i965/vec4: Reswizzle sources when necessary.

Despite the comment above the function claiming otherwise, the function
did not reswizzle sources, which would lead to bad code generation since
commit 04895f5c, which began claiming we could do such swizzling when we
could not.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82932
Reviewed-by: Kenneth Graunke <[email protected]>
(cherry picked from commit 1ee1d8ab468cafd25cfcc513319f3f046492947f)

2 files changed, 25 insertions, 11 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
index ee61202c358..4010ad643d2 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -933,9 +933,9 @@ vec4_visitor::opt_set_dependency_control()
 }
 
 bool
-vec4_instruction::can_reswizzle_dst(int dst_writemask,
-                                    int swizzle,
-                                    int swizzle_mask)
+vec4_instruction::can_reswizzle(int dst_writemask,
+                                int swizzle,
+                                int swizzle_mask)
 {
    /* If this instruction sets anything not referenced by swizzle, then we'd
     * totally break it when we reswizzle.
@@ -977,9 +977,10 @@ vec4_instruction::can_reswizzle_dst(int dst_writemask,
  * e.g. for swizzle=yywx, MUL a.xy b c -> MUL a.yy_x b.yy z.yy_x
  */
 void
-vec4_instruction::reswizzle_dst(int dst_writemask, int swizzle)
+vec4_instruction::reswizzle(int dst_writemask, int swizzle)
 {
    int new_writemask = 0;
+   int new_swizzle[4] = { 0 };
 
    switch (opcode) {
    default:
@@ -996,6 +997,19 @@ vec4_instruction::reswizzle_dst(int dst_writemask, int swizzle)
          }
          break;
       }
+
+      for (int i = 0; i < 3; i++) {
+         if (src[i].file == BAD_FILE || src[i].file == IMM)
+            continue;
+
+         for (int c = 0; c < 4; c++) {
+            new_swizzle[c] = BRW_GET_SWZ(src[i].swizzle, BRW_GET_SWZ(swizzle, c));
+         }
+
+         src[i].swizzle = BRW_SWIZZLE4(new_swizzle[0], new_swizzle[1],
+                                       new_swizzle[2], new_swizzle[3]);
+      }
+
       /* fallthrough */
    case BRW_OPCODE_DP4:
    case BRW_OPCODE_DP3:
@@ -1102,9 +1116,9 @@ vec4_visitor::opt_register_coalesce()
             }
 
             /* If we can't handle the swizzle, bail. */
-            if (!scan_inst->can_reswizzle_dst(inst->dst.writemask,
-                                              inst->src[0].swizzle,
-                                              swizzle_mask)) {
+            if (!scan_inst->can_reswizzle(inst->dst.writemask,
+                                          inst->src[0].swizzle,
+                                          swizzle_mask)) {
                break;
             }
 
@@ -1190,8 +1204,8 @@ vec4_visitor::opt_register_coalesce()
 	    if (scan_inst->dst.file == GRF &&
 		scan_inst->dst.reg == inst->src[0].reg &&
 		scan_inst->dst.reg_offset == inst->src[0].reg_offset) {
-               scan_inst->reswizzle_dst(inst->dst.writemask,
-                                        inst->src[0].swizzle);
+               scan_inst->reswizzle(inst->dst.writemask,
+                                    inst->src[0].swizzle);
 	       scan_inst->dst.file = inst->dst.file;
 	       scan_inst->dst.reg = inst->dst.reg;
 	       scan_inst->dst.reg_offset = inst->dst.reg_offset;
diff --git a/src/mesa/drivers/dri/i965/brw_vec4.h b/src/mesa/drivers/dri/i965/brw_vec4.h
index f0239cb998a..48ef2bb15da 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.h
+++ b/src/mesa/drivers/dri/i965/brw_vec4.h
@@ -220,8 +220,8 @@ public:
    bool header_present;
 
    bool is_send_from_grf();
-   bool can_reswizzle_dst(int dst_writemask, int swizzle, int swizzle_mask);
-   void reswizzle_dst(int dst_writemask, int swizzle);
+   bool can_reswizzle(int dst_writemask, int swizzle, int swizzle_mask);
+   void reswizzle(int dst_writemask, int swizzle);
    bool can_do_source_mods(struct brw_context *brw);
 
    bool reads_flag()