[Mesa-dev] [PATCH] r600g/sb: fix issue with DCE between GVN and GCM (v2)

[Vadim Girlin]

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 at gmail.com>
---
 src/gallium/drivers/r600/sb/sb_core.cpp        | 10 ++++++++--
 src/gallium/drivers/r600/sb/sb_dce_cleanup.cpp | 22 ++++++++++++++--------
 src/gallium/drivers/r600/sb/sb_pass.h          |  7 +++++--
 src/gallium/drivers/r600/sb/sb_shader.h        | 12 ++++++++++++
 4 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/src/gallium/drivers/r600/sb/sb_core.cpp b/src/gallium/drivers/r600/sb/sb_core.cpp
index b5dd88e..9fd9d9a 100644
--- a/src/gallium/drivers/r600/sb/sb_core.cpp
+++ b/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);
 
diff --git a/src/gallium/drivers/r600/sb/sb_dce_cleanup.cpp b/src/gallium/drivers/r600/sb/sb_dce_cleanup.cpp
index f879395..79aef91 100644
--- a/src/gallium/drivers/r600/sb/sb_dce_cleanup.cpp
+++ b/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
diff --git a/src/gallium/drivers/r600/sb/sb_pass.h b/src/gallium/drivers/r600/sb/sb_pass.h
index 95d2a20..a3f8515 100644
--- a/src/gallium/drivers/r600/sb/sb_pass.h
+++ b/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);
 
 };
 
diff --git a/src/gallium/drivers/r600/sb/sb_shader.h b/src/gallium/drivers/r600/sb/sb_shader.h
index e515d31..7955bba 100644
--- a/src/gallium/drivers/r600/sb/sb_shader.h
+++ b/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();
-- 
1.8.3.1