[OpenCL] Do not include default header for preprocessor output as input

[yaxunl]

Summary

When clang driver is used with -save-temps to compile OpenCL program,
clang driver first launches clang -cc1 -E to generate preprocessor expansion output,
then launches clang -cc1 with the generated preprocessor expansion output as input
to generate LLVM IR.

Currently clang by default passes "-finclude-default-header" "-fdeclare-opencl-builtins"
in both steps, which causes default header included again in the second step, which
causes error.

This patch let clang not to include default header when input type is preprocessor expansion
output, which fixes the issue.

[yaxunl]

I am not quite sure about whether "-fdeclare-opencl-builtins" should be kept when input is preprocessor output. Suggestions? Thanks.

[yaxunl]

In D104800#2836594, @yaxunl wrote:

I am not quite sure about whether "-fdeclare-opencl-builtins" should be kept when input is preprocessor output. Suggestions? Thanks.

The question is that whether those builtins declared through "-fdeclare-opencl-builtins" will be in preprocessor expansion output. It seems not. If so, we still need "-fdeclare-opencl-builtins" when input type is preprocessor expansion output.

[Anastasia]

LGTM! Thanks

I agree we should have the same behavior for both options. Technically -finclude-default-header could be added in both steps but it is only effective in parsing the sources and does nothing otherwise. But it seems cleaner to align it with the header include option.

clang/lib/Driver/ToolChains/Clang.cpp

if (Arg *A = Args.getLastArg(options::OPT_cl_std_EQ)) {
     CmdArgs.push_back(Args.MakeArgString(CLStdStr));
   }
 
   for (const auto &Arg : ForwardedArguments)
     if (const auto *A = Args.getLastArg(Arg))
       CmdArgs.push_back(Args.MakeArgString(A->getOption().getPrefixedName()));
 
   // Only add the default headers if we are compiling OpenCL sources.
-  if ((types::isOpenCL(InputType) || Args.hasArg(options::OPT_cl_std_EQ)) &&
+  if ((types::isOpenCL(InputType) ||
+       (Args.hasArg(options::OPT_cl_std_EQ) && types::isSrcFile(InputType))) &&
       !Args.hasArg(options::OPT_cl_no_stdinc)) {
     CmdArgs.push_back("-finclude-default-header");
     CmdArgs.push_back("-fdeclare-opencl-builtins");
   }
 }
 
 static void RenderARCMigrateToolOptions(const Driver &D, const ArgList &Args,
                                         ArgStringList &CmdArgs) {

clang/test/Driver/amdgpu-toolchain-opencl.cl

 // RUN: %clang -### -target amdgcn-amd-amdhsa-opencl -x cl -c -emit-llvm -mcpu=fiji -O0 %s 2>&1 | FileCheck -check-prefix=CHECK_O0 %s
 // RUN: %clang -### -target amdgcn-amd-amdhsa-opencl -x cl -c -emit-llvm -mcpu=fiji -O1 %s 2>&1 | FileCheck -check-prefix=CHECK_O1 %s
 // RUN: %clang -### -target amdgcn-amd-amdhsa-opencl -x cl -c -emit-llvm -mcpu=fiji -O2 %s 2>&1 | FileCheck -check-prefix=CHECK_O2 %s
 // RUN: %clang -### -target amdgcn-amd-amdhsa-opencl -x cl -c -emit-llvm -mcpu=fiji -O3 %s 2>&1 | FileCheck -check-prefix=CHECK_O3 %s
 // RUN: %clang -### -target amdgcn-amd-amdhsa-opencl -x cl -c -emit-llvm -mcpu=fiji -O4 %s 2>&1 | FileCheck -check-prefix=CHECK_O4 %s
 // RUN: %clang -### -target amdgcn-amd-amdhsa-opencl -x cl -c -emit-llvm -mcpu=fiji -O5 %s 2>&1 | FileCheck -check-prefix=CHECK_O5 %s
 // RUN: %clang -### -target amdgcn-amd-amdhsa-opencl -x cl -c -emit-llvm -mcpu=fiji -Og %s 2>&1 | FileCheck -check-prefix=CHECK_Og %s
 // RUN: %clang -### -target amdgcn-amd-amdhsa-opencl -x cl -c -emit-llvm -mcpu=fiji -Ofast %s 2>&1 | FileCheck -check-prefix=CHECK_Ofast %s
 // RUN: %clang -### -target amdgcn-amd-amdhsa-opencl -x cl -c -emit-llvm -mcpu=fiji %s 2>&1 | FileCheck -check-prefix=CHECK_O_DEFAULT %s
+
+// Check default include file is not included for preprocessor output.
+
+// RUN: %clang -### -target amdgcn-amd-amdhsa-opencl -x cl -c -emit-llvm -mcpu=fiji %s 2>&1 | FileCheck -check-prefix=CHK-INC %s
+// RUN: %clang -### -target amdgcn-amd-amdhsa-opencl -x cl -c -emit-llvm -mcpu=fiji -save-temps %s 2>&1 | FileCheck -check-prefix=CHK-INC %s
+
 // CHECK_O0: clang{{.*}} "-O0"
 // CHECK_O1: clang{{.*}} "-O1"
 // CHECK_O2: clang{{.*}} "-O2"
 // CHECK_O3: clang{{.*}} "-O3"
 // CHECK_O4: clang{{.*}} "-O3"
 // CHECK_O5: clang{{.*}} "-O5"
 // CHECK_Og: clang{{.*}} "-Og"
 // CHECK_Ofast: {{.*}}clang{{.*}} "-Ofast"
 // CHECK_O_DEFAULT: clang{{.*}} "-O3"
 
+// CHK-INC: clang{{.*}} "-cc1" {{.*}}"-finclude-default-header" "-fdeclare-opencl-builtins" {{.*}}"-x" "cl"
+// CHK-INC-NOT: clang{{.*}} "-cc1" {{.*}}"-finclude-default-header" "-fdeclare-opencl-builtins" {{.*}}"-x" "cpp-output"