Makefile.rules: Use a shared clang module cache directory.

Just to be safe, up until now each test used its own Clang module
cache directory. Since the compiler within one testsuite doesn't
change it is just as safe to share a clang module directory inside the
LLDB test build directory. This saves us from compiling tens of
gigabytes of redundant Darwin and Foundation .pcm files and also
speeds up running the test suite quite significantly.

rdar://problem/36002081

Differential Revision: https://reviews.llvm.org/D54601

llvm-svn: 347056

2 files changed, 19 insertions, 2 deletions

diff --git a/lldb/lit/lit.cfg.py b/lldb/lit/lit.cfg.py
index 9b78ba35c16..86cc9022101 100644
--- a/lldb/lit/lit.cfg.py
+++ b/lldb/lit/lit.cfg.py
@@ -4,9 +4,9 @@ import os
 import sys
 import re
 import platform
+import shutil
 import subprocess
 
-
 import lit.util
 import lit.formats
 from lit.llvm import llvm_config
@@ -124,3 +124,12 @@ llvm_config.feature_config(
      ('--build-mode', {'DEBUG': 'debug'}),
      ('--targets-built', calculate_arch_features)
      ])
+
+# Clean the module caches in the test build directory.  This is
+# necessary in an incremental build whenever clang changes underneath,
+# so doing it once per lit.py invocation is close enough.
+for i in ['module-cache-clang']:
+    cachedir = os.path.join(config.llvm_obj_root, 'lldb-test-build.noindex', i)
+    if os.path.isdir(cachedir):
+        print("Deleting module cache at %s."%cachedir)
+        shutil.rmtree(cachedir)
diff --git a/lldb/packages/Python/lldbsuite/test/make/Makefile.rules b/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
index 89906516685..dfe573c89d7 100644
--- a/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
+++ b/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
@@ -33,7 +33,6 @@ BUILDDIR := $(shell pwd)
 THIS_FILE_DIR := $(shell dirname $(lastword $(MAKEFILE_LIST)))/
 LLDB_BASE_DIR := $(THIS_FILE_DIR)../../../../../
 
-
 #----------------------------------------------------------------------
 # If OS is not defined, use 'uname -s' to determine the OS name.
 #
@@ -253,7 +252,16 @@ ifeq "$(MAKE_DWO)" "YES"
 	CFLAGS += -gsplit-dwarf
 endif
 
+# Use a shared module cache when building in the default test build directory.
+ifeq "$(findstring lldb-test-build.noindex, $(BUILDDIR))" ""
 CLANG_MODULE_CACHE_DIR := $(BUILDDIR)/module-cache
+else
+CLANG_MODULE_CACHE_DIR := $(shell echo "$(BUILDDIR)" | sed 's/lldb-test-build.noindex.*/lldb-test-build.noindex\/module-cache-clang/')
+endif
+
+ifeq "$(CLANG_MODULE_CACHE_DIR)" ""
+$(error failed to set the shared clang module cache dir)
+endif
 
 MANDATORY_MODULE_BUILD_CFLAGS := -fmodules -gmodules -fmodules-cache-path=$(CLANG_MODULE_CACHE_DIR)