Mesa (main): r300: Cache the var list in the peephole_mul_omod() loop.

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Module: Mesa
Branch: main
Commit: 915af8de8b15886c9fe12ff4bed4fa1fbb904464
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=915af8de8b15886c9fe12ff4bed4fa1fbb904464

Author: Emma Anholt <emma at anholt.net>
Date:   Tue Dec  7 11:09:06 2021 -0800

r300: Cache the var list in the peephole_mul_omod() loop.

If we're not making progress (which the function was already giving us!),
then there's no need to recompute the list.  Reduces
pixmark-piano/7.shader_test compile time from 50 seconds to 10.

Reviewed-by: Marek Olšák <marek.olsak at amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14117>

---

 src/gallium/drivers/r300/compiler/radeon_optimize.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/gallium/drivers/r300/compiler/radeon_optimize.c b/src/gallium/drivers/r300/compiler/radeon_optimize.c
index c106d8d74e6..5c825a0a62a 100644
--- a/src/gallium/drivers/r300/compiler/radeon_optimize.c
+++ b/src/gallium/drivers/r300/compiler/radeon_optimize.c
@@ -881,7 +881,6 @@ static int peephole(struct radeon_compiler * c, struct rc_instruction * inst)
 void rc_optimize(struct radeon_compiler * c, void *user)
 {
 	struct rc_instruction * inst = c->Program.Instructions.Next;
-	struct rc_list * var_list;
 	while(inst != &c->Program.Instructions) {
 		struct rc_instruction * cur = inst;
 		inst = inst->Next;
@@ -902,12 +901,15 @@ void rc_optimize(struct radeon_compiler * c, void *user)
 	}
 
 	inst = c->Program.Instructions.Next;
+	struct rc_list * var_list = NULL;
 	while(inst != &c->Program.Instructions) {
 		struct rc_instruction * cur = inst;
 		inst = inst->Next;
 		if (cur->U.I.Opcode == RC_OPCODE_MUL) {
-			var_list = rc_get_variables(c);
-			peephole_mul_omod(c, cur, var_list);
+			if (!var_list)
+				var_list = rc_get_variables(c);
+			if (peephole_mul_omod(c, cur, var_list))
+				var_list = NULL;
 		}
 	}
 }