Mesa (master): nir/copy_prop: remove unused copies

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Module: Mesa
Branch: master
Commit: 41125bff4ff2e79895975f76601a6c7a18029a3d
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=41125bff4ff2e79895975f76601a6c7a18029a3d

Author: Rhys Perry <pendingchaos02 at gmail.com>
Date:   Fri Jan 29 14:32:50 2021 +0000

nir/copy_prop: remove unused copies

These were hurting performance of other passes.

Compile-time (overall):
Difference at 95.0% confidence
	-5496.3 +/- 219.752
	-4.11912% +/- 0.160285%
	(Student's t, pooled s = 259.538)

Signed-off-by: Rhys Perry <pendingchaos02 at gmail.com>
Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
Reviewed-by: Connor Abbott <cwabbott0 at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8784>

---

 src/compiler/nir/nir_opt_copy_propagate.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/compiler/nir/nir_opt_copy_propagate.c b/src/compiler/nir/nir_opt_copy_propagate.c
index be9bce3ef2e..52c8acec306 100644
--- a/src/compiler/nir/nir_opt_copy_propagate.c
+++ b/src/compiler/nir/nir_opt_copy_propagate.c
@@ -99,7 +99,8 @@ copy_prop_src(nir_src *src, nir_instr *parent_instr, nir_if *parent_if,
 {
    assert(src->is_ssa);
 
-   nir_instr *src_instr = src->ssa->parent_instr;
+   nir_ssa_def *original_ssa = src->ssa;
+   nir_instr *src_instr = original_ssa->parent_instr;
    nir_ssa_def *copy_def;
    if (src_instr->type == nir_instr_type_alu) {
       nir_alu_instr *alu_instr = nir_instr_as_alu(src_instr);
@@ -121,6 +122,9 @@ copy_prop_src(nir_src *src, nir_instr *parent_instr, nir_if *parent_if,
       nir_if_rewrite_condition(parent_if, nir_src_for_ssa(copy_def));
    }
 
+   if (nir_ssa_def_is_unused(original_ssa))
+      nir_instr_remove(src_instr);
+
    return true;
 }
 
@@ -130,7 +134,8 @@ copy_prop_alu_src(nir_alu_instr *parent_alu_instr, unsigned index)
    nir_alu_src *src = &parent_alu_instr->src[index];
    assert(src->src.is_ssa);
 
-   nir_instr *src_instr =  src->src.ssa->parent_instr;
+   nir_ssa_def *original_ssa = src->src.ssa;
+   nir_instr *src_instr = original_ssa->parent_instr;
    if (src_instr->type != nir_instr_type_alu)
       return false;
 
@@ -169,6 +174,9 @@ copy_prop_alu_src(nir_alu_instr *parent_alu_instr, unsigned index)
    nir_instr_rewrite_src(&parent_alu_instr->instr, &src->src,
                          nir_src_for_ssa(def));
 
+   if (nir_ssa_def_is_unused(original_ssa))
+      nir_instr_remove(src_instr);
+
    return true;
 }