From e130557d9fce5ae426c040a72786012bfce407a1 Mon Sep 17 00:00:00 2001
From: florian <florian@freepascal.org>
Date: Wed, 17 Apr 2024 23:29:13 +0200
Subject: [PATCH]   * optimize x < length(arr) and x >= length(arr) as proposed
 in #40292

---
 compiler/nadd.pas       | 25 +++++++++++++++++++++++++
 tests/webtbs/tw40292.pp | 12 ++++++++++++
 2 files changed, 37 insertions(+)
 create mode 100644 tests/webtbs/tw40292.pp

diff --git a/compiler/nadd.pas b/compiler/nadd.pas
index 6bec18a2a8..f321893b97 100644
--- a/compiler/nadd.pas
+++ b/compiler/nadd.pas
@@ -1739,6 +1739,31 @@ implementation
                    ;
               end;
 
+            {
+              compile x < length(arr) as x <= high(arr)
+              compile x >= length(arr) as x > high(arr)
+
+              tested by tests/webtbs/tw40292.pp
+            }
+            if (nodetype in [ltn,gten]) and
+              (right.nodetype=inlinen) and (tinlinenode(right).inlinenumber=in_length_x) and
+              ((is_dynamic_array(tinlinenode(right).left.resultdef)) or
+               (is_open_array(tinlinenode(right).left.resultdef))
+              ) then
+              begin
+                case nodetype of
+                  ltn:
+                    result:=caddnode.create(lten,left,cinlinenode.create(in_high_x,false,tinlinenode(right).left));
+                  gten:
+                    result:=caddnode.create(gtn,left,cinlinenode.create(in_high_x,false,tinlinenode(right).left));
+                  else
+                    Internalerror(2024041701);
+                end;
+                left:=nil;
+                tinlinenode(right).left:=nil;
+                exit;
+              end;
+
             { using sqr(x) for reals instead of x*x might reduces register pressure and/or
               memory accesses while sqr(<real>) has no drawback }
             if
diff --git a/tests/webtbs/tw40292.pp b/tests/webtbs/tw40292.pp
new file mode 100644
index 0000000000..3708c9c6c5
--- /dev/null
+++ b/tests/webtbs/tw40292.pp
@@ -0,0 +1,12 @@
+var
+  arr: array of longint;
+  x: longint;
+begin
+  x:=12+random(0);
+  setlength(arr,13+random(0));
+  if (x < length(arr)) <> (x <= high(arr)) then
+    halt(1);
+  x:=13+random(0);
+  if (x >= length(arr)) <> (x > high(arr)) then
+    halt(2);
+end.