[SYCL][Driver] Add deprecated warning for backend GRF options on PVC (#12029)

With the `-ftarget-register-alloc-mode` option, the user doesn't need to
pass IGC flags to the compiler to set the GRF mode. On PVC, emit a
warning in the most common case to suggest the user use the new option.
This doesn't catch every case because the `-device` syntax is
complicated, but it can help in the most common use case.

---------

Signed-off-by: Sarnie, Nick <[email protected]>

Author: sarnex

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -399,6 +399,9 @@ def err_drv_fsycl_wrong_optimization_options : Error<
 def warn_drv_fsycl_add_default_spec_consts_image_flag_in_non_AOT : Warning<
   "-fsycl-add-default-spec-consts-image flag has an effect only in Ahead of Time Compilation mode (AOT).">,
   InGroup<SyclTarget>;
+def warn_drv_ftarget_register_alloc_mode_pvc : Warning<
+  "using '%0' to set GRF mode on PVC hardware is deprecated; use '-ftarget-register-alloc-mode=pvc:%1'">,
+  InGroup<Deprecated>;
 def err_drv_multiple_target_with_forced_target : Error<
   "multiple target usage with '%0' is not supported with '%1'">;
 def err_drv_failed_to_deduce_target_from_arch : Error<

clang/lib/Driver/ToolChains/SYCL.cpp

@@ -781,12 +781,15 @@ void SYCL::fpga::BackendCompiler::ConstructJob(
     C.addCommand(std::move(Cmd));
 }
 
+static llvm::StringMap<StringRef> GRFModeFlagMap{
+    {"auto", "-ze-intel-enable-auto-large-GRF-mode"},
+    {"small", "-ze-intel-128-GRF-per-thread"},
+    {"large", "-ze-opt-large-register-file"}};
+
 StringRef SYCL::gen::getGenGRFFlag(StringRef GRFMode) {
-  return llvm::StringSwitch<StringRef>(GRFMode)
-      .Case("auto", "-ze-intel-enable-auto-large-GRF-mode")
-      .Case("small", "-ze-intel-128-GRF-per-thread")
-      .Case("large", "-ze-opt-large-register-file")
-      .Default("");
+  if (!GRFModeFlagMap.contains(GRFMode))
+    return "";
+  return GRFModeFlagMap[GRFMode];
 }
 
 void SYCL::gen::BackendCompiler::ConstructJob(Compilation &C,
@@ -1100,6 +1103,26 @@ void SYCLToolChain::TranslateGPUTargetOpt(const llvm::opt::ArgList &Args,
   }
 }
 
+static void WarnForDeprecatedBackendOpts(const Driver &D,
+                                         const llvm::Triple &Triple,
+                                         StringRef Device, StringRef ArgString,
+                                         const llvm::opt::Arg *A) {
+  // Suggest users passing GRF backend opts on PVC to use
+  // -ftarget-register-alloc-mode and
+
+  if (!ArgString.contains("-device pvc") && !Device.contains("pvc"))
+    return;
+  // Make sure to only warn for once for gen targets as the translate
+  // options tree is called twice but only the second time has the
+  // device set.
+  if (Triple.isSPIR() && Triple.getSubArch() == llvm::Triple::SPIRSubArch_gen &&
+      !A->isClaimed())
+    return;
+  for (const auto &[Mode, Flag] : GRFModeFlagMap)
+    if (ArgString.contains(Flag))
+      D.Diag(diag::warn_drv_ftarget_register_alloc_mode_pvc) << Flag << Mode;
+}
+
 // Expects a specific type of option (e.g. -Xsycl-target-backend) and will
 // extract the arguments.
 void SYCLToolChain::TranslateTargetOpt(const llvm::opt::ArgList &Args,
@@ -1143,7 +1166,8 @@ void SYCLToolChain::TranslateTargetOpt(const llvm::opt::ArgList &Args,
     } else
       // Triple found, add the next argument in line.
       ArgString = A->getValue(1);
-
+    WarnForDeprecatedBackendOpts(getDriver(), getTriple(), Device, ArgString,
+                                 A);
     parseTargetOpts(ArgString, Args, CmdArgs);
     A->claim();
   }
@@ -1313,12 +1337,15 @@ void SYCLToolChain::TranslateBackendTargetArgs(
     if (A->getOption().matches(options::OPT_Xs)) {
       // Take the arg and create an option out of it.
       CmdArgs.push_back(Args.MakeArgString(Twine("-") + A->getValue()));
+      WarnForDeprecatedBackendOpts(getDriver(), Triple, Device, A->getValue(),
+                                   A);
       A->claim();
       continue;
     }
     if (A->getOption().matches(options::OPT_Xs_separate)) {
       StringRef ArgString(A->getValue());
       parseTargetOpts(ArgString, Args, CmdArgs);
+      WarnForDeprecatedBackendOpts(getDriver(), Triple, Device, ArgString, A);
       A->claim();
       continue;
     }

clang/test/Driver/sycl-ftarget-register-alloc-mode-warning.cpp

@@ -0,0 +1,22 @@
+// Test warning SYCL -ftarget-register-alloc-mode for pvc
+
+// RUN: %clang -fsycl -Xs "-device pvc -ze-opt-large-register-file" -### %s 2>&1 | FileCheck -check-prefix=LARGE %s
+// RUN: %clang -fsycl -Xs "-device pvc -ze-intel-128-GRF-per-thread" -### %s 2>&1 | FileCheck -check-prefix=SMALL %s
+// RUN: %clang -fsycl -Xs "-ze-intel-enable-auto-large-GRF-mode -device pvc" -### %s 2>&1 | FileCheck -check-prefix=AUTO %s
+
+// RUN: %clang -fsycl -fsycl-targets=intel_gpu_pvc -Xs "-ze-opt-large-register-file" -### %s 2>&1 | FileCheck -check-prefix=LARGE %s
+
+// RUN: %clang -fsycl -fsycl-targets=intel_gpu_pvc -Xs"-ze-opt-large-register-file" -### %s 2>&1 | FileCheck -check-prefix=LARGE %s
+
+// RUN: %clang -fsycl -Xsycl-target-backend=spir64 "-device pvc -ze-intel-128-GRF-per-thread" -### %s 2>&1 | FileCheck -check-prefix=SMALL %s
+
+// RUN: %clang -fsycl -fsycl-targets=intel_gpu_pvc -Xsycl-target-backend "-ze-opt-large-register-file" -### %s 2>&1 | FileCheck -check-prefix=LARGE %s
+
+// RUN: %clang -fsycl -fsycl-targets=spir64_gen -Xs "-ze-opt-large-register-file -device pvc" -### %s 2>&1 | FileCheck -check-prefix=LARGE %s
+
+// RUN: %clang -fsycl -fsycl-targets=spir64,spir64_gen -Xsycl-target-backend=spir64 "-ze-opt-large-register-file -device pvc" \
+// RUN: -Xsycl-target-backend=spir64_gen "-ze-intel-enable-auto-large-GRF-mode -device pvc" -### %s 2>&1 | FileCheck -check-prefixes=LARGE,AUTO %s
+
+// LARGE: warning: using '-ze-opt-large-register-file' to set GRF mode on PVC hardware is deprecated; use '-ftarget-register-alloc-mode=pvc:large'
+// SMALL: warning: using '-ze-intel-128-GRF-per-thread' to set GRF mode on PVC hardware is deprecated; use '-ftarget-register-alloc-mode=pvc:small'
+// AUTO:  warning: using '-ze-intel-enable-auto-large-GRF-mode' to set GRF mode on PVC hardware is deprecated; use '-ftarget-register-alloc-mode=pvc:auto'