[RISCV] Fix the include search path order between sysroot and resource folder (Recommit again)

Resource folder[1] should include before sysroot[2] in general (Linux clang
toolchain, BareMetal clang toolchain, and GCC using that order), and that
prevent sysroot's header file override resource folder's one, this change is
reference from BareMetal::[email protected][3].

And also fix the behavior of `-nobuiltininc`.

[1] Include path from resource folder is something like this: `<toolchain-path>/lib/clang/13.0.0/include/`
[2] Include path from sysroot is something like this: `<toolchain-path>/riscv32-unknown-elf/include`
[3] https://github.com/llvm/llvm-project/blob/llvmorg-13.0.1/clang/lib/Driver/ToolChains/BareMetal.cpp#L193

Reviewed By: asb

Differential Revision: https://reviews.llvm.org/D119837

The recommit fixes the Windows build failure due to path issue.

Author: kito-cheng

clang/lib/Driver/ToolChains/RISCVToolchain.cpp

@@ -98,6 +98,12 @@ void RISCVToolChain::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
   if (DriverArgs.hasArg(options::OPT_nostdinc))
     return;
 
+  if (!DriverArgs.hasArg(options::OPT_nobuiltininc)) {
+    SmallString<128> Dir(getDriver().ResourceDir);
+    llvm::sys::path::append(Dir, "include");
+    addSystemInclude(DriverArgs, CC1Args, Dir.str());
+  }
+
   if (!DriverArgs.hasArg(options::OPT_nostdlibinc)) {
     SmallString<128> Dir(computeSysRoot());
     llvm::sys::path::append(Dir, "include");

clang/test/Driver/Inputs/resource_dir/include/.keep

@@ -197,6 +197,20 @@
 // C-RV32-RTLIB-COMPILERRT-ILP32: "--start-group" "-lc" "-lgloss" "--end-group" "{{.*}}libclang_rt.builtins-riscv32.a"
 // C-RV32-RTLIB-COMPILERRT-ILP32: "{{.*}}clang_rt.crtend-riscv32.o"
 
+// RUN: %clang %s -### -no-canonical-prefixes -target riscv32 \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_riscv32_tree \
+// RUN:   -resource-dir=%s/Inputs/resource_dir 2>&1 \
+// RUN:   | FileCheck -check-prefix=RESOURCE-INC %s
+// RESOURCE-INC: "-internal-isystem" "{{.*}}/Inputs/resource_dir{{/|\\\\}}include"
+// RESOURCE-INC: "-internal-isystem" "{{.*}}/basic_riscv32_tree{{.*}}riscv32-unknown-elf{{/|\\\\}}include"
+
+// RUN: %clang %s -### -no-canonical-prefixes -target riscv32 \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_riscv32_tree \
+// RUN:   -resource-dir=%s/Inputs/resource_dir -nobuiltininc 2>&1 \
+// RUN:   | FileCheck -check-prefix=NO-RESOURCE-INC %s
+// NO-RESOURCE-INC-NOT: "-internal-isystem" "{{.*}}/Inputs/resource_dir{{/|\\\\}}include"
+// NO-RESOURCE-INC: "-internal-isystem" "{{.*}}/basic_riscv32_tree/{{.*}}riscv32-unknown-elf{{/|\\\\}}include"
+
 // RUN: %clang -target riscv32 %s -emit-llvm -S -o - | FileCheck %s
 
 typedef __builtin_va_list va_list;

clang/test/Driver/riscv32-toolchain.c

@@ -153,6 +153,20 @@
 // C-RV64-RTLIB-COMPILERRT-LP64: "--start-group" "-lc" "-lgloss" "--end-group" "{{.*}}libclang_rt.builtins-riscv64.a"
 // C-RV64-RTLIB-COMPILERRT-LP64: "{{.*}}clang_rt.crtend-riscv64.o"
 
+// RUN: %clang %s -### -no-canonical-prefixes -target riscv64 \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_riscv64_tree \
+// RUN:   -resource-dir=%s/Inputs/resource_dir 2>&1 \
+// RUN:   | FileCheck -check-prefix=RESOURCE-INC %s
+// RESOURCE-INC: "-internal-isystem" "{{.*}}/Inputs/resource_dir{{/|\\\\}}include"
+// RESOURCE-INC: "-internal-isystem" "{{.*}}/basic_riscv64_tree/{{.*}}riscv64-unknown-elf{{/|\\\\}}include"
+
+// RUN: %clang %s -### -no-canonical-prefixes -target riscv64 \
+// RUN:   --gcc-toolchain=%S/Inputs/basic_riscv64_tree \
+// RUN:   -resource-dir=%s/Inputs/resource_dir -nobuiltininc 2>&1 \
+// RUN:   | FileCheck -check-prefix=NO-RESOURCE-INC %s
+// NO-RESOURCE-INC-NOT: "-internal-isystem" "{{.*}}Inputs/resource_dir{{/|\\\\}}include"
+// NO-RESOURCE-INC: "-internal-isystem" "{{.*}}/basic_riscv64_tree/{{.*}}riscv64-unknown-elf{{/|\\\\}}include"
+
 // RUN: %clang -target riscv64 %s -emit-llvm -S -o - | FileCheck %s
 
 typedef __builtin_va_list va_list;