From 12818c6fdeec345b4b4c20d9d33e00e10f16bcae Mon Sep 17 00:00:00 2001
From: Ulya Trofimovich <skvadrik@gmail.com>
Date: Sat, 11 Aug 2018 00:13:04 +0100
Subject: [PATCH] Simplified back up / restore of tag actions when mapping TDFA
 states.

---
 re2c/src/dfa/find_state.cc | 34 +++++++++++-----------------------
 re2c/src/dfa/find_state.h  |  3 +--
 re2c/src/dfa/tcmd.h        |  2 --
 3 files changed, 12 insertions(+), 27 deletions(-)

diff --git a/re2c/src/dfa/find_state.cc b/re2c/src/dfa/find_state.cc
index 6a63aac1..9ccffe37 100644
--- a/re2c/src/dfa/find_state.cc
+++ b/re2c/src/dfa/find_state.cc
@@ -40,8 +40,7 @@ kernel_buffers_t::kernel_buffers_t(allocator_t &alc)
 	, y2x(NULL)
 	, x2t(NULL)
 	, indegree(NULL)
-	, actnext(NULL)
-	, actlhs(NULL)
+	, backup_actions(NULL)
 {}
 
 
@@ -106,11 +105,10 @@ void reserve_buffers(kernel_buffers_t &kbufs, allocator_t &alc,
 			m = 2 * n + 1,
 			sz_x2y = 2 * m * sizeof(tagver_t),
 			sz_x2t = m * sizeof(size_t),
-			sz_actnext = n * sizeof(tcmd_t*),
-			sz_actlhs = n * sizeof(tagver_t),
-			sz_indeg = n * sizeof(uint32_t);
+			sz_idg = n * sizeof(uint32_t),
+			sz_act = n * sizeof(tcmd_t);
 
-		char *p = alc.alloct<char>(sz_x2y + sz_x2t + sz_actnext + sz_actlhs + sz_indeg);
+		char *p = alc.alloct<char>(sz_x2y + sz_x2t + sz_idg + sz_act);
 		kbufs.memory = p;
 
 		// point to the center (zero index) of each buffer
@@ -120,11 +118,9 @@ void reserve_buffers(kernel_buffers_t &kbufs, allocator_t &alc,
 		p += sz_x2y;
 		kbufs.x2t = reinterpret_cast<size_t*>(p) + n;
 		p += sz_x2t;
-		kbufs.actnext = reinterpret_cast<tcmd_t**>(p);
-		p += sz_actnext;
-		kbufs.actlhs = reinterpret_cast<tagver_t*>(p);
-		p += sz_actlhs;
 		kbufs.indegree = reinterpret_cast<uint32_t*>(p);
+		p += sz_idg;
+		kbufs.backup_actions = reinterpret_cast<tcmd_t*>(p);
 	}
 }
 
@@ -246,16 +242,12 @@ bool kernels_t::operator()(const kernel_t *x, const kernel_t *y)
 	}
 
 	// we have bijective mapping; now try to create list of commands
-	tcmd_t **actnext = buffers.actnext, *a, **pa, *copy = NULL;
-	tagver_t *actlhs = buffers.actlhs;
+	tcmd_t *b1 = buffers.backup_actions, *b2 = b1, *a, **pa, *copy = NULL;
 
 	// backup 'save' commands: if topsort finds cycles, this mapping
 	// will be rejected and we'll have to revert all changes
-	size_t nact = 0;
-	for (a = *pacts; a; a = a->next) {
-		actnext[nact] = a;
-		actlhs[nact] = a->lhs;
-		++nact;
+	for (b2->next = a = *pacts; a; a = a->next) {
+		*++b2 = *a;
 	}
 
 	// fix LHS of 'save' commands to reuse old version
@@ -287,13 +279,9 @@ bool kernels_t::operator()(const kernel_t *x, const kernel_t *y)
 
 	// in case of cycles restore 'save' commands and fail
 	if (nontrivial_cycles) {
-		pa = pacts;
-		for (size_t i = 0; i < nact; ++i) {
-			*pa = a = actnext[i];
-			a->lhs = actlhs[i];
-			pa = &a->next;
+		for (*pacts = a = b1->next; a; a = a->next) {
+			*a = *++b1;
 		}
-		*pa = NULL;
 	}
 
 	return !nontrivial_cycles;
diff --git a/re2c/src/dfa/find_state.h b/re2c/src/dfa/find_state.h
index bb0144fd..403d0ace 100644
--- a/re2c/src/dfa/find_state.h
+++ b/re2c/src/dfa/find_state.h
@@ -44,8 +44,7 @@ struct kernel_buffers_t
 	tagver_t *y2x;
 	size_t *x2t;
 	uint32_t *indegree;
-	tcmd_t **actnext;
-	tagver_t *actlhs;
+	tcmd_t *backup_actions;
 
 	explicit kernel_buffers_t(allocator_t &alc);
 };
diff --git a/re2c/src/dfa/tcmd.h b/re2c/src/dfa/tcmd.h
index 88d12fa4..a2203f28 100644
--- a/re2c/src/dfa/tcmd.h
+++ b/re2c/src/dfa/tcmd.h
@@ -6,7 +6,6 @@
 
 #include "src/dfa/tagtree.h"
 #include "src/re/tag.h"
-#include "src/util/forbid_copy.h"
 #include "src/util/lookup.h"
 #include "src/util/slab_allocator.h"
 
@@ -26,7 +25,6 @@ struct tcmd_t
 	static bool iscopy(const tcmd_t *x);
 	static bool isset(const tcmd_t *x);
 	static bool isadd(const tcmd_t *x);
-	FORBID_COPY(tcmd_t);
 };
 
 typedef uint32_t tcid_t;
-- 
2.40.0