Mesa (master): i965/vec4: Ignore swizzle of VGRF for use by var_range_end()
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Wed May 20 20:32:12 UTC 2020
Module: Mesa
Branch: master
Commit: d1b746284985a34e61c315ba586c789c607ac3ba
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=d1b746284985a34e61c315ba586c789c607ac3ba
Author: Andrii Simiklit <asimiklit.work at gmail.com>
Date: Thu May 7 12:46:28 2020 +0300
i965/vec4: Ignore swizzle of VGRF for use by var_range_end()
Issue description from Matt's commit e7c376ad:
"var_range_end(v, n) loops over the n components of variable number v and
finds the maximum value, giving the last use of any component of v.
Therefore it expects v to correspond to the variable associated with the
.x channel of the VGRF.
var_from_reg() however returns the variable for the first channel of the
VGRF, post-swizzle.
So, if the last register had a swizzle with y, z, or w in the swizzle
component, we would read out of bounds. For any other register, we would
read liveness information from the next register.
The fix is to convert the src_reg to a dst_reg in order to call the
dst_reg version of var_from_reg() that doesn't consider the swizzle."
Closes: #3003
Fixes: 48dfb30f ('intel/compiler: Move all live interval analysis results into vec4_live_variables')
Reviewed-by: Matt Turner <mattst88 at gmail.com>
Signed-off-by: Andrii Simiklit <asimiklit.work at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4941>
---
src/intel/compiler/brw_vec4_cse.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/intel/compiler/brw_vec4_cse.cpp b/src/intel/compiler/brw_vec4_cse.cpp
index 585676a9042..accc037af8d 100644
--- a/src/intel/compiler/brw_vec4_cse.cpp
+++ b/src/intel/compiler/brw_vec4_cse.cpp
@@ -288,7 +288,7 @@ vec4_visitor::opt_cse_local(bblock_t *block, const vec4_live_variables &live)
* more -- a sure sign they'll fail operands_match().
*/
if (src->file == VGRF) {
- if (live.var_range_end(var_from_reg(alloc, *src), 8) < ip) {
+ if (live.var_range_end(var_from_reg(alloc, dst_reg(*src)), 8) < ip) {
entry->remove();
ralloc_free(entry);
break;
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