[clang] [clang][Driver][SYCL] Fix SYCLInstallationDetector for compiler installs outside sysroot (PR #211351)

[Nick Sarnie via cfe-commits]

https://github.com/sarnex updated https://github.com/llvm/llvm-project/pull/211351

>From 51f1ab32b82f12b8fedfe3d37973eb96df8e3e83 Mon Sep 17 00:00:00 2001
From: Nick Sarnie <nick.sarnie at intel.com>
Date: Wed, 22 Jul 2026 11:54:06 -0700
Subject: [PATCH 1/2] [clang][Driver][SYCL] Fix SYCLInstallationDetector for
 compiler installs outside sysroot

Signed-off-by: Nick Sarnie <nick.sarnie at intel.com>
---
 clang/lib/Driver/ToolChains/SYCL.cpp              |  7 ++-----
 clang/test/Driver/sycl-rtlib-sysroot-mismatch.cpp | 11 +++++++++++
 2 files changed, 13 insertions(+), 5 deletions(-)
 create mode 100644 clang/test/Driver/sycl-rtlib-sysroot-mismatch.cpp

diff --git a/clang/lib/Driver/ToolChains/SYCL.cpp b/clang/lib/Driver/ToolChains/SYCL.cpp
index d41b5c06da53f..7208a8cac9436 100644
--- a/clang/lib/Driver/ToolChains/SYCL.cpp
+++ b/clang/lib/Driver/ToolChains/SYCL.cpp
@@ -21,7 +21,6 @@ SYCLInstallationDetector::SYCLInstallationDetector(
     : D(D) {
   // When -fsycl is active, locate the SYCL runtime library and record its
   // directory in SYCLRTLibPath for use by the linker.
-  StringRef SysRoot = D.SysRoot;
   SmallString<128> DriverDir(D.Dir);
 
   if (HostTriple.isWindowsMSVCEnvironment() ||
@@ -30,8 +29,7 @@ SYCLInstallationDetector::SYCLInstallationDetector(
     // NOTE: Only checks for LLVMSYCL.lib existence (release variant).
     // Debug vs release library selection happens at link time based on CRT
     // flags.
-    if (DriverDir.starts_with(SysRoot) &&
-        Args.hasFlag(options::OPT_fsycl, options::OPT_fno_sycl, false)) {
+    if (Args.hasFlag(options::OPT_fsycl, options::OPT_fno_sycl, false)) {
       SmallString<128> LibDir(DriverDir);
       llvm::sys::path::append(LibDir, "..", "lib");
 
@@ -52,8 +50,7 @@ SYCLInstallationDetector::SYCLInstallationDetector(
     SmallString<128> FlatLibPath(DriverDir);
     llvm::sys::path::append(FlatLibPath, "..", "lib", "libLLVMSYCL.so");
 
-    if (DriverDir.starts_with(SysRoot) &&
-        Args.hasFlag(options::OPT_fsycl, options::OPT_fno_sycl, false)) {
+    if (Args.hasFlag(options::OPT_fsycl, options::OPT_fno_sycl, false)) {
       // LLVM_ENABLE_PER_TARGET_RUNTIME_DIR=ON: library is in lib/<triple>/
       if (D.getVFS().exists(LibPath))
         llvm::sys::path::append(DriverDir, "..", "lib", HostTriple.str());
diff --git a/clang/test/Driver/sycl-rtlib-sysroot-mismatch.cpp b/clang/test/Driver/sycl-rtlib-sysroot-mismatch.cpp
new file mode 100644
index 0000000000000..a0edbaa425510
--- /dev/null
+++ b/clang/test/Driver/sycl-rtlib-sysroot-mismatch.cpp
@@ -0,0 +1,11 @@
+// REQUIRES: system-linux && symlinks
+
+// Verify we still generate a path to libLLVMSYCL.so even with sysroot set.
+
+// RUN: rm -rf %t && mkdir -p %t/bin %t/lib
+// RUN: touch %t/lib/libLLVMSYCL.so
+// RUN: ln -s %clang %t/bin/clang
+// RUN: %t/bin/clang -### -no-canonical-prefixes --target=x86_64-unknown-linux-gnu -fsycl --sysroot=/nonexistent-prefix %s 2>&1 \
+// RUN:   | FileCheck %s
+
+// CHECK: "{{.*}}/bin/../lib/libLLVMSYCL.so"

>From b9804bb149b1311431d7d3ebcb104322aa25be62 Mon Sep 17 00:00:00 2001
From: Nick Sarnie <nick.sarnie at intel.com>
Date: Fri, 24 Jul 2026 09:05:50 -0700
Subject: [PATCH 2/2] add test for per-target-runtime-dir layout

Signed-off-by: Nick Sarnie <nick.sarnie at intel.com>
---
 clang/test/Driver/sycl-rtlib-sysroot-mismatch.cpp | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/clang/test/Driver/sycl-rtlib-sysroot-mismatch.cpp b/clang/test/Driver/sycl-rtlib-sysroot-mismatch.cpp
index a0edbaa425510..87ed4ba1f9ff7 100644
--- a/clang/test/Driver/sycl-rtlib-sysroot-mismatch.cpp
+++ b/clang/test/Driver/sycl-rtlib-sysroot-mismatch.cpp
@@ -6,6 +6,13 @@
 // RUN: touch %t/lib/libLLVMSYCL.so
 // RUN: ln -s %clang %t/bin/clang
 // RUN: %t/bin/clang -### -no-canonical-prefixes --target=x86_64-unknown-linux-gnu -fsycl --sysroot=/nonexistent-prefix %s 2>&1 \
-// RUN:   | FileCheck %s
+// RUN:   | FileCheck -check-prefix=CHECK-FLAT %s
 
-// CHECK: "{{.*}}/bin/../lib/libLLVMSYCL.so"
+// RUN: rm -rf %t && mkdir -p %t/bin %t/lib/x86_64-unknown-linux-gnu
+// RUN: touch %t/lib/x86_64-unknown-linux-gnu/libLLVMSYCL.so
+// RUN: ln -s %clang %t/bin/clang
+// RUN: %t/bin/clang -### -no-canonical-prefixes --target=x86_64-unknown-linux-gnu -fsycl --sysroot=/nonexistent-prefix %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-PER-TARGET %s
+
+// CHECK-FLAT: "{{.*}}/bin/../lib/libLLVMSYCL.so"
+// CHECK-PER-TARGET: "{{.*}}/bin/../lib/x86_64-unknown-linux-gnu/libLLVMSYCL.so"