Make spirv-link usable in tests

This instructs CMake where to find spirv-link (i.e. within the
SPIRV-Tools) and makes it available to lit tests.

This patch also adds a test that is currently failing because global
variables without initializer aren't read properly after linking.

Author: mantognini

llvm-spirv/test/CMakeLists.txt

@@ -15,6 +15,11 @@ if(SPIRV_TOOLS_FOUND)
     set(SPIRV_TOOLS_SPIRV_AS_FOUND True)
   endif()
 
+  find_program(SPIRV_TOOLS_SPIRV_LINK NAMES spirv-link PATHS ${SPIRV_TOOLS_PREFIX}/bin)
+  if(SPIRV_TOOLS_SPIRV_LINK)
+    set(SPIRV_TOOLS_SPIRV_LINK_FOUND True)
+  endif()
+
   find_program(SPIRV_TOOLS_SPIRV_VAL NAMES spirv-val PATHS ${SPIRV_TOOLS_PREFIX}/bin)
   if(SPIRV_TOOLS_SPIRV_VAL)
     set(SPIRV_TOOLS_SPIRV_VAL_FOUND True)
@@ -28,6 +33,11 @@ if(NOT SPIRV_TOOLS_SPIRV_AS)
   set(SPIRV_TOOLS_SPIRV_AS_FOUND False)
 endif()
 
+if(NOT SPIRV_TOOLS_SPIRV_LINK)
+  message(WARNING "spirv-link not found! SPIR-V test involving the linker will not be run.")
+  set(SPIRV_TOOLS_SPIRV_LINK_FOUND False)
+endif()
+
 if(NOT SPIRV_TOOLS_SPIRV_VAL)
   message(WARNING "spirv-val not found! SPIR-V generated for test suite will not be validated.")
   set(SPIRV_TOOLS_SPIRV_VAL_FOUND False)

llvm-spirv/test/lit.cfg.py

@@ -60,6 +60,11 @@
     config.available_features.add('spirv-as')
     using_spirv_tools = True
 
+if config.spirv_tools_have_spirv_link:
+    llvm_config.add_tool_substitutions(['spirv-link'], [config.spirv_tools_bin_dir])
+    config.available_features.add('spirv-link')
+    using_spirv_tools = True
+
 if config.spirv_tools_have_spirv_val:
     llvm_config.add_tool_substitutions(['spirv-val'], [config.spirv_tools_bin_dir])
     using_spirv_tools = True

llvm-spirv/test/lit.site.cfg.py.in

@@ -16,6 +16,7 @@ config.host_arch = "@HOST_ARCH@"
 config.python_executable = "@PYTHON_EXECUTABLE@"
 config.test_run_dir = "@CMAKE_CURRENT_BINARY_DIR@"
 config.spirv_tools_have_spirv_as = @SPIRV_TOOLS_SPIRV_AS_FOUND@
+config.spirv_tools_have_spirv_link = @SPIRV_TOOLS_SPIRV_LINK_FOUND@
 config.spirv_tools_have_spirv_val = @SPIRV_TOOLS_SPIRV_VAL_FOUND@
 config.spirv_tools_bin_dir = "@SPIRV_TOOLS_BINDIR@"
 config.spirv_tools_lib_dir = "@SPIRV_TOOLS_LIBDIR@"

llvm-spirv/test/transcoding/linked-program.ll

@@ -0,0 +1,25 @@
+; REQUIRES: spirv-link
+;
+; FIXME This currently crashes when translating back from SPIR-V.
+; XFAIL: *
+;
+; RUN: llvm-as %s -o %t.bc
+; RUN: llvm-spirv %t.bc -o %t.spv
+; RUN: spirv-val %t.spv
+; RUN: spirv-link %t.spv -o %t.linked.spv
+; RUN: llvm-spirv -r %t.linked.spv -o %t.rev.bc
+; RUN: llvm-dis %t.rev.bc -o - | FileCheck %s
+;
+; This checks that SPIR-V programs with global variables are still consumable
+; after spirv-link.
+
+target triple = "spir-unknown-unknown"
+
+@foo = common dso_local local_unnamed_addr addrspace(1) global i32 0, align 4
+; CHECK: @foo = internal addrspace(1) global i32 0, align 4
+
+define dso_local spir_kernel void @bar() local_unnamed_addr {
+entry:
+  store i32 42, i32 addrspace(1)* @foo, align 4
+  ret void
+}