Mesa (main): agx: Handle loop { if { loop { .. } } }

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Module: Mesa
Branch: main
Commit: 76981e5615fae277dd2f2ed0b6f2a455bd7d5fc1
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=76981e5615fae277dd2f2ed0b6f2a455bd7d5fc1

Author: Alyssa Rosenzweig <alyssa at rosenzweig.io>
Date:   Sat Jun 11 19:57:38 2022 -0400

agx: Handle loop { if { loop { .. } } }

We need to push loop nesting to handle this correctly -- at the end of
the innermost loop, the correct nesting is 1 (from the if), not 0.

Fixes assertion failure in

  dEQP-GLES2.functional.shaders.struct.local.dynamic_loop_nested_struct_array_fragment,UnexpectedPass
  dEQP-GLES2.functional.shaders.struct.local.dynamic_loop_nested_struct_array_vertex,UnexpectedPass
  dEQP-GLES2.functional.shaders.struct.uniform.dynamic_loop_nested_struct_array_fragment,UnexpectedPass
  dEQP-GLES2.functional.shaders.struct.uniform.dynamic_loop_nested_struct_array_vertex,UnexpectedPass

Signed-off-by: Alyssa Rosenzweig <alyssa at rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17128>

---

 src/asahi/compiler/agx_compile.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/asahi/compiler/agx_compile.c b/src/asahi/compiler/agx_compile.c
index e787ddfc1a4..321c2d437ca 100644
--- a/src/asahi/compiler/agx_compile.c
+++ b/src/asahi/compiler/agx_compile.c
@@ -1206,7 +1206,8 @@ emit_if(agx_context *ctx, nir_if *nif)
 static void
 emit_loop(agx_context *ctx, nir_loop *nloop)
 {
-   /* We only track nesting within the innermost loop, so reset */
+   /* We only track nesting within the innermost loop, so push and reset */
+   unsigned pushed_nesting = ctx->loop_nesting;
    ctx->loop_nesting = 0;
 
    agx_block *popped_break = ctx->break_block;
@@ -1246,6 +1247,9 @@ emit_loop(agx_context *ctx, nir_loop *nloop)
 
    /* All nested control flow must have finished */
    assert(ctx->loop_nesting == 0);
+
+   /* Restore loop nesting (we might be inside an if inside an outer loop) */
+   ctx->loop_nesting = pushed_nesting;
 }
 
 /* Before the first control flow structure, the nesting counter (r0l) needs to