r600g/sb: fix issue with DCE between GVN and GCM (v2)

We can't perform DCE using the liveness pass between GVN and GCM
because it relies on the correct schedule, but GVN doesn't care about
preserving correctness - it's rescheduled later by GCM.

This patch makes dce_cleanup pass perform simple DCE
between GVN and GCM instead of relying on liveness pass.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=70088

Signed-off-by: Vadim Girlin <vadimgirlin@gmail.com>

src/gallium/drivers/r600/sb/sb_core.cpp

@@ -184,6 +184,8 @@ int r600_sb_bytecode_process(struct r600_context *rctx,
 		SB_RUN_PASS(psi_ops,		1);
 
 	SB_RUN_PASS(liveness,			0);
+
+	sh->dce_flags = DF_REMOVE_DEAD | DF_EXPAND;
 	SB_RUN_PASS(dce_cleanup,		0);
 	SB_RUN_PASS(def_use,			0);
 
@@ -201,9 +203,10 @@ int r600_sb_bytecode_process(struct r600_context *rctx,
 
 	SB_RUN_PASS(gvn,				1);
 
-	SB_RUN_PASS(liveness,			0);
+	SB_RUN_PASS(def_use,			1);
+
+	sh->dce_flags = DF_REMOVE_DEAD | DF_REMOVE_UNUSED;
 	SB_RUN_PASS(dce_cleanup,		1);
-	SB_RUN_PASS(def_use,			0);
 
 	SB_RUN_PASS(ra_split,			0);
 	SB_RUN_PASS(def_use,			0);
@@ -217,6 +220,9 @@ int r600_sb_bytecode_process(struct r600_context *rctx,
 	sh->compute_interferences = true;
 	SB_RUN_PASS(liveness,			0);
 
+	sh->dce_flags = DF_REMOVE_DEAD;
+	SB_RUN_PASS(dce_cleanup,		1);
+
 	SB_RUN_PASS(ra_coalesce,		1);
 	SB_RUN_PASS(ra_init,			1);
 

src/gallium/drivers/r600/sb/sb_dce_cleanup.cpp

@@ -56,7 +56,8 @@ bool dce_cleanup::visit(cf_node& n, bool enter) {
 		else
 			cleanup_dst(n);
 	} else {
-		if (n.bc.op_ptr->flags & (CF_CLAUSE | CF_BRANCH | CF_LOOP))
+		if ((sh.dce_flags & DF_EXPAND) &&
+				(n.bc.op_ptr->flags & (CF_CLAUSE | CF_BRANCH | CF_LOOP)))
 			n.expand();
 	}
 	return true;
@@ -107,19 +108,20 @@ bool dce_cleanup::visit(region_node& n, bool enter) {
 }
 
 void dce_cleanup::cleanup_dst(node& n) {
-	cleanup_dst_vec(n.dst);
+	if (!cleanup_dst_vec(n.dst) && remove_unused &&
+			!n.dst.empty() && !(n.flags & NF_DONT_KILL) && n.parent)
+		n.remove();
 }
 
 bool dce_cleanup::visit(container_node& n, bool enter) {
-	if (enter) {
+	if (enter)
 		cleanup_dst(n);
-	} else {
-
-	}
 	return true;
 }
 
-void dce_cleanup::cleanup_dst_vec(vvec& vv) {
+bool dce_cleanup::cleanup_dst_vec(vvec& vv) {
+	bool alive = false;
+
 	for (vvec::iterator I = vv.begin(), E = vv.end(); I != E; ++I) {
 		value* &v = *I;
 		if (!v)
@@ -128,9 +130,13 @@ void dce_cleanup::cleanup_dst_vec(vvec& vv) {
 		if (v->gvn_source && v->gvn_source->is_dead())
 			v->gvn_source = NULL;
 
-		if (v->is_dead())
+		if (v->is_dead() || (remove_unused && !v->is_rel() && !v->uses))
 			v = NULL;
+		else
+			alive = true;
 	}
+
+	return alive;
 }
 
 } // namespace r600_sb

src/gallium/drivers/r600/sb/sb_pass.h

@@ -119,9 +119,12 @@ public:
 class dce_cleanup : public vpass {
 	using vpass::visit;
 
+	bool remove_unused;
+
 public:
 
-	dce_cleanup(shader &s) : vpass(s) {}
+	dce_cleanup(shader &s) : vpass(s),
+		remove_unused(s.dce_flags & DF_REMOVE_UNUSED) {}
 
 	virtual bool visit(node &n, bool enter);
 	virtual bool visit(alu_group_node &n, bool enter);
@@ -135,7 +138,7 @@ public:
 private:
 
 	void cleanup_dst(node &n);
-	void cleanup_dst_vec(vvec &vv);
+	bool cleanup_dst_vec(vvec &vv);
 
 };
 

src/gallium/drivers/r600/sb/sb_shader.h

@@ -71,6 +71,16 @@ enum chunk_flags {
 	RCF_PREALLOC = (1 << 4)
 };
 
+enum dce_flags {
+	DF_REMOVE_DEAD  = (1 << 0),
+	DF_REMOVE_UNUSED = (1 << 1),
+	DF_EXPAND = (1 << 2),
+};
+
+inline dce_flags operator |(dce_flags l, dce_flags r) {
+	return (dce_flags)((unsigned)l|(unsigned)r);
+}
+
 inline chunk_flags operator |(chunk_flags l, chunk_flags r) {
 	return (chunk_flags)((unsigned)l|(unsigned)r);
 }
@@ -297,6 +307,8 @@ public:
 
 	unsigned ngpr, nstack;
 
+	unsigned dce_flags;
+
 	shader(sb_context &sctx, shader_target t, unsigned id);
 
 	~shader();