Mesa (main): broadcom/compiler: apply constant folding on early GS lowering

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Module: Mesa
Branch: main
Commit: 457dbb81f5c3bc86d4968c6f099154abd39c829e
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=457dbb81f5c3bc86d4968c6f099154abd39c829e

Author: Juan A. Suarez Romero <jasuarez at igalia.com>
Date:   Fri Nov 19 19:09:56 2021 +0100

broadcom/compiler: apply constant folding on early GS lowering

This solves a case where a NIR geometry shader was storing the output in
a non-constant:

  vec4 32 ssa_1 = load_const (0xc0800000 /* -4.000000 */, 0xc1100000 /* -9.000000 */, 0x40400000 /* 3.000000 */, 0x40e00000 /* 7.000000 */)
  vec1 32 ssa_7 = load_const (0x00000000 /* 0.000000 */)
  vec1 32 ssa_8 = load_const (0x00000001 /* 0.000000 */)
  vec1 32 ssa_9 = iadd ssa_7, ssa_8
  vec1 32 ssa_19 = mov ssa_1.x
  intrinsic store_output (ssa_19, ssa_9) (1, 1, 0, 160, 288) /* base=1 */ /* wrmask=x */ /* component=0 */ /* src_type=float32 */ /* location=32 slots=2 gs_streams(x=0 y=0 z=0 w=0) */

When lowering the VPM output we check if the destination (ssa_9 in this
case) is a constant to add to the VPM offset. We run a constant folding
optimization in an earlier VS lowering, and we should do the same for
GS.

This fixes multiple dEQP-VK.pipeline.interface_matching.* failures.

Signed-off-by: Juan A. Suarez Romero <jasuarez at igalia.com>
Reviewed-by: Iago Toral Quiroga <itoral at igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13884>

---

 src/broadcom/compiler/vir.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/broadcom/compiler/vir.c b/src/broadcom/compiler/vir.c
index bf75a4da170..127709d1de3 100644
--- a/src/broadcom/compiler/vir.c
+++ b/src/broadcom/compiler/vir.c
@@ -937,8 +937,11 @@ v3d_nir_lower_gs_early(struct v3d_compile *c)
         NIR_PASS_V(c->s, nir_lower_io, nir_var_shader_in | nir_var_shader_out,
                    type_size_vec4,
                    (nir_lower_io_options)0);
-        /* clean up nir_lower_io's deref_var remains */
+        /* clean up nir_lower_io's deref_var remains and do a constant folding pass
+         * on the code it generated.
+         */
         NIR_PASS_V(c->s, nir_opt_dce);
+        NIR_PASS_V(c->s, nir_opt_constant_folding);
 }
 
 static void