panfrost/midgard: Fix nested/chained if-else

An if-else statement is compiled to a conditional branch (from the start
to the second block) and an unconditional branch (from the end of the
first block to the end of the else). We previously incorrectly computed
the block index of the unconditional branch to be exactly one after that
of the conditional branch, valid for a single if-else statement but
nothing fancier. This patch correctly computes the unconditional branch
target, fixing more complex if-else chains.

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

diff --git a/src/gallium/drivers/panfrost/midgard/midgard_compile.c b/src/gallium/drivers/panfrost/midgard/midgard_compile.c
index de9420685f5e1183e0cbb4e0e223ce3752dd271b..bcd6bf151c1a116123da8a7bf0a74342f91f9a31 100644 (file)
--- a/src/gallium/drivers/panfrost/midgard/midgard_compile.c
+++ b/src/gallium/drivers/panfrost/midgard/midgard_compile.c
@@ -3182,20 +3182,20 @@ emit_if(struct compiler_context *ctx, nir_if *nif)
         int else_idx = ctx->block_count;
         int count_in = ctx->instruction_count;
         midgard_block *else_block = emit_cf_list(ctx, &nif->else_list);
+        int after_else_idx = ctx->block_count;
 
         /* Now that we have the subblocks emitted, fix up the branches */
 
         assert(then_block);
         assert(else_block);
 
-
         if (ctx->instruction_count == count_in) {
                 /* The else block is empty, so don't emit an exit jump */
                 mir_remove_instruction(then_exit);
-                then_branch->branch.target_block = else_idx + 1;
+                then_branch->branch.target_block = after_else_idx;
         } else {
                 then_branch->branch.target_block = else_idx;
-                then_exit->branch.target_block = else_idx + 1;
+                then_exit->branch.target_block = after_else_idx;
         }
 }