[SYCL][E2E] Substitute paths to lit tool binaries (#9041)

This change makes LIT explicitly substitute uses of tool binaries in
tests with their full paths. This makes test RUN lines easier to
reproduce, as it negates the effect of lit's internal environment (e.g.,
PATH) on which tools are run.

The list of tools affected are: sycl-ls llvm-spirv, llvm-link, FileCheck
and not (when used after a pipe).

This also changes the behaviour of how LIT finds sycl-ls, llvm-spirv,
and llvm-link. Whereas before these tools were found only on the PATH,
now they will be preferably sourced first from the in-tree tools
directory.

Author: frasercrmck

sycl/test-e2e/README.md

@@ -181,6 +181,8 @@ unavailable.
  * **gpu-intel-dg2** - Intel GPU DG2 availability;
  * **gpu-intel-pvc** - Intel GPU PVC availability;
  * **dump_ir**: - compiler can / cannot dump IR;
+ * **llvm-spirv** - llvm-spirv tool availability;
+ * **llvm-link** - llvm-link tool availability;
 
 ## llvm-lit parameters
 

sycl/test-e2e/lit.cfg.py

@@ -11,6 +11,7 @@
 import lit.util
 
 from lit.llvm import llvm_config
+from lit.llvm.subst import ToolSubst, FindTool
 
 # Configuration file for the 'lit' test runner.
 
@@ -34,6 +35,9 @@
 # test_exec_root: The root path where tests should be run.
 config.test_exec_root = config.sycl_obj_root
 
+# allow expanding substitutions that are based on other substitutions
+config.recursiveExpansionLimit = 10
+
 # Cleanup environment variables which may affect tests
 possibly_dangerous_env_vars = ['COMPILER_PATH', 'RC_DEBUG_OPTIONS',
                                'CINDEXTEST_PREAMBLE_FILE', 'LIBRARY_PATH',
@@ -390,7 +394,6 @@
 
 if config.run_launcher:
     config.substitutions.append(('%e2e_tests_root', config.test_source_root))
-    config.recursiveExpansionLimit = 10
 
 if config.sycl_be == 'ext_oneapi_cuda' or (config.sycl_be == 'ext_oneapi_hip' and config.hip_platform == 'NVIDIA'):
     config.substitutions.append( ('%sycl_triple',  "nvptx64-nvidia-cuda" ) )
@@ -399,9 +402,6 @@
 else:
     config.substitutions.append( ('%sycl_triple',  "spir64" ) )
 
-if find_executable('sycl-ls'):
-    config.available_features.add('sycl-ls')
-
 # TODO properly set XPTIFW include and runtime dirs
 xptifw_lib_dir = os.path.join(config.dpcpp_root_dir, 'lib')
 xptifw_dispatcher = ""
@@ -418,17 +418,32 @@
     else:
         config.substitutions.append(('%xptifw_lib', " -L{} -lxptifw -I{} ".format(xptifw_lib_dir, xptifw_includes)))
 
-
-llvm_tools = ["llvm-spirv", "llvm-link"]
-for llvm_tool in llvm_tools:
-  llvm_tool_path = find_executable(llvm_tool)
-  if llvm_tool_path:
-    lit_config.note("Found " + llvm_tool)
-    config.available_features.add(llvm_tool)
-    config.substitutions.append( ('%' + llvm_tool.replace('-', '_'),
-                                  os.path.realpath(llvm_tool_path)) )
-  else:
-    lit_config.warning("Can't find " + llvm_tool)
+# Tools for which we add a corresponding feature when available.
+feature_tools = [
+  ToolSubst('llvm-spirv', unresolved='ignore'),
+  ToolSubst('llvm-link', unresolved='ignore'),
+]
+
+tools = [
+  ToolSubst('FileCheck', unresolved='ignore'),
+  # not is only substituted in certain circumstances; this is lit's default
+  # behaviour.
+  ToolSubst(r'\| \bnot\b', command=FindTool('not'),
+    verbatim=True, unresolved='ignore'),
+  ToolSubst('sycl-ls', unresolved='ignore'),
+] + feature_tools
+
+# Try and find each of these tools in the llvm tools directory or the PATH, in
+# that order. If found, they will be added as substitutions with the full path
+# to the tool. This allows us to support both in-tree builds and standalone
+# builds, where the tools may be externally defined.
+llvm_config.add_tool_substitutions(tools, [config.llvm_tools_dir,
+                                           os.environ.get('PATH', '')])
+for tool in feature_tools:
+    if tool.was_resolved:
+        config.available_features.add(tool.key)
+    else:
+        lit_config.warning("Can't find " + tool.key)
 
 if find_executable('cmc'):
     config.available_features.add('cm-compiler')