Specify GCC prefix in LLVM-based compilers (#33146)

* spack.compiler.Compiler: introduce prefix property

We currently don't really have something that gives the GCC install
path, which is used by many LLVM-based compilers (llvm, llvm-amdgpu,
nvhpc, ...) to fix the GCC toolchain once and for all.

This `prefix` property is dynamic in the sense that it queries the
compiler itself. This is necessary because it's not easy to deduce the
install path from the `cc` property (might be a symlink, might be a
filename like `gcc` which works by having the compiler load a module
that sets the PATH variable, might be a generic compiler wrapper based
on environment variables like on cray...).

With this property introduced, we can clean up some recipes that have
the logic repeated for GCC.

* intel-oneapi-compilers: set --gcc-sysroot to %gcc prefix

4 files changed, 16 insertions, 35 deletions

diff --git a/var/spack/repos/builtin/packages/intel-oneapi-compilers/package.py b/var/spack/repos/builtin/packages/intel-oneapi-compilers/package.py
index a4e85c77de..7f601fc3d1 100644
--- a/var/spack/repos/builtin/packages/intel-oneapi-compilers/package.py
+++ b/var/spack/repos/builtin/packages/intel-oneapi-compilers/package.py
@@ -5,6 +5,7 @@
 
 import platform
 
+import spack.compilers
 from spack.build_environment import dso_suffix
 from spack.package import *
 
@@ -113,6 +114,15 @@ class IntelOneapiCompilers(IntelOneApiPackage):
 
     depends_on("patchelf", type="build")
 
+    # TODO: effectively gcc is a direct dependency of intel-oneapi-compilers, but we
+    # cannot express that properly. For now, add conflicts for non-gcc compilers
+    # instead.
+    for __compiler in spack.compilers.supported_compilers():
+        if __compiler != "gcc":
+            conflicts(
+                "%{0}".format(__compiler), msg="intel-oneapi-compilers must be installed with %gcc"
+            )
+
     if platform.system() == "Linux":
         for v in linux_versions:
             version(v["version"], expand=False, **v["cpp"])
@@ -186,7 +196,9 @@ class IntelOneapiCompilers(IntelOneApiPackage):
         # TODO: it is unclear whether we should really use all elements of
         #  _ld_library_path because it looks like the only rpath that needs to be
         #  injected is self.component_prefix.linux.compiler.lib.intel64_lin.
-        flags = " ".join(["-Wl,-rpath,{0}".format(d) for d in self._ld_library_path()])
+        flags_list = ["-Wl,-rpath,{}".format(d) for d in self._ld_library_path()]
+        flags_list.append("--gcc-toolchain={}".format(self.compiler.prefix))
+        flags = " ".join(flags_list)
         for cmp in [
             "icx",
             "icpx",
diff --git a/var/spack/repos/builtin/packages/llvm-amdgpu/package.py b/var/spack/repos/builtin/packages/llvm-amdgpu/package.py
index f6192e6080..6002351a64 100644
--- a/var/spack/repos/builtin/packages/llvm-amdgpu/package.py
+++ b/var/spack/repos/builtin/packages/llvm-amdgpu/package.py
@@ -234,18 +234,7 @@ class LlvmAmdgpu(CMakePackage):
 
         # Get the GCC prefix for LLVM.
         if self.compiler.name == "gcc":
-            compiler = Executable(self.compiler.cc)
-            gcc_output = compiler("-print-search-dirs", output=str, error=str)
-
-            gcc_prefix = ""
-            for line in gcc_output.splitlines():
-                if line.startswith("install:"):
-                    # Get path and strip any whitespace
-                    # (causes oddity with ancestor)
-                    gcc_prefix = line.split(":")[1].strip()
-                    gcc_prefix = ancestor(gcc_prefix, 4)
-                    break
-            args.append(self.define("GCC_INSTALL_PREFIX", gcc_prefix))
+            args.append(self.define("GCC_INSTALL_PREFIX", self.compiler.prefix))
 
         return args
 
diff --git a/var/spack/repos/builtin/packages/llvm-doe/package.py b/var/spack/repos/builtin/packages/llvm-doe/package.py
index 29bdc912b7..e2ec14fa0d 100644
--- a/var/spack/repos/builtin/packages/llvm-doe/package.py
+++ b/var/spack/repos/builtin/packages/llvm-doe/package.py
@@ -582,17 +582,7 @@ class LlvmDoe(CMakePackage, CudaPackage):
                 cmake_args.append("-DLIBOMP_USE_ARGOBOTS=ON")
 
         if self.compiler.name == "gcc":
-            compiler = Executable(self.compiler.cc)
-            gcc_output = compiler("-print-search-dirs", output=str, error=str)
-
-            for line in gcc_output.splitlines():
-                if line.startswith("install:"):
-                    # Get path and strip any whitespace
-                    # (causes oddity with ancestor)
-                    gcc_prefix = line.split(":")[1].strip()
-                    gcc_prefix = ancestor(gcc_prefix, 4)
-                    break
-            cmake_args.append(define("GCC_INSTALL_PREFIX", gcc_prefix))
+            cmake_args.append(define("GCC_INSTALL_PREFIX", self.compiler.prefix))
 
         # if spec.satisfies("platform=cray") or spec.satisfies("platform=linux"):
         #     cmake_args.append("-DCMAKE_BUILD_WITH_INSTALL_RPATH=1")
diff --git a/var/spack/repos/builtin/packages/llvm/package.py b/var/spack/repos/builtin/packages/llvm/package.py
index 5751629f5f..d7958bd6f8 100644
--- a/var/spack/repos/builtin/packages/llvm/package.py
+++ b/var/spack/repos/builtin/packages/llvm/package.py
@@ -721,17 +721,7 @@ class Llvm(CMakePackage, CudaPackage):
         cmake_args.append(from_variant("LIBOMP_TSAN_SUPPORT", "omp_tsan"))
 
         if self.compiler.name == "gcc":
-            compiler = Executable(self.compiler.cc)
-            gcc_output = compiler("-print-search-dirs", output=str, error=str)
-
-            for line in gcc_output.splitlines():
-                if line.startswith("install:"):
-                    # Get path and strip any whitespace
-                    # (causes oddity with ancestor)
-                    gcc_prefix = line.split(":")[1].strip()
-                    gcc_prefix = ancestor(gcc_prefix, 4)
-                    break
-            cmake_args.append(define("GCC_INSTALL_PREFIX", gcc_prefix))
+            cmake_args.append(define("GCC_INSTALL_PREFIX", self.compiler.prefix))
 
         if self.spec.satisfies("~code_signing platform=darwin"):
             cmake_args.append(define("LLDB_USE_SYSTEM_DEBUGSERVER", True))