[clang] [LTO] Fix Veclib flags correctly pass to LTO flags (PR #78749)

[Paschalis Mpeis via cfe-commits]

https://github.com/paschalis-mpeis created https://github.com/llvm/llvm-project/pull/78749

Flags `-fveclib=name` were not passed to LTO flags.
This pass fixes that by converting the `-fveclib` flags to their relevant names for opt's `-vector-lib=name` flags.

For example:
`-fveclib=SLEEF` would become `-vector-library=sleefgnuabi` and passed through the `-plugin-opt` flag.

>From e1f97413fc7cf42a4b47b27b6ec6d377ea8113b1 Mon Sep 17 00:00:00 2001
From: Paschalis Mpeis <Paschalis.Mpeis at arm.com>
Date: Fri, 19 Jan 2024 16:27:20 +0000
Subject: [PATCH] [LTO] Fix Veclib flags correctly pass to LTO flags

Flags `-fveclib=name` were not passed to LTO flags.
This pass fixes that by converting the `-fveclib` flags to their
relevant names for opt's `-vector-lib=name` flags.

For example:
`-fveclib=SLEEF` would become `-vector-library=sleefgnuabi` and passed
through the -plugin-opt` flag.
---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 22 +++++++++++++++++
 clang/test/Driver/fveclib.c                | 28 ++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 385f66f3782bc1..470145849e4187 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -783,6 +783,28 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
                                          "-generate-arange-section"));
   }
 
+  // Pass vector library arguments to LTO.
+  Arg *ArgVecLib = Args.getLastArg(options::OPT_fveclib);
+  if (ArgVecLib && ArgVecLib->getNumValues() == 1) {
+    // Map the vector library names from clang front-end to opt front-end. The
+    // values are taken from the TargetLibraryInfo class command line options.
+    std::optional<StringRef> OptVal =
+        llvm::StringSwitch<std::optional<StringRef>>(ArgVecLib->getValue())
+            .Case("Accelerate", "Accelerate")
+            .Case("LIBMVEC", "LIBMVEC-X86")
+            .Case("MASSV", "MASSV")
+            .Case("SVML", "SVML")
+            .Case("SLEEF", "sleefgnuabi")
+            .Case("Darwin_libsystem_m", "Darwin_libsystem_m")
+            .Case("ArmPL", "ArmPL")
+            .Case("none", "none")
+            .Default(std::nullopt);
+
+    if (OptVal)
+      CmdArgs.push_back(Args.MakeArgString(
+          Twine(PluginOptPrefix) + "-vector-library=" + OptVal.value()));
+  }
+
   // Try to pass driver level flags relevant to LTO code generation down to
   // the plugin.
 
diff --git a/clang/test/Driver/fveclib.c b/clang/test/Driver/fveclib.c
index e2a7619e9b89f7..8ce7bcbb67ae0b 100644
--- a/clang/test/Driver/fveclib.c
+++ b/clang/test/Driver/fveclib.c
@@ -31,3 +31,31 @@
 
 // RUN: %clang -fveclib=Accelerate %s -nodefaultlibs -target arm64-apple-ios8.0.0 -### 2>&1 | FileCheck --check-prefix=CHECK-LINK-NODEFAULTLIBS %s
 // CHECK-LINK-NODEFAULTLIBS-NOT: "-framework" "Accelerate"
+
+
+/* Verify that the correct vector library is passed to LTO flags. */
+
+
+// RUN: %clang -### -fveclib=none -flto %s -v 2>&1  | FileCheck -check-prefix CHECK-LTO-NOLIB %s
+// CHECK-LTO-NOLIB: "-plugin-opt=-vector-library=none"
+
+// RUN: %clang -### -fveclib=Accelerate -flto %s -v 2>&1  | FileCheck -check-prefix CHECK-LTO-ACCELERATE %s
+// CHECK-LTO-ACCELERATE: "-plugin-opt=-vector-library=Accelerate"
+
+// RUN: %clang -### -fveclib=LIBMVEC -flto %s -v 2>&1  | FileCheck -check-prefix CHECK-LTO-LIBMVEC %s
+// CHECK-LTO-LIBMVEC: "-plugin-opt=-vector-library=LIBMVEC-X86"
+
+// RUN: %clang -### -fveclib=MASSV -flto %s -v 2>&1  | FileCheck -check-prefix CHECK-LTO-MASSV %s
+// CHECK-LTO-MASSV: "-plugin-opt=-vector-library=MASSV"
+
+// RUN: not %clang -### -fveclib=SVML -flto %s -v 2>&1  | FileCheck -check-prefix CHECK-LTO-SVML %s
+// CHECK-LTO-SVML: "-plugin-opt=-vector-library=SVML"
+
+// RUN: %clang -### -fveclib=SLEEF -flto %s -v 2>&1  | FileCheck -check-prefix CHECK-LTO-SLEEF %s
+// CHECK-LTO-SLEEF: "-plugin-opt=-vector-library=sleefgnuabi"
+
+// RUN: %clang -### -fveclib=Darwin_libsystem_m -flto %s -v 2>&1  | FileCheck -check-prefix CHECK-LTO-DARWIN %s
+// CHECK-LTO-DARWIN: "-plugin-opt=-vector-library=Darwin_libsystem_m"
+
+// RUN: %clang -### -fveclib=ArmPL -flto %s -v 2>&1  | FileCheck -check-prefix CHECK-LTO-ARMPL %s
+// CHECK-LTO-ARMPL: "-plugin-opt=-vector-library=ArmPL"