panfrost: Rectify doubleplusungood extended branch

Midgard features "compact branches" and "extended branches", i.e.
corresponds to short jumps and far jumps. The form of the extended
branch was previously incorrect in the ISA headers; this patch corrects
it and updates the disassembler (simultaneous to preserve
bisectability).

Additionally, we fix some a corner case in the disassembly of extended
branches, and we now prefix extended branches with "brx", to visually
differentiate from compact branches prefixed with "br".

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>

diff --git a/src/gallium/drivers/panfrost/midgard/disassemble.c b/src/gallium/drivers/panfrost/midgard/disassemble.c
index afde3fdbbcd405c54a64af0fd10f9cee655fbe26..7e5c5803f75da61fbb5294bb5d8d1282d19d5ffc 100644 (file)
--- a/src/gallium/drivers/panfrost/midgard/disassemble.c
+++ b/src/gallium/drivers/panfrost/midgard/disassemble.c
@@ -373,6 +373,10 @@ static void
 print_branch_op(int op)
 {
         switch (op) {
+        case midgard_jmp_writeout_op_branch_uncond:
+                printf("uncond.");
+                break;
+
         case midgard_jmp_writeout_op_branch_cond:
                 printf("cond.");
                 break;
@@ -412,6 +416,7 @@ print_branch_cond(int cond)
                 break;
 
         default:
+                printf("unk%X", cond);
                 break;
         }
 }
@@ -470,17 +475,13 @@ print_extended_branch_writeout_field(uint8_t *words)
         midgard_branch_extended br;
         memcpy((char *) &br, (char *) words, sizeof(br));
 
-        printf("br.");
+        printf("brx.");
 
         print_branch_op(br.op);
         print_branch_cond(br.cond);
 
-        /* XXX: This can't be right */
         if (br.unknown)
-                printf(".unknown%d\n", br.unknown);
-
-        if (br.zero)
-                printf(".zero%d\n", br.zero);
+                printf(".unknown%d", br.unknown);
 
         printf(" ");
 

diff --git a/src/gallium/drivers/panfrost/midgard/midgard.h b/src/gallium/drivers/panfrost/midgard/midgard.h
index b6cd38a5cd07e08ca308c2aec890adb675d591f4..04e195a635dc88ca9097df41632ef3fa05a841f1 100644 (file)
--- a/src/gallium/drivers/panfrost/midgard/midgard.h
+++ b/src/gallium/drivers/panfrost/midgard/midgard.h
@@ -231,8 +231,7 @@ __attribute__((__packed__))
         midgard_jmp_writeout_op op : 3; /* == branch_cond */
         unsigned dest_tag : 4; /* tag of branch destination */
         unsigned unknown : 2;
-        signed offset : 7;
-        unsigned zero : 16;
+        signed offset : 23;
         unsigned cond : 16;
 }
 midgard_branch_extended;