[clang] [Clang][LTO][GISel] Propagate `-fglobal-siel` to LTO (PR #69747)

[Min-Yih Hsu via cfe-commits]

https://github.com/mshockwave updated https://github.com/llvm/llvm-project/pull/69747

>From 8abc9204d4148f1b224623ac54d5f58e2ab04e6b Mon Sep 17 00:00:00 2001
From: Min-Yih Hsu <min.hsu at sifive.com>
Date: Fri, 20 Oct 2023 11:03:30 -0700
Subject: [PATCH 1/2] [Clang][LTO][GISel] Propagate `-fglobal-siel` to LTO

Translate `-fglobal-isel` to `-plugin-opt=-global-isel=1`.
---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 10 ++++++++++
 clang/test/Driver/lto.c                    |  9 +++++++++
 2 files changed, 19 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 7b2966f70bf6fc6..923fac940a00d3c 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -694,6 +694,16 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
     CmdArgs.push_back(Args.MakeArgString(Twine(PluginOptPrefix) +
                                          ParallelismOpt + Parallelism));
 
+  // Pass down GlobalISel options.
+  if (Arg *A = Args.getLastArg(options::OPT_fglobal_isel,
+                               options::OPT_fno_global_isel)) {
+    // Parsing -fno-global-isel explicitly gives architectures that enable GISel
+    // by default (e.g. AArch64) a chance to disable it.
+    CmdArgs.push_back(Args.MakeArgString(
+        Twine(PluginOptPrefix) + "-global-isel=" +
+        (A->getOption().matches(options::OPT_fglobal_isel) ? "1" : "0")));
+  }
+
   // If an explicit debugger tuning argument appeared, pass it along.
   if (Arg *A =
           Args.getLastArg(options::OPT_gTune_Group, options::OPT_ggdbN_Group)) {
diff --git a/clang/test/Driver/lto.c b/clang/test/Driver/lto.c
index 62bdbd6f5d3cfa3..b6c89eb99e27419 100644
--- a/clang/test/Driver/lto.c
+++ b/clang/test/Driver/lto.c
@@ -105,3 +105,12 @@
 // FLTO-THIN: -flto=thin
 // FLTO-THIN-NOT: "-flto"
 // FLTO-THIN-NOT: -flto=full
+
+// -flto passes along an explicit GlobalISel flag.
+// RUN: %clang --target=riscv64-linux-gnu -### %s -flto -fglobal-isel 2> %t
+// RUN: FileCheck --check-prefix=CHECK-GISEL < %t %s
+// RUN: %clang --target=aarch64-linux-gnu -### %s -flto -fno-global-isel 2> %t
+// RUN: FileCheck --check-prefix=CHECK-DISABLE-GISEL < %t %s
+//
+// CHECK-GISEL:         "-plugin-opt=-global-isel=1"
+// CHECK-DISABLE-GISEL: "-plugin-opt=-global-isel=0"

>From 2c4a02e9536446281901233756b9493d3e01f64f Mon Sep 17 00:00:00 2001
From: Min-Yih Hsu <min.hsu at sifive.com>
Date: Tue, 24 Oct 2023 09:11:43 -0700
Subject: [PATCH 2/2] fixup! [Clang][LTO][GISel] Propagate `-fglobal-siel` to
 LTO

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 923fac940a00d3c..6ea89d7726db2d0 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -698,7 +698,7 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
   if (Arg *A = Args.getLastArg(options::OPT_fglobal_isel,
                                options::OPT_fno_global_isel)) {
     // Parsing -fno-global-isel explicitly gives architectures that enable GISel
-    // by default (e.g. AArch64) a chance to disable it.
+    // by default a chance to disable it.
     CmdArgs.push_back(Args.MakeArgString(
         Twine(PluginOptPrefix) + "-global-isel=" +
         (A->getOption().matches(options::OPT_fglobal_isel) ? "1" : "0")));