r317605 - New clang option -fno-plt which avoids the PLT and lazy binding while making external calls.
Sriraman Tallam via cfe-commits
cfe-commits at lists.llvm.org
Tue Nov 7 11:37:52 PST 2017
Author: tmsriram
Date: Tue Nov 7 11:37:51 2017
New Revision: 317605
URL: http://llvm.org/viewvc/llvm-project?rev=317605&view=rev
Log:
New clang option -fno-plt which avoids the PLT and lazy binding while making external calls.
Differential Revision: https://reviews.llvm.org/D39079
Added:
cfe/trunk/test/CodeGen/noplt.c
Modified:
cfe/trunk/include/clang/Driver/Options.td
cfe/trunk/include/clang/Frontend/CodeGenOptions.def
cfe/trunk/lib/CodeGen/CGCall.cpp
cfe/trunk/lib/Driver/ToolChains/Clang.cpp
cfe/trunk/lib/Frontend/CompilerInvocation.cpp
Modified: cfe/trunk/include/clang/Driver/Options.td
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Driver/Options.td?rev=317605&r1=317604&r2=317605&view=diff
==============================================================================
--- cfe/trunk/include/clang/Driver/Options.td (original)
+++ cfe/trunk/include/clang/Driver/Options.td Tue Nov 7 11:37:51 2017
@@ -1384,6 +1384,10 @@ def fpic : Flag<["-"], "fpic">, Group<f_
def fno_pic : Flag<["-"], "fno-pic">, Group<f_Group>;
def fpie : Flag<["-"], "fpie">, Group<f_Group>;
def fno_pie : Flag<["-"], "fno-pie">, Group<f_Group>;
+def fplt : Flag<["-"], "fplt">, Group<f_Group>, Flags<[CC1Option]>,
+ HelpText<"Use the PLT to make function calls">;
+def fno_plt : Flag<["-"], "fno-plt">, Group<f_Group>, Flags<[CC1Option]>,
+ HelpText<"Do not use the PLT to make function calls">;
def fropi : Flag<["-"], "fropi">, Group<f_Group>;
def fno_ropi : Flag<["-"], "fno-ropi">, Group<f_Group>;
def frwpi : Flag<["-"], "frwpi">, Group<f_Group>;
Modified: cfe/trunk/include/clang/Frontend/CodeGenOptions.def
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Frontend/CodeGenOptions.def?rev=317605&r1=317604&r2=317605&view=diff
==============================================================================
--- cfe/trunk/include/clang/Frontend/CodeGenOptions.def (original)
+++ cfe/trunk/include/clang/Frontend/CodeGenOptions.def Tue Nov 7 11:37:51 2017
@@ -297,6 +297,8 @@ CODEGENOPT(PreserveVec3Type, 1, 0)
/// Whether to emit .debug_gnu_pubnames section instead of .debug_pubnames.
CODEGENOPT(GnuPubnames, 1, 0)
+CODEGENOPT(NoPLT, 1, 0)
+
#undef CODEGENOPT
#undef ENUM_CODEGENOPT
#undef VALUE_CODEGENOPT
Modified: cfe/trunk/lib/CodeGen/CGCall.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGCall.cpp?rev=317605&r1=317604&r2=317605&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGCall.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGCall.cpp Tue Nov 7 11:37:51 2017
@@ -1855,6 +1855,16 @@ void CodeGenModule::ConstructAttributeLi
!(TargetDecl && TargetDecl->hasAttr<NoSplitStackAttr>()))
FuncAttrs.addAttribute("split-stack");
+ // Add NonLazyBind attribute to function declarations when -fno-plt
+ // is used.
+ if (TargetDecl && CodeGenOpts.NoPLT) {
+ if (auto *Fn = dyn_cast<FunctionDecl>(TargetDecl)) {
+ if (!Fn->isDefined() && !AttrOnCallSite) {
+ FuncAttrs.addAttribute(llvm::Attribute::NonLazyBind);
+ }
+ }
+ }
+
if (!AttrOnCallSite) {
bool DisableTailCalls =
CodeGenOpts.DisableTailCalls ||
Modified: cfe/trunk/lib/Driver/ToolChains/Clang.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains/Clang.cpp?rev=317605&r1=317604&r2=317605&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/ToolChains/Clang.cpp (original)
+++ cfe/trunk/lib/Driver/ToolChains/Clang.cpp Tue Nov 7 11:37:51 2017
@@ -3423,6 +3423,10 @@ void Clang::ConstructJob(Compilation &C,
CmdArgs.push_back("-mpie-copy-relocations");
}
+ if (Args.hasFlag(options::OPT_fno_plt, options::OPT_fplt, false)) {
+ CmdArgs.push_back("-fno-plt");
+ }
+
// -fhosted is default.
// TODO: Audit uses of KernelOrKext and see where it'd be more appropriate to
// use Freestanding.
Modified: cfe/trunk/lib/Frontend/CompilerInvocation.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/CompilerInvocation.cpp?rev=317605&r1=317604&r2=317605&view=diff
==============================================================================
--- cfe/trunk/lib/Frontend/CompilerInvocation.cpp (original)
+++ cfe/trunk/lib/Frontend/CompilerInvocation.cpp Tue Nov 7 11:37:51 2017
@@ -653,6 +653,7 @@ static bool ParseCodeGenArgs(CodeGenOpti
Args.hasArg(OPT_mincremental_linker_compatible);
Opts.PIECopyRelocations =
Args.hasArg(OPT_mpie_copy_relocations);
+ Opts.NoPLT = Args.hasArg(OPT_fno_plt);
Opts.OmitLeafFramePointer = Args.hasArg(OPT_momit_leaf_frame_pointer);
Opts.SaveTempLabels = Args.hasArg(OPT_msave_temp_labels);
Opts.NoDwarfDirectoryAsm = Args.hasArg(OPT_fno_dwarf_directory_asm);
Added: cfe/trunk/test/CodeGen/noplt.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/noplt.c?rev=317605&view=auto
==============================================================================
--- cfe/trunk/test/CodeGen/noplt.c (added)
+++ cfe/trunk/test/CodeGen/noplt.c Tue Nov 7 11:37:51 2017
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -emit-llvm -fno-plt %s -o - | FileCheck %s -check-prefix=CHECK-NOPLT
+
+// CHECK-NOPLT: Function Attrs: nonlazybind
+// CHECK-NOPLT-NEXT: declare i32 @foo
+int foo();
+
+int bar() {
+ return foo();
+}
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