[Driver][SYCL] Set default device code split mode to off for FPGA (#4893)

The Driver passes default device code split mode (-split=auto) to
sycl-post-link when -fsycl-device-code-split is not set. This should
not be applied for FPGA, because FPGA is using SYCL_EXTERNAL for
some of their library configurations but auto device code split mode
impacts this behavior.

Signed-off-by: Qichao Gu qichao.gu@intel.com

Author: qichaogu

clang/lib/Driver/ToolChains/Clang.cpp

@@ -9037,8 +9037,9 @@ void SYCLPostLink::ConstructJob(Compilation &C, const JobAction &JA,
       addArgs(CmdArgs, TCArgs, {"-split=auto"});
     else { // Device code split is off
     }
-  } else {
-    // auto is the default split mode
+  } else if (getToolChain().getTriple().getArchName() != "spir64_fpga") {
+    // for FPGA targets, off is the default split mode,
+    // otherwise auto is the default split mode
     addArgs(CmdArgs, TCArgs, {"-split=auto"});
   }
 

clang/test/Driver/sycl-offload-with-split.c

@@ -312,6 +312,16 @@
 // RUN:    | FileCheck %s -check-prefixes=CHK-NO-SPLIT
 // CHK-NO-SPLIT-NOT: sycl-post-link{{.*}} -split{{.*}}
 
+// Check no device code split mode is passed to sycl-post-link when -fsycl-device-code-split is not set and the target is FPGA
+// RUN:   %clang -### -fsycl -fsycl-targets=spir64_fpga-unknown-unknown %s 2>&1 | FileCheck %s -check-prefixes=CHK-NO-SPLIT
+
+// Check device code split mode is honored when -fsycl-device-code-split is set and the target is FPGA
+// RUN:   %clang -### -fsycl -fsycl-device-code-split -fsycl-targets=spir64_fpga-unknown-unknown %s 2>&1 | FileCheck %s -check-prefixes=CHK-AUTO
+// RUN:   %clang -### -fsycl -fsycl-device-code-split=auto -fsycl-targets=spir64_fpga-unknown-unknown %s 2>&1 | FileCheck %s -check-prefixes=CHK-AUTO
+// RUN:   %clang -### -fsycl -fsycl-device-code-split=per_kernel -fsycl-targets=spir64_fpga-unknown-unknown %s 2>&1 | FileCheck %s -check-prefixes=CHK-ONE-KERNEL
+// RUN:   %clang -### -fsycl -fsycl-device-code-split=per_source -fsycl-targets=spir64_fpga-unknown-unknown %s 2>&1 | FileCheck %s -check-prefixes=CHK-PER-SOURCE
+// RUN:   %clang -### -fsycl -fsycl-device-code-split=off -fsycl-targets=spir64_fpga-unknown-unknown %s 2>&1 | FileCheck %s -check-prefixes=CHK-NO-SPLIT
+
 // Check ESIMD device code split.
 // RUN:   %clang    -### -fsycl %s 2>&1 | FileCheck %s -check-prefixes=CHK-ESIMD-SPLIT
 // RUN:   %clang_cl -### -fsycl %s 2>&1 | FileCheck %s -check-prefixes=CHK-ESIMD-SPLIT