test(compiler): add seeded C++ differential tests across seven groups

Generate 10000 random records per group plus boundary inputs using a
portable SHA-256 stream. Compare native and runner output independently.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

5 files changed, 54 insertions, 0 deletions

diff --git a/tests/ii/arithmetic/case.json b/tests/ii/arithmetic/case.json
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/tests/ii/arithmetic/case.json
@@ -0,0 +1 @@
+{}
diff --git a/tests/ii/arithmetic/generate.pl b/tests/ii/arithmetic/generate.pl
new file mode 100644
index 0000000..24236a8
--- /dev/null
+++ b/tests/ii/arithmetic/generate.pl
@@ -0,0 +1,23 @@
+use strict;
+use warnings;
+use FindBin;
+use lib "$FindBin::Bin/..";
+use Random;
+my ($seed, $count) = @ARGV;
+my $rng = Random->new($seed, "arithmetic");
+my @edges = (
+    '9223372036854775807 1',
+    '-9223372036854775808 1',
+    '-9223372036854775808 2',
+    '0 -1',
+    '7 -3',
+    '-7 3',
+    '-7 -3',
+    '1 1',
+);
+$rng->emit($count, \@edges, sub {
+my $a = $rng->integer(-1000000, 1000000);
+my $b = $rng->integer(-1000000, 1000000);
+$b = 1 if $b == 0;
+return "$a $b";
+});
diff --git a/tests/ii/arithmetic/notes.md b/tests/ii/arithmetic/notes.md
new file mode 100644
index 0000000..947a3fa
--- /dev/null
+++ b/tests/ii/arithmetic/notes.md
@@ -0,0 +1,5 @@
+# arithmetic
+
+CIE pp. 15-16, project i64 and truncation-towards-zero DIV/MOD. Full-width extremes are used only in safe division/remainder and comparisons; addition, subtraction and multiplication use A MOD 1000001. B is nonzero, and INT64_MIN / -1 is never generated.
+
+Each record produces exactly one output line. Random records are preceded by fixed boundary records; every arithmetic intermediate is bounded.
diff --git a/tests/ii/arithmetic/program.cps b/tests/ii/arithmetic/program.cps
new file mode 100644
index 0000000..7c4bf52
--- /dev/null
+++ b/tests/ii/arithmetic/program.cps
@@ -0,0 +1,12 @@
+DECLARE Count : INTEGER
+DECLARE Index : INTEGER
+DECLARE A : INTEGER
+DECLARE B : INTEGER
+DECLARE Small : INTEGER
+INPUT Count
+FOR Index <- 1 TO Count
+    INPUT A
+    INPUT B
+    Small <- A MOD 1000001
+    OUTPUT A < B, ":", A DIV B, ":", A MOD B, ":", Small + B, ":", Small - B, ":", Small * B
+NEXT Index
diff --git a/tests/ii/arithmetic/reference.cc b/tests/ii/arithmetic/reference.cc
new file mode 100644
index 0000000..6d3d98f
--- /dev/null
+++ b/tests/ii/arithmetic/reference.cc
@@ -0,0 +1,13 @@
+#include <cstdint>
+#include <iostream>
+int main() {
+    int count;
+    if (!(std::cin >> count)) return 1;
+    for (int i = 0; i < count; ++i) {
+        std::int64_t a, b;
+        if (!(std::cin >> a >> b) || b == 0) return 1;
+        auto small = a % 1000001;
+        std::cout << (a < b ? "TRUE" : "FALSE") << ':' << a / b << ':' << a % b
+                  << ':' << small + b << ':' << small - b << ':' << small * b << '\n';
+    }
+}