This revision was automatically updated to reflect the committed changes.
Closed by commit rC337333: Teach Clang to emit address-significance tables.
(authored by pcc, committed by ).
Changed prior to commit:
https://reviews.llvm.org/D48155?vs=151282&id=155984#toc
Repository:
rC Clang
https://reviews.llvm.org/D48155
Files:
docs/ReleaseNotes.rst
docs/UsersManual.rst
include/clang/Driver/Options.td
include/clang/Frontend/CodeGenOptions.def
lib/CodeGen/BackendUtil.cpp
lib/Driver/ToolChains/Clang.cpp
lib/Frontend/CompilerInvocation.cpp
test/CodeGen/addrsig.c
test/Driver/addrsig.c
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -4777,6 +4777,11 @@
}
}
+ if (Args.hasFlag(options::OPT_faddrsig, options::OPT_fno_addrsig,
+ getToolChain().getTriple().isOSBinFormatELF() &&
+ getToolChain().useIntegratedAs()))
+ CmdArgs.push_back("-faddrsig");
+
// Finally add the compile command to the compilation.
if (Args.hasArg(options::OPT__SLASH_fallback) &&
Output.getType() == types::TY_Object &&
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -1119,6 +1119,8 @@
Opts.EmitVersionIdentMetadata = Args.hasFlag(OPT_Qy, OPT_Qn, true);
+ Opts.Addrsig = Args.hasArg(OPT_faddrsig);
+
return Success;
}
Index: lib/CodeGen/BackendUtil.cpp
===================================================================
--- lib/CodeGen/BackendUtil.cpp
+++ lib/CodeGen/BackendUtil.cpp
@@ -454,6 +454,7 @@
Options.ExplicitEmulatedTLS = CodeGenOpts.ExplicitEmulatedTLS;
Options.DebuggerTuning = CodeGenOpts.getDebuggerTuning();
Options.EmitStackSizeSection = CodeGenOpts.StackSizeSection;
+ Options.EmitAddrsig = CodeGenOpts.Addrsig;
if (CodeGenOpts.EnableSplitDwarf)
Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -98,6 +98,14 @@
finding out the warning hierarchy, and which of them are enabled by default
or for a particular compiler invocation.
+- By default, Clang emits an address-significance table into
+ every ELF object file when using the integrated assembler.
+ Address-significance tables allow linkers to implement `safe ICF
+ <https://research.google.com/pubs/archive/36912.pdf>`_ without the false
+ positives that can result from other implementation techniques such as
+ relocation scanning. The ``-faddrsig`` and ``-fno-addrsig`` flags can be
+ used to control whether to emit the address-significance table.
+
- ...
New Compiler Flags
Index: docs/UsersManual.rst
===================================================================
--- docs/UsersManual.rst
+++ docs/UsersManual.rst
@@ -1382,6 +1382,15 @@
// value of -fmax-type-align.
}
+.. option:: -faddrsig, -fno-addrsig
+
+ Controls whether Clang emits an address-significance table into the object
+ file. Address-significance tables allow linkers to implement `safe ICF
+ <https://research.google.com/pubs/archive/36912.pdf>`_ without the false
+ positives that can result from other implementation techniques such as
+ relocation scanning. Address-significance tables are enabled by default
+ on ELF targets when using the integrated assembler. This flag currently
+ only has an effect on ELF targets.
Profile Guided Optimization
---------------------------
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -758,6 +758,10 @@
def fno_profile_use : Flag<["-"], "fno-profile-use">,
Alias<fno_profile_instr_use>;
+def faddrsig : Flag<["-"], "faddrsig">, Group<f_Group>, Flags<[CoreOption, CC1Option]>,
+ HelpText<"Emit an address-significance table">;
+def fno_addrsig : Flag<["-"], "fno-addrsig">, Group<f_Group>, Flags<[CoreOption]>,
+ HelpText<"Don't emit an address-significance table">;
def fblocks : Flag<["-"], "fblocks">, Group<f_Group>, Flags<[CC1Option]>,
HelpText<"Enable the 'blocks' language feature">;
def fbootclasspath_EQ : Joined<["-"], "fbootclasspath=">, Group<f_Group>;
Index: include/clang/Frontend/CodeGenOptions.def
===================================================================
--- include/clang/Frontend/CodeGenOptions.def
+++ include/clang/Frontend/CodeGenOptions.def
@@ -335,6 +335,9 @@
/// Whether to emit all vtables
CODEGENOPT(ForceEmitVTables, 1, 0)
+/// Whether to emit an address-significance table into the object file.
+CODEGENOPT(Addrsig, 1, 0)
+
#undef CODEGENOPT
#undef ENUM_CODEGENOPT
Index: test/CodeGen/addrsig.c
===================================================================
--- test/CodeGen/addrsig.c
+++ test/CodeGen/addrsig.c
@@ -0,0 +1,18 @@
+// RUN: %clang_cc1 -triple=x86_64-unknown-linux -S %s -faddrsig -O -o - | FileCheck --check-prefix=ADDRSIG %s
+// RUN: %clang_cc1 -triple=x86_64-unknown-linux -S %s -O -o - | FileCheck --check-prefix=NO-ADDRSIG %s
+
+// ADDRSIG: .addrsig
+// ADDRSIG: .addrsig_sym g1
+// ADDRSIG-NOT: .addrsig_sym g2
+
+// NO-ADDRSIG-NOT: .addrsig
+
+extern const int g1[], g2[];
+
+const int *f1() {
+ return g1;
+}
+
+int f2() {
+ return g2[0];
+}
Index: test/Driver/addrsig.c
===================================================================
--- test/Driver/addrsig.c
+++ test/Driver/addrsig.c
@@ -0,0 +1,8 @@
+// RUN: %clang -### -target x86_64-unknown-linux -c %s 2>&1 | FileCheck -check-prefix=ADDRSIG %s
+// RUN: %clang -### -target x86_64-unknown-linux -fno-integrated-as -c %s 2>&1 | FileCheck -check-prefix=NO-ADDRSIG %s
+// RUN: %clang -### -target x86_64-unknown-linux -fno-integrated-as -faddrsig -c %s 2>&1 | FileCheck -check-prefix=ADDRSIG %s
+// RUN: %clang -### -target x86_64-unknown-linux -fno-addrsig -c %s 2>&1 | FileCheck -check-prefix=NO-ADDRSIG %s
+// RUN: %clang -### -target x86_64-apple-darwin -c %s 2>&1 | FileCheck -check-prefix=NO-ADDRSIG %s
+
+// ADDRSIG: -faddrsig
+// NO-ADDRSIG-NOT: -faddrsig
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
