From ea49ede5d221267cfd494fbfa13f41b87d81c43e Mon Sep 17 00:00:00 2001
From: thorstenhater <24411438+thorstenhater@users.noreply.github.com>
Date: Wed, 20 May 2020 14:31:05 +0200
Subject: [PATCH] Modcc/optimise divide by const (#1043)
Add a simple re-write to eliminate division by a known constant.
---
modcc/symdiff.cpp | 3 +++
test/unit-modcc/test_printers.cpp | 2 +-
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/modcc/symdiff.cpp b/modcc/symdiff.cpp
index 27c2ff2b..03b3d4f2 100644
--- a/modcc/symdiff.cpp
+++ b/modcc/symdiff.cpp
@@ -430,6 +430,9 @@ public:
else if (expr_value(rhs)==1) {
result_ = e->lhs()->clone();
}
+ else if (is_number(rhs)) {
+ result_ = make_expression<MulBinaryExpression>(loc, std::move(lhs), make_expression<NumberExpression>(loc, 1.0/expr_value(rhs)));
+ }
else {
result_ = make_expression<DivBinaryExpression>(loc, std::move(lhs), std::move(rhs));
}
diff --git a/test/unit-modcc/test_printers.cpp b/test/unit-modcc/test_printers.cpp
index d99d6c8b..fa8bd3ab 100644
--- a/test/unit-modcc/test_printers.cpp
+++ b/test/unit-modcc/test_printers.cpp
@@ -200,7 +200,7 @@ TEST(CPrinter, proc_body_const) {
TEST(CPrinter, proc_body_inlined) {
const char* expected =
- "r_9_=s2[i_]/3;\n"
+ "r_9_=s2[i_]*0.33333333333333331;\n"
"r_8_=s1[i_]+2;\n"
"if(s1[i_]==3){\n"
" r_7_=2*r_8_;\n"
--
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