo->type->cid, wtr, err);
+				if (i+1 < n_hypos) {
 					gu_printf(wtr, err, " L%d\n", label);
+				} else {
+					gu_printf(wtr, err, " COMPLETE\n");
+				}
 #endif
 
 				// compile CALL
@@ -218,12 +221,15 @@ pgf_jit_predicate(PgfJitState* state,
 
 #ifdef PGF_JIT_DEBUG
 				gu_puts("    RET\n", wtr, err);
+				if (i+1 < n_hypos) {
 					gu_printf(wtr, err, "L%d:\n", label++);
+				}
 #endif
 
 				// compile RET
 				jit_ret();
 
+				if (i+1 < n_hypos) {
 					pgf_jit_make_space(state);
 
 					jit_patch_movi(ref,jit_get_label());
@@ -233,8 +239,29 @@ pgf_jit_predicate(PgfJitState* state,
 					st_arg = jit_arg_p();
 					jit_getarg_p(JIT_V1, rs_arg);
 					jit_getarg_p(JIT_V2, st_arg);
+				} else {
+					jit_patch_movi(ref,pgf_complete);
 				}
+			}
+		} else {
+			if (i+1 < n_funs) {
+				PgfAbsFun* absfun = 
+					gu_buf_get(abscat->functions, PgfAbsFun*, i+1);
 
+#ifdef PGF_JIT_DEBUG
+				gu_puts("    TRY_CONSTANT ", wtr, err);
+				gu_string_write(absfun->name, wtr, err);
+				gu_puts("\n", wtr, err);
+#endif
+
+				// compile TRY_CONSTANT
+				jit_prepare(3);
+				jit_movi_p(JIT_V0, absfun);
+				jit_pusharg_p(JIT_V0);
+				jit_pusharg_p(JIT_V2);
+				jit_pusharg_p(JIT_V1);
+				jit_finish(pgf_try_constant);
+			} else {
 #ifdef PGF_JIT_DEBUG
 				gu_puts("    COMPLETE\n", wtr, err);
 #endif
@@ -244,6 +271,7 @@ pgf_jit_predicate(PgfJitState* state,
 				jit_pusharg_p(JIT_V2);
 				jit_pusharg_p(JIT_V1);
 				jit_finish(pgf_complete);
+			}
 
 #ifdef PGF_JIT_DEBUG
 			gu_puts("    RET\n", wtr, err);
@@ -251,6 +279,7 @@ pgf_jit_predicate(PgfJitState* state,
 
 			// compile RET
 			jit_ret();
+		}
 		
 #ifdef PGF_JIT_DEBUG
 		if (i+1 < n_funs) {

src/runtime/c/pgf/reasoner.c

@@ -40,7 +40,7 @@ struct PgfExprState {
 
 typedef struct {
 	// base must be the first field in order to be able to cast
-	// from PgfCombine2State to PgfReasonerState
+	// from PgfCombine1State to PgfReasonerState
 	PgfReasonerState base;
 	GuBuf* exprs;
 	PgfExprState* parent;
@@ -331,6 +331,13 @@ pgf_complete(PgfReasoner* rs, PgfExprState* st)
 	nst->base.continuation(rs, &nst->base);
 }
 
+void
+pgf_try_constant(PgfReasoner* rs, PgfExprState* prev, PgfAbsFun* absfun)
+{
+	pgf_try_else(rs, prev, absfun);
+	pgf_complete(rs, prev);
+}
+
 static PgfExprProb*
 pgf_reasoner_next(PgfReasoner* rs)
 {