From cd4e0e8ca447158dcc7c7f95cac2adcc43f99094 Mon Sep 17 00:00:00 2001
From: Max Graey <maxgraey@gmail.com>
Date: Tue, 12 Oct 2021 20:20:30 +0300
Subject: [Costs] More precise costs for int div & rem (#4229)

Div/rem by a constant can be optimized by VMs, so it is usually
closer to the speed of a mul.

Div on 64-bit (either with or without a constant) can be slower
than 32-bit, so bump that up by one as well.
---
 src/ir/cost.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'src')

diff --git a/src/ir/cost.h b/src/ir/cost.h
index 7c18a8200..0463d3310 100644
--- a/src/ir/cost.h
+++ b/src/ir/cost.h
@@ -253,7 +253,7 @@ struct CostAnalyzer : public OverriddenVisitor<CostAnalyzer, CostType> {
       case DivUInt32:
       case RemSInt32:
       case RemUInt32:
-        ret = 3;
+        ret = curr->right->is<Const>() ? 2 : 3;
         break;
       case AndInt32:
       case OrInt32:
@@ -274,7 +274,7 @@ struct CostAnalyzer : public OverriddenVisitor<CostAnalyzer, CostType> {
       case DivUInt64:
       case RemSInt64:
       case RemUInt64:
-        ret = 3;
+        ret = curr->right->is<Const>() ? 3 : 4;
         break;
       case AndInt64:
       case OrInt64:
-- 
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