Add performance test for ghci, -fno-code and reloading (#20509)

This test triggers the bad code path identified by #20509 where an entry
into the EPS caused by importing Control.Applicative will retain a stale
HomePackageTable.

3 files changed, 48 insertions, 0 deletions

diff --git a/testsuite/tests/perf/compiler/MultiLayerModulesNoCode.script b/testsuite/tests/perf/compiler/MultiLayerModulesNoCode.script
new file mode 100644
index 0000000000..dba747c630
--- /dev/null
+++ b/testsuite/tests/perf/compiler/MultiLayerModulesNoCode.script
@@ -0,0 +1,3 @@
+:set -fno-code
+:l MultiLayerModules.hs
+:l MultiLayerModules.hs
diff --git a/testsuite/tests/perf/compiler/all.T b/testsuite/tests/perf/compiler/all.T
index b61ba25478..9f726cc755 100644
--- a/testsuite/tests/perf/compiler/all.T
+++ b/testsuite/tests/perf/compiler/all.T
@@ -306,6 +306,19 @@ test('MultiLayerModulesDefsGhci',
      ghci_script,
      ['MultiLayerModulesDefsGhci.script'])
 
+test('MultiLayerModulesNoCode',
+     [ collect_compiler_residency(15),
+       pre_cmd('./genMultiLayerModulesNoCode'),
+       extra_files(['genMultiLayerModulesNoCode']),
+       compile_timeout_multiplier(5)
+       # this is _a lot_
+       # but this test has been failing every now and then,
+       # especially on i386. Let's just give it some room
+       # to complete successfully reliably everywhere.
+     ],
+     ghci_script,
+     ['MultiLayerModulesNoCode.script'])
+
 test('ManyConstructors',
      [ collect_compiler_stats('bytes allocated',2),
        pre_cmd('./genManyConstructors'),
diff --git a/testsuite/tests/perf/compiler/genMultiLayerModulesNoCode b/testsuite/tests/perf/compiler/genMultiLayerModulesNoCode
new file mode 100755
index 0000000000..0cca953c30
--- /dev/null
+++ b/testsuite/tests/perf/compiler/genMultiLayerModulesNoCode
@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+# Generate $DEPTH layers of modules with $WIDTH modules on each layer
+# Every module on layer N imports all the modules on layer N-1
+# Each module has $DEFS definitions in
+# MultiLayerModules.hs imports all the modules from the last layer
+DEPTH=3
+WIDTH=3
+DEFS=1000
+for i in $(seq -w 1 $WIDTH); do
+  echo "module DummyLevel0M$i where" > DummyLevel0M$i.hs;
+  for k in $(seq -w 1 $DEFS); do
+     echo "a_0_${i}_${k} = ${i} + ${k}" >> DummyLevel${l}M$i.hs;
+  done
+done
+for l in $(seq 1 $DEPTH); do
+  for i in $(seq -w 1 $WIDTH); do
+    echo "module DummyLevel${l}M$i where" > DummyLevel${l}M$i.hs;
+    for j in $(seq -w 1 $WIDTH); do
+      echo "import DummyLevel$((l-1))M$j" >> DummyLevel${l}M$i.hs;
+    done
+    for k in $(seq -w 1 $DEFS); do
+      echo "a_${l}_${i}_${j}_${k} = ${l} + ${i} + ${j} + ${k}" >> DummyLevel${l}M$i.hs;
+    done
+  done
+done
+echo "module MultiLayerModules where" > MultiLayerModules.hs
+for j in $(seq -w 1 $WIDTH); do
+  echo "import DummyLevel${DEPTH}M$j" >> MultiLayerModules.hs;
+done
+# What this import is doesn't matter, as long as it's not from the home package
+# and not already imported implicitly.
+echo "import Control.Applicative" >> MultiLayerModules.hs;