[Driver][SYCL][FPGA] Do not optimize after wrapping an object (#2695)

When performing -fsycl-link=early and generating an archive for
FPGA, the host object ended up being truncated in the archive.
After wrapping the host object (which generates a .bc file), that
wrapped object goes through an additional compilation step. When
enabling optimizations (-O2, etc), the wrapped host object would
be optimized away, causing problems when going from the early
device to either exe or image.  Do not pass the optimization option
during this specific step.

Author: mdtoguchi

clang/lib/Driver/ToolChains/Clang.cpp

@@ -4013,6 +4013,17 @@ static void RenderDebugOptions(const ToolChain &TC, const Driver &D,
   RenderDebugInfoCompressionArgs(Args, CmdArgs, D, TC);
 }
 
+/// Check whether the given input tree contains any wrapper actions
+static bool ContainsWrapperAction(const Action *A) {
+  if (isa<OffloadWrapperJobAction>(A))
+    return true;
+  for (const auto &AI : A->inputs())
+    if (ContainsWrapperAction(AI))
+      return true;
+
+  return false;
+}
+
 void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                          const InputInfo &Output, const InputInfoList &Inputs,
                          const ArgList &Args, const char *LinkingOutput) const {
@@ -5177,13 +5188,17 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // preprocessed inputs and configure concludes that -fPIC is not supported.
   Args.ClaimAllArgs(options::OPT_D);
 
+  bool SkipO =
+      Args.hasArg(options::OPT_fsycl_link_EQ) && ContainsWrapperAction(&JA);
+  const Arg *OArg = Args.getLastArg(options::OPT_O_Group);
   // Manually translate -O4 to -O3; let clang reject others.
-  if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {
-    if (A->getOption().matches(options::OPT_O4)) {
+  // When compiling a wrapped binary, do not optimize.
+  if (!SkipO && OArg) {
+    if (OArg->getOption().matches(options::OPT_O4)) {
       CmdArgs.push_back("-O3");
       D.Diag(diag::warn_O4_is_O3);
     } else {
-      A->render(Args, CmdArgs);
+      OArg->render(Args, CmdArgs);
     }
   }
 

clang/test/Driver/sycl-offload-intelfpga.cpp

@@ -23,7 +23,7 @@
 // RUN:  touch %t.o
 // RUN:  %clangxx -### -target x86_64-unknown-linux-gnu -fsycl -fno-sycl-device-lib=all -fintelfpga -fsycl-link %t.o -o libfoo.a 2>&1 \
 // RUN:  | FileCheck -check-prefixes=CHK-FPGA-LINK,CHK-FPGA-EARLY %s
-// RUN:  %clangxx -### -target x86_64-unknown-linux-gnu -fsycl  -fno-sycl-device-lib=all -fintelfpga -fsycl-link=early %t.o -o libfoo.a 2>&1 \
+// RUN:  %clangxx -### -O2 -target x86_64-unknown-linux-gnu -fsycl  -fno-sycl-device-lib=all -fintelfpga -fsycl-link=early %t.o -o libfoo.a 2>&1 \
 // RUN:  | FileCheck -check-prefixes=CHK-FPGA-LINK,CHK-FPGA-EARLY %s
 // RUN:  %clangxx -### -target x86_64-unknown-linux-gnu -fsycl -fno-sycl-device-lib=all -fintelfpga  -fsycl-link=image %t.o -o libfoo.a 2>&1 \
 // RUN:  | FileCheck -check-prefixes=CHK-FPGA-LINK,CHK-FPGA-IMAGE %s
@@ -38,7 +38,8 @@
 // CHK-FPGA-LINK: clang-offload-wrapper{{.*}} "-o=[[WRAPOUT:.+\.bc]]" "-host=x86_64-unknown-linux-gnu" {{.*}} "-kind=sycl"
 // CHK-FPGA-LINK: llc{{.*}} "-o" "[[OBJOUTDEV:.+\.o]]" "[[WRAPOUT]]"
 // CHK-FPGA-EARLY: clang-offload-wrapper{{.*}} "-host" "x86_64-unknown-linux-gnu" "-o" "[[WRAPOUTHOST:.+\.bc]]" "-kind=host"
-// CHK-FPGA-EARLY: clang{{.*}} "-o" "[[OBJOUT:.+\.o]]" {{.*}} "[[WRAPOUTHOST]]"
+// CHK-FPGA-EARLY-NOT: clang{{.*}} "-triple" "x86_64-unknown-linux-gnu" {{.*}} "-O2"
+// CHK-FPGA-EARLY: "-o" "[[OBJOUT:.+\.o]]" {{.*}} "[[WRAPOUTHOST]]"
 // CHK-FPGA-EARLY: llvm-ar{{.*}} "cr" "libfoo.a" "[[OBJOUT]]" "[[OBJOUTDEV]]"
 // CHK-FPGA-IMAGE: llvm-ar{{.*}} "cr" "libfoo.a" "[[INPUT]]" "[[OBJOUTDEV]]"