[ThinLTO][Matrix] Forward -enable-matrix flag to the LTO plugin

[w2yehia]

Summary

Forward -enable-matrix flag to the LTO plugin because matrix intrinsics lowering happens at link time in thinLTO.

[w2yehia]

this was caught when I tried running test-suite with -flto=thin

[w2yehia]

forgot to touch dummy input file.

[MaskRay]

clang/test/Driver/clang_f_opts.c

615 ↗

(On Diff #534557)

Don't use clang_f_opts.c. Pick a more a specific aix-* test file.

[w2yehia]

clang/test/Driver/clang_f_opts.c

615 ↗

(On Diff #534557)

Thanks @MaskRay
this is a general change, not specific to AIX. I'm just testing the two plugin-opt/bplugin_opt spellings. Or do you mean to move the AIX specific test to aix-* and keep the generic (I picked x86_64-unknown-linux) one here?

[w2yehia]

@fhahn ping. Thanks

clang/test/Driver/clang_f_opts.c

615 ↗

(On Diff #534557)

@MaskRay ping. Thanks

[w2yehia]

@MaskRay @fhahn ping. Thanks

[MaskRay]

clang/test/Driver/clang_f_opts.c

615 ↗

(On Diff #534557)

My thought stays the same. We probably should find another test file for enable-matrix.

[w2yehia]

move tests into its own file

[w2yehia]

@fhahn can you please review when you have a chance. Thanks

[MaskRay]

clang/lib/Driver/ToolChains/CommonArgs.cpp

683

With regular LTO, when does it happen?

The canonical spelling for ThinLTO is "ThinLTO".

clang/test/Driver/matrix.c

8

We normally add double quotes for tested options.

[w2yehia]

clang/lib/Driver/ToolChains/CommonArgs.cpp

683

The lowering pass is added in buildModuleOptimizationPipeline function:

if (EnableMatrix) {
  OptimizePM.addPass(LowerMatrixIntrinsicsPass());
  OptimizePM.addPass(EarlyCSEPass());
}

Here's the PassBuilder pipelines for thin and full LTO:

thinLTO compile
  buildThinLTOPreLinkDefaultPipeline
thinLTO link:
  buildThinLTODefaultPipeline
    buildModuleOptimizationPipeline

fullLTO compile:
  buildLTOPreLinkDefaultPipeline
    buildPerModuleDefaultPipeline
      buildModuleOptimizationPipeline
fullLTO link:
  buildLTODefaultPipeline

[w2yehia]

address MaskRay's comments

[w2yehia]

@MaskRay @fhahn please review when you have time. Thanks

[w2yehia]

clang-format

[w2yehia]

@fhahn @MaskRay ping. Thanks.

[MaskRay]

clang/lib/Driver/ToolChains/CommonArgs.cpp

683

I see. The comment seems unclear.

// Enable matrix intrinsic lowering (LowerMatrixIntrinsicsPass), which is transitively called by buildThinLTODefaultPipeline.

clang/test/Driver/matrix.c

6

Replace ^//$ with an empty line

[MaskRay]

clang/lib/Driver/ToolChains/CommonArgs.cpp

683

// Matrix intrinsic lowering happens at link time with ThinLTO. Enable LowerMatrixIntrinsicsPass, which is transitively called by buildThinLTODefaultPipeline under EnableMatrix.

clang/lib/Driver/ToolChains/CommonArgs.cpp

if (Args.hasArg(options::OPT_gsplit_dwarf))
     CmdArgs.push_back(Args.MakeArgString(
         Twine(PluginOptPrefix) + "dwo_dir=" + Output.getFilename() + "_dwo"));
 
   if (IsThinLTO && !IsOSAIX)
     CmdArgs.push_back(Args.MakeArgString(Twine(PluginOptPrefix) + "thinlto"));
   else if (IsThinLTO && IsOSAIX)
     CmdArgs.push_back(Args.MakeArgString(Twine("-bdbg:thinlto")));
 
+  // Matrix intrinsic lowering happens at link time with ThinLTO. Enable
+  // LowerMatrixIntrinsicsPass, which is transitively called by
+  // buildThinLTODefaultPipeline under EnableMatrix.
+  if (IsThinLTO && Args.hasArg(options::OPT_fenable_matrix))
+    CmdArgs.push_back(
+        Args.MakeArgString(Twine(PluginOptPrefix) + "-enable-matrix"));
 
   StringRef Parallelism = getLTOParallelism(Args, D);
   if (!Parallelism.empty())
     CmdArgs.push_back(
         Args.MakeArgString(Twine(PluginOptPrefix) + "jobs=" + Parallelism));
 
   // If an explicit debugger tuning argument appeared, pass it along.
   if (Arg *A =

clang/test/Driver/matrix.c

+// RUN: touch %t.o
+// RUN: %clang -flto=thin -fenable-matrix %t.o -### --target=powerpc64-ibm-aix-xcoff 2>&1 \
+// RUN:     | FileCheck %s -check-prefix=CHECK-THINLTO-MATRIX-AIX
+// CHECK-THINLTO-MATRIX-AIX: "-bplugin_opt:-enable-matrix"
+
+// RUN: %clang -flto=thin -fenable-matrix %t.o -### --target=x86_64-unknown-linux 2>&1 \
+// RUN:     | FileCheck %s -check-prefix=CHECK-THINLTO-MATRIX
+// CHECK-THINLTO-MATRIX: "-plugin-opt=-enable-matrix"