From: Eric Anholt <eric@anholt.net>
Date: Sun, 3 Apr 2011 04:11:32 +0000 (-1000)
Subject: i965/fs: Remove broken optimization for live intervals in loops.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=963431829055f63ec94d;p=mesa.git

i965/fs: Remove broken optimization for live intervals in loops.

The theory here was to detect a temporary variable used within a loop,
and avoid considering it live across the entire loop.  However, it was
overeager and failed when the first definition of the variable
appeared within the loop but was only conditionally defined.

Fixes glsl-fs-loop-redundant-condition.
---

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index cada1401821..99cd8f833a7 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -2812,8 +2812,7 @@ fs_visitor::calculate_live_intervals()
 	    if (inst->src[i].file == GRF && inst->src[i].reg != 0) {
 	       int reg = inst->src[i].reg;
 
-	       if (!loop_depth || (this->virtual_grf_sizes[reg] == 1 &&
-				   def[reg] >= bb_header_ip)) {
+	       if (!loop_depth) {
 		  use[reg] = ip;
 	       } else {
 		  def[reg] = MIN2(loop_start, def[reg]);
@@ -2829,8 +2828,7 @@ fs_visitor::calculate_live_intervals()
 	 if (inst->dst.file == GRF && inst->dst.reg != 0) {
 	    int reg = inst->dst.reg;
 
-	    if (!loop_depth || (this->virtual_grf_sizes[reg] == 1 &&
-				!inst->predicated)) {
+	    if (!loop_depth) {
 	       def[reg] = MIN2(def[reg], ip);
 	    } else {
 	       def[reg] = MIN2(def[reg], loop_start);