[SYCL][Driver] Disable "early" optimizations for Intel FPGA by default (#2331)

Enabling standard LLVM passes for SPIR target by default might have
negative impact on the metadata added specifically for Intel FPGA
target. We might switch it back to "ON" by default after more thorough
validation.

Author: bader

clang/lib/Driver/ToolChains/Clang.cpp

@@ -4103,8 +4103,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                      false))
       CmdArgs.push_back("-fsycl-explicit-simd");
 
+    // Default value for FPGA is false, for all other targets is true.
     if (!Args.hasFlag(options::OPT_fsycl_early_optimizations,
-                      options::OPT_fno_sycl_early_optimizations, true))
+                      options::OPT_fno_sycl_early_optimizations,
+                      Triple.getSubArch() != llvm::Triple::SPIRSubArch_fpga))
       CmdArgs.push_back("-fno-sycl-early-optimizations");
     else if (RawTriple.isSPIR()) {
       // Set `sycl-opt` option to configure LLVM passes for SPIR target

clang/test/Driver/sycl-device-optimizations.cpp

@@ -3,12 +3,16 @@
 // RUN:   | FileCheck -check-prefix=CHECK-DEFAULT %s
 // RUN:   %clang -### -fsycl -fsycl-device-only %s 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHECK-DEFAULT %s
+// RUN:   %clang -### -fsycl -fintelfpga -fsycl-early-optimizations %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-DEFAULT %s
 // CHECK-DEFAULT-NOT: "-fno-sycl-early-optimizations"
 // CHECK-DEFAULT-NOT: "-disable-llvm-passes"
 
 /// Check "-fno-sycl-early-optimizations" is passed to the front-end:
 // RUN:   %clang -### -fsycl -fno-sycl-early-optimizations %s 2>&1 \
-// RUN:   | FileCheck -check-prefix=CHECK-NO-SYCL-STD-OPTS %s
+// RUN:   | FileCheck -check-prefix=CHECK-NO-SYCL-EARLY-OPTS %s
 // RUN:   %clang -### -fsycl -fsycl-device-only -fno-sycl-early-optimizations %s 2>&1 \
-// RUN:   | FileCheck -check-prefix=CHECK-NO-SYCL-STD-OPTS %s
-// CHECK-NO-SYCL-STD-OPTS: "-fno-sycl-early-optimizations"
+// RUN:   | FileCheck -check-prefix=CHECK-NO-SYCL-EARLY-OPTS %s
+// RUN:   %clang -### -fsycl -fintelfpga %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=CHECK-NO-SYCL-EARLY-OPTS %s
+// CHECK-NO-SYCL-EARLY-OPTS: "-fno-sycl-early-optimizations"