[Driver][X86] Support branch align options with LTO

Summary: Before this patch, we use two different ways to pass options to align branch
depending on whether LTO is enabled. For example, `-mbranches-within-32B-boundaries`
w/o LTO and `-Wl,-plugin-opt=-x86-branches-within-32B-boundaries` w/ LTO.  It's
inconvenient, so this patch unifies the way: we only need to pass options like
`-mbranches-within-32B-boundaries` to align branches, no matter LTO is enabled or not.

Differential Revision: https://reviews.llvm.org/D80289

clang/lib/Driver/ToolChains/Clang.cpp

@@ -2045,57 +2045,10 @@ void Clang::AddSystemZTargetArgs(const ArgList &Args,
   }
 }
 
-static void addX86AlignBranchArgs(const Driver &D, const ArgList &Args,
-                                  ArgStringList &CmdArgs) {
-  if (Args.hasArg(options::OPT_mbranches_within_32B_boundaries)) {
-    CmdArgs.push_back("-mllvm");
-    CmdArgs.push_back("-x86-branches-within-32B-boundaries");
-  }
-  if (const Arg *A = Args.getLastArg(options::OPT_malign_branch_boundary_EQ)) {
-    StringRef Value = A->getValue();
-    unsigned Boundary;
-    if (Value.getAsInteger(10, Boundary) || Boundary < 16 ||
-        !llvm::isPowerOf2_64(Boundary)) {
-      D.Diag(diag::err_drv_invalid_argument_to_option)
-          << Value << A->getOption().getName();
-    } else {
-      CmdArgs.push_back("-mllvm");
-      CmdArgs.push_back(
-          Args.MakeArgString("-x86-align-branch-boundary=" + Twine(Boundary)));
-    }
-  }
-  if (const Arg *A = Args.getLastArg(options::OPT_malign_branch_EQ)) {
-    std::string AlignBranch;
-    for (StringRef T : A->getValues()) {
-      if (T != "fused" && T != "jcc" && T != "jmp" && T != "call" &&
-          T != "ret" && T != "indirect")
-        D.Diag(diag::err_drv_invalid_malign_branch_EQ)
-            << T << "fused, jcc, jmp, call, ret, indirect";
-      if (!AlignBranch.empty())
-        AlignBranch += '+';
-      AlignBranch += T;
-    }
-    CmdArgs.push_back("-mllvm");
-    CmdArgs.push_back(Args.MakeArgString("-x86-align-branch=" + AlignBranch));
-  }
-  if (const Arg *A = Args.getLastArg(options::OPT_mpad_max_prefix_size_EQ)) {
-    StringRef Value = A->getValue();
-    unsigned PrefixSize;
-    if (Value.getAsInteger(10, PrefixSize)) {
-      D.Diag(diag::err_drv_invalid_argument_to_option)
-          << Value << A->getOption().getName();
-    } else {
-      CmdArgs.push_back("-mllvm");
-      CmdArgs.push_back(
-          Args.MakeArgString("-x86-pad-max-prefix-size=" + Twine(PrefixSize)));
-    }
-  }
-}
-
 void Clang::AddX86TargetArgs(const ArgList &Args,
                              ArgStringList &CmdArgs) const {
   const Driver &D = getToolChain().getDriver();
-  addX86AlignBranchArgs(D, Args, CmdArgs);
+  addX86AlignBranchArgs(D, Args, CmdArgs, /*IsLTO=*/false);
 
   if (!Args.hasFlag(options::OPT_mred_zone, options::OPT_mno_red_zone, true) ||
       Args.hasArg(options::OPT_mkernel) ||
@@ -6745,7 +6698,8 @@ void ClangAs::AddMIPSTargetArgs(const ArgList &Args,
 
 void ClangAs::AddX86TargetArgs(const ArgList &Args,
                                ArgStringList &CmdArgs) const {
-  addX86AlignBranchArgs(getToolChain().getDriver(), Args, CmdArgs);
+  addX86AlignBranchArgs(getToolChain().getDriver(), Args, CmdArgs,
+                        /*IsLTO=*/false);
 
   if (Arg *A = Args.getLastArg(options::OPT_masm_EQ)) {
     StringRef Value = A->getValue();

clang/lib/Driver/ToolChains/CommonArgs.cpp

@@ -358,6 +358,7 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
                           ArgStringList &CmdArgs, const InputInfo &Output,
                           const InputInfo &Input, bool IsThinLTO) {
   const char *Linker = Args.MakeArgString(ToolChain.GetLinkerPath());
+  const Driver &D = ToolChain.getDriver();
   if (llvm::sys::path::filename(Linker) != "ld.lld" &&
       llvm::sys::path::stem(Linker) != "ld.lld") {
     // Tell the linker to load the plugin. This has to come before
@@ -374,10 +375,9 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
 #endif
 
     SmallString<1024> Plugin;
-    llvm::sys::path::native(Twine(ToolChain.getDriver().Dir) +
-                                "/../lib" CLANG_LIBDIR_SUFFIX "/LLVMgold" +
-                                Suffix,
-                            Plugin);
+    llvm::sys::path::native(
+        Twine(D.Dir) + "/../lib" CLANG_LIBDIR_SUFFIX "/LLVMgold" + Suffix,
+        Plugin);
     CmdArgs.push_back(Args.MakeArgString(Plugin));
   }
 
@@ -417,7 +417,7 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
   if (IsThinLTO)
     CmdArgs.push_back("-plugin-opt=thinlto");
 
-  StringRef Parallelism = getLTOParallelism(Args, ToolChain.getDriver());
+  StringRef Parallelism = getLTOParallelism(Args, D);
   if (!Parallelism.empty())
     CmdArgs.push_back(
         Args.MakeArgString("-plugin-opt=jobs=" + Twine(Parallelism)));
@@ -449,7 +449,7 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
   if (Arg *A = getLastProfileSampleUseArg(Args)) {
     StringRef FName = A->getValue();
     if (!llvm::sys::fs::exists(FName))
-      ToolChain.getDriver().Diag(diag::err_drv_no_such_file) << FName;
+      D.Diag(diag::err_drv_no_such_file) << FName;
     else
       CmdArgs.push_back(
           Args.MakeArgString(Twine("-plugin-opt=sample-profile=") + FName));
@@ -492,11 +492,12 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
   }
 
   // Setup statistics file output.
-  SmallString<128> StatsFile =
-      getStatsFileName(Args, Output, Input, ToolChain.getDriver());
+  SmallString<128> StatsFile = getStatsFileName(Args, Output, Input, D);
   if (!StatsFile.empty())
     CmdArgs.push_back(
         Args.MakeArgString(Twine("-plugin-opt=stats-file=") + StatsFile));
+
+  addX86AlignBranchArgs(D, Args, CmdArgs, /*IsLTO=*/true);
 }
 
 void tools::addArchSpecificRPath(const ToolChain &TC, const ArgList &Args,
@@ -1423,3 +1424,53 @@ void tools::addMultilibFlag(bool Enabled, const char *const Flag,
                             Multilib::flags_list &Flags) {
   Flags.push_back(std::string(Enabled ? "+" : "-") + Flag);
 }
+
+void tools::addX86AlignBranchArgs(const Driver &D, const ArgList &Args,
+                                  ArgStringList &CmdArgs, bool IsLTO) {
+  auto addArg = [&, IsLTO](const Twine &Arg) {
+    if (IsLTO) {
+      CmdArgs.push_back(Args.MakeArgString("-plugin-opt=" + Arg));
+    } else {
+      CmdArgs.push_back("-mllvm");
+      CmdArgs.push_back(Args.MakeArgString(Arg));
+    }
+  };
+
+  if (Args.hasArg(options::OPT_mbranches_within_32B_boundaries)) {
+    addArg(Twine("-x86-branches-within-32B-boundaries"));
+  }
+  if (const Arg *A = Args.getLastArg(options::OPT_malign_branch_boundary_EQ)) {
+    StringRef Value = A->getValue();
+    unsigned Boundary;
+    if (Value.getAsInteger(10, Boundary) || Boundary < 16 ||
+        !llvm::isPowerOf2_64(Boundary)) {
+      D.Diag(diag::err_drv_invalid_argument_to_option)
+          << Value << A->getOption().getName();
+    } else {
+      addArg("-x86-align-branch-boundary=" + Twine(Boundary));
+    }
+  }
+  if (const Arg *A = Args.getLastArg(options::OPT_malign_branch_EQ)) {
+    std::string AlignBranch;
+    for (StringRef T : A->getValues()) {
+      if (T != "fused" && T != "jcc" && T != "jmp" && T != "call" &&
+          T != "ret" && T != "indirect")
+        D.Diag(diag::err_drv_invalid_malign_branch_EQ)
+            << T << "fused, jcc, jmp, call, ret, indirect";
+      if (!AlignBranch.empty())
+        AlignBranch += '+';
+      AlignBranch += T;
+    }
+    addArg("-x86-align-branch=" + Twine(AlignBranch));
+  }
+  if (const Arg *A = Args.getLastArg(options::OPT_mpad_max_prefix_size_EQ)) {
+    StringRef Value = A->getValue();
+    unsigned PrefixSize;
+    if (Value.getAsInteger(10, PrefixSize)) {
+      D.Diag(diag::err_drv_invalid_argument_to_option)
+          << Value << A->getOption().getName();
+    } else {
+      addArg("-x86-pad-max-prefix-size=" + Twine(PrefixSize));
+    }
+  }
+}

clang/lib/Driver/ToolChains/CommonArgs.h

@@ -127,6 +127,8 @@ SmallString<128> getStatsFileName(const llvm::opt::ArgList &Args,
 void addMultilibFlag(bool Enabled, const char *const Flag,
                      Multilib::flags_list &Flags);
 
+void addX86AlignBranchArgs(const Driver &D, const llvm::opt::ArgList &Args,
+                           llvm::opt::ArgStringList &CmdArgs, bool IsLTO);
 } // end namespace tools
 } // end namespace driver
 } // end namespace clang

clang/test/Driver/x86-malign-branch.c

@@ -1,8 +1,10 @@
-/// Test that -malign-branch* and -mbranches-within-32B-boundaries are parsed and converted to -mllvm options.
+/// Test that -malign-branch* and -mbranches-within-32B-boundaries are parsed and converted to MC options.
 
 /// Test -malign-branch-boundary=
 // RUN: %clang -target x86_64 -malign-branch-boundary=16 %s -c -### 2>&1 | FileCheck %s --check-prefix=BOUNDARY
 // BOUNDARY: "-mllvm" "-x86-align-branch-boundary=16"
+// RUN: %clang -target x86_64-unknown-linux -malign-branch-boundary=16 -flto %s -### 2>&1 | FileCheck %s --check-prefix=BOUNDARY-LTO
+// BOUNDARY-LTO: "-plugin-opt=-x86-align-branch-boundary=16"
 
 // RUN: %clang -target x86_64 -malign-branch-boundary=8 %s -c -### 2>&1 | FileCheck %s --check-prefix=BOUNDARY-ERR
 // RUN: %clang -target x86_64 -malign-branch-boundary=15 %s -c -### 2>&1 | FileCheck %s --check-prefix=BOUNDARY-ERR
@@ -13,6 +15,8 @@
 // TYPE0: "-mllvm" "-x86-align-branch=fused+jcc+jmp"
 // RUN: %clang -target x86_64 -malign-branch=fused,jcc,jmp,ret,call,indirect %s -c -### %s 2>&1 | FileCheck %s --check-prefix=TYPE1
 // TYPE1: "-mllvm" "-x86-align-branch=fused+jcc+jmp+ret+call+indirect"
+// RUN: %clang -target x86_64-unknown-linux -malign-branch=fused,jcc,jmp -flto %s -### %s 2>&1 | FileCheck %s --check-prefix=TYPE0-LTO
+// TYPE0-LTO: "-plugin-opt=-x86-align-branch=fused+jcc+jmp"
 
 // RUN: %clang -target x86_64 -malign-branch=fused,foo,bar %s -c -### %s 2>&1 | FileCheck %s --check-prefix=TYPE-ERR
 // TYPE-ERR: invalid argument 'foo' to -malign-branch=; each element must be one of: fused, jcc, jmp, call, ret, indirect
@@ -23,10 +27,14 @@
 // PREFIX-0: "-mllvm" "-x86-pad-max-prefix-size=0"
 // RUN: %clang -target x86_64 -mpad-max-prefix-size=15 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX-15
 // PREFIX-15: "-mllvm" "-x86-pad-max-prefix-size=15"
+// RUN: %clang -target x86_64-unknown-linux -mpad-max-prefix-size=0 -flto %s -### 2>&1 | FileCheck %s --check-prefix=PREFIX-0-LTO
+// PREFIX-0-LTO: "-plugin-opt=-x86-pad-max-prefix-size=0"
 
 /// Test -mbranches-within-32B-boundaries
 // RUN: %clang -target x86_64 -mbranches-within-32B-boundaries %s -c -### 2>&1 | FileCheck %s --check-prefix=32B
 // 32B: "-mllvm" "-x86-branches-within-32B-boundaries"
+// RUN: %clang -target x86_64-unknown-linux -mbranches-within-32B-boundaries -flto %s -### 2>&1 | FileCheck %s --check-prefix=32B-LTO
+// 32B-LTO: "-plugin-opt=-x86-branches-within-32B-boundaries"
 
 /// Unsupported on other targets.
 // RUN: %clang -target aarch64 -malign-branch=jmp %s -c -### 2>&1 | FileCheck --check-prefix=UNUSED %s