i965/fs.h: Refactor tests for instructions modifying a register.

There's one instance of a potential behavior change: propagate_constants may
now propagate into a part of a vgrf after a different part of it was
overwritten by a send that returns multiple registers.  I don't think we ever
generate IR that meets that condition, but it's something to note if we bisect
behavior change to this.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

4 files changed, 16 insertions, 34 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index de049d5b1bf..630150dbffd 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -165,12 +165,21 @@ fs_inst::regs_written()
     */
 
    return 1;
 }
 
 bool
+fs_inst::overwrites_reg(const fs_reg &reg)
+{
+   return (reg.file == dst.file &&
+           reg.reg == dst.reg &&
+           reg.reg_offset >= dst.reg_offset  &&
+           reg.reg_offset < dst.reg_offset + regs_written());
+}
+
+bool
 fs_inst::is_tex()
 {
    return (opcode == SHADER_OPCODE_TEX ||
            opcode == FS_OPCODE_TXB ||
            opcode == SHADER_OPCODE_TXD ||
            opcode == SHADER_OPCODE_TXF ||
@@ -1397,15 +1406,13 @@ fs_visitor::propagate_constants()
 	    default:
 	       break;
 	    }
 	 }
 
 	 if (scan_inst->dst.file == GRF &&
-	     scan_inst->dst.reg == inst->dst.reg &&
-	     (scan_inst->dst.reg_offset == inst->dst.reg_offset ||
-	      scan_inst->regs_written() > 1)) {
+             scan_inst->overwrites_reg(inst->dst)) {
 	    break;
 	 }
       }
    }
 
    if (progress)
@@ -1599,22 +1606,14 @@ fs_visitor::register_coalesce()
       bool interfered = false;
 
       for (fs_inst *scan_inst = (fs_inst *)inst->next;
 	   !scan_inst->is_tail_sentinel();
 	   scan_inst = (fs_inst *)scan_inst->next) {
 	 if (scan_inst->dst.file == GRF) {
-	    if (scan_inst->dst.reg == inst->dst.reg &&
-		(scan_inst->dst.reg_offset == inst->dst.reg_offset ||
-		 scan_inst->regs_written() > 1)) {
-	       interfered = true;
-	       break;
-	    }
-	    if (inst->src[0].file == GRF &&
-		scan_inst->dst.reg == inst->src[0].reg &&
-		(scan_inst->dst.reg_offset == inst->src[0].reg_offset ||
-		 scan_inst->regs_written() > 1)) {
+	    if (scan_inst->overwrites_reg(inst->dst) ||
+                scan_inst->overwrites_reg(inst->src[0])) {
 	       interfered = true;
 	       break;
 	    }
 	 }
 
 	 /* The gen6 MATH instruction can't handle source modifiers or
diff --git a/src/mesa/drivers/dri/i965/brw_fs.h b/src/mesa/drivers/dri/i965/brw_fs.h
index deb58d84bee..6e3c46a39ea 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.h
+++ b/src/mesa/drivers/dri/i965/brw_fs.h
@@ -147,12 +147,13 @@ public:
    fs_inst(enum opcode opcode, fs_reg dst, fs_reg src0, fs_reg src1);
    fs_inst(enum opcode opcode, fs_reg dst,
            fs_reg src0, fs_reg src1,fs_reg src2);
 
    bool equals(fs_inst *inst);
    int regs_written();
+   bool overwrites_reg(const fs_reg &reg);
    bool is_tex();
    bool is_math();
 
    enum opcode opcode; /* BRW_OPCODE_* or FS_OPCODE_* */
    fs_reg dst;
    fs_reg src[3];
diff --git a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
index 106964d4843..1870f43feba 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp
@@ -95,29 +95,17 @@ fs_visitor::opt_copy_propagate_local(void *mem_ctx,
 	       progress = true;
 	 }
       }
 
       /* kill the destination from the ACP */
       if (inst->dst.file == GRF) {
-	 int start_offset = inst->dst.reg_offset;
-	 int end_offset = start_offset + inst->regs_written();
-
 	 foreach_list_safe(entry_node, acp) {
 	    acp_entry *entry = (acp_entry *)entry_node;
 
-	    if (entry->dst.file == GRF &&
-		entry->dst.reg == inst->dst.reg &&
-		entry->dst.reg_offset >= start_offset &&
-		entry->dst.reg_offset < end_offset) {
-	       entry->remove();
-	       continue;
-	    }
-	    if (entry->src.file == GRF &&
-		entry->src.reg == inst->dst.reg &&
-		entry->src.reg_offset >= start_offset &&
-		entry->src.reg_offset < end_offset) {
+	    if (inst->overwrites_reg(entry->dst) ||
+                inst->overwrites_reg(entry->src)) {
 	       entry->remove();
 	    }
 	 }
       }
 
       /* If this instruction is a raw copy, add it to the ACP. */
diff --git a/src/mesa/drivers/dri/i965/brw_fs_cse.cpp b/src/mesa/drivers/dri/i965/brw_fs_cse.cpp
index fd28e14fd0e..7bf6698f91e 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_cse.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_cse.cpp
@@ -147,23 +147,17 @@ fs_visitor::opt_cse_local(fs_bblock *block, exec_list *aeb)
 	    /* Continue iteration with copy->next */
 	    inst = copy;
 	 }
       }
 
       /* Kill all AEB entries that use the destination. */
-      int start_offset = inst->dst.reg_offset;
-      int end_offset = start_offset + inst->regs_written();
-
       foreach_list_safe(entry_node, aeb) {
 	 aeb_entry *entry = (aeb_entry *)entry_node;
 
 	 for (int i = 0; i < 3; i++) {
-	    if (entry->generator->src[i].file == inst->dst.file &&
-		entry->generator->src[i].reg == inst->dst.reg &&
-		entry->generator->src[i].reg_offset >= start_offset &&
-		entry->generator->src[i].reg_offset < end_offset) {
+            if (inst->overwrites_reg(entry->generator->src[i])) {
 	       entry->remove();
 	       ralloc_free(entry);
 	       break;
 	    }
 	 }
       }