[clang] [Driver] Add -Wa, options --crel and --allow-experimental-crel (PR #97378)
Fangrui Song via cfe-commits
cfe-commits at lists.llvm.org
Mon Jul 1 19:45:09 PDT 2024
https://github.com/MaskRay created https://github.com/llvm/llvm-project/pull/97378
The two options are discussed in a few comments around
https://github.com/llvm/llvm-project/pull/91280#issuecomment-2099344079
* -Wa,--crel: error
* -Wa,--allow-experimental-crel: no-op
* -Wa,--crel,--allow-experimental-crel: enable CREL in the integrated assembler (#91280)
MIPS's little-endian n64 ABI messed up the `r_info` field in
relocations. While this could be fixed with CREL, my intention is to
avoid complication in assembler/linker. The implementation simply
doesn't allow CREL for MIPS.
Link: https://discourse.llvm.org/t/rfc-crel-a-compact-relocation-format-for-elf/77600
>From 6e47264dc3d7395b30bedeeba7c8ca2e7b376727 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Mon, 1 Jul 2024 19:44:57 -0700
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
=?UTF-8?q?l=20version?=
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Created using spr 1.3.5-bogner
---
clang/include/clang/Basic/CodeGenOptions.def | 1 +
.../clang/Basic/DiagnosticDriverKinds.td | 3 +++
clang/include/clang/Driver/Options.td | 3 +++
clang/lib/CodeGen/BackendUtil.cpp | 1 +
clang/lib/Driver/ToolChains/Clang.cpp | 18 +++++++++++++
clang/lib/Driver/ToolChains/CommonArgs.cpp | 21 ++++++++++++++++
clang/test/Driver/crel.c | 25 +++++++++++++++++++
clang/test/Misc/cc1as-crel.s | 6 +++++
clang/tools/driver/cc1as_main.cpp | 6 +++++
9 files changed, 84 insertions(+)
create mode 100644 clang/test/Driver/crel.c
create mode 100644 clang/test/Misc/cc1as-crel.s
diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
index e3f6da4a84f69..25de2204f04c0 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -36,6 +36,7 @@ VALUE_CODEGENOPT(Name, Bits, Default)
#endif
CODEGENOPT(DisableIntegratedAS, 1, 0) ///< -no-integrated-as
+CODEGENOPT(Crel, 1, 0) ///< -Wa,--crel
CODEGENOPT(RelaxELFRelocations, 1, 1) ///< -Wa,-mrelax-relocations={yes,no}
CODEGENOPT(AsmVerbose , 1, 0) ///< -dA, -fverbose-asm.
CODEGENOPT(PreserveAsmComments, 1, 1) ///< -dA, -fno-preserve-as-comments.
diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 1ca2cb85565a1..fa81a63c72231 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -801,6 +801,9 @@ def warn_drv_missing_multilib : Warning<
def note_drv_available_multilibs : Note<
"available multilibs are:%0">;
+def err_drv_experimental_crel : Error<
+ "-Wa,--allow-experimental-crel must be specified to use -Wa,--crel. CREL is experimental and takes a non-standard section type code">;
+
def warn_android_unversioned_fallback : Warning<
"using unversioned Android target directory %0 for target %1; unversioned "
"directories will not be used in Clang 19 -- provide a versioned directory "
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 1c2b8cfeef6ce..a9a451805be70 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -7027,6 +7027,9 @@ def massembler_no_warn : Flag<["-"], "massembler-no-warn">,
def massembler_fatal_warnings : Flag<["-"], "massembler-fatal-warnings">,
HelpText<"Make assembler warnings fatal">,
MarshallingInfoFlag<CodeGenOpts<"FatalWarnings">>;
+def crel : Flag<["--"], "crel">,
+ HelpText<"Enable CREL relocation format (ELF only)">,
+ MarshallingInfoFlag<CodeGenOpts<"Crel">>;
def mrelax_relocations_no : Flag<["-"], "mrelax-relocations=no">,
HelpText<"Disable x86 relax relocations">,
MarshallingInfoNegativeFlag<CodeGenOpts<"RelaxELFRelocations">>;
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 22b593e8f2b7a..9ef40c692785b 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -469,6 +469,7 @@ static bool initTargetOptions(DiagnosticsEngine &Diags,
Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;
Options.MCOptions.Dwarf64 = CodeGenOpts.Dwarf64;
Options.MCOptions.PreserveAsmComments = CodeGenOpts.PreserveAsmComments;
+ Options.MCOptions.Crel = CodeGenOpts.Crel;
Options.MCOptions.X86RelaxRelocations = CodeGenOpts.RelaxELFRelocations;
Options.MCOptions.CompressDebugSections =
CodeGenOpts.getCompressDebugSections();
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 27c451c565f2b..f098320cdb4c5 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2500,6 +2500,8 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
// arg after parsing the '-I' arg.
bool TakeNextArg = false;
+ const llvm::Triple &Triple = C.getDefaultToolChain().getTriple();
+ bool Crel = false, ExperimentalCrel = false;
bool UseRelaxRelocations = C.getDefaultToolChain().useRelaxRelocations();
bool UseNoExecStack = false;
const char *MipsTargetFeature = nullptr;
@@ -2623,6 +2625,12 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
Value == "-nocompress-debug-sections" ||
Value == "--nocompress-debug-sections") {
CmdArgs.push_back(Value.data());
+ } else if (Value == "--crel") {
+ Crel = true;
+ } else if (Value == "--no-crel") {
+ Crel = false;
+ } else if (Value == "--allow-experimental-crel") {
+ ExperimentalCrel = true;
} else if (Value == "-mrelax-relocations=yes" ||
Value == "--mrelax-relocations=yes") {
UseRelaxRelocations = true;
@@ -2688,6 +2696,16 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
}
if (ImplicitIt.size())
AddARMImplicitITArgs(Args, CmdArgs, ImplicitIt);
+ if (Crel) {
+ if (!ExperimentalCrel)
+ D.Diag(diag::err_drv_experimental_crel);
+ if (Triple.isOSBinFormatELF() && !Triple.isMIPS()) {
+ CmdArgs.push_back("--crel");
+ } else {
+ D.Diag(diag::err_drv_unsupported_opt_for_target)
+ << "-Wa,--crel" << D.getTargetTriple();
+ }
+ }
if (!UseRelaxRelocations)
CmdArgs.push_back("-mrelax-relocations=no");
if (UseNoExecStack)
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 2a4c1369f5a73..604fb89501730 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1133,6 +1133,27 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
addMachineOutlinerArgs(D, Args, CmdArgs, ToolChain.getEffectiveTriple(),
/*IsLTO=*/true, PluginOptPrefix);
+
+ for (const Arg *A : Args.filtered(options::OPT_Wa_COMMA)) {
+ bool Crel = false;
+ for (StringRef V : A->getValues()) {
+ if (V == "--crel")
+ Crel = true;
+ else if (V == "--no-crel")
+ Crel = false;
+ else
+ continue;
+ A->claim();
+ }
+ if (Crel) {
+ if (Triple.isOSBinFormatELF() && !Triple.isMIPS()) {
+ CmdArgs.push_back(Args.MakeArgString(Twine(PluginOptPrefix) + "-crel"));
+ } else {
+ D.Diag(diag::err_drv_unsupported_opt_for_target)
+ << "-Wa,--crel" << D.getTargetTriple();
+ }
+ }
+ }
}
/// Adds the '-lcgpu' and '-lmgpu' libraries to the compilation to include the
diff --git a/clang/test/Driver/crel.c b/clang/test/Driver/crel.c
new file mode 100644
index 0000000000000..a427799c9ab6f
--- /dev/null
+++ b/clang/test/Driver/crel.c
@@ -0,0 +1,25 @@
+// RUN: not %clang -### -c --target=x86_64 -Wa,--crel %s 2>&1 | FileCheck %s --check-prefix=NOEXP
+
+// NOEXP: error: -Wa,--allow-experimental-crel must be specified to use -Wa,--crel. CREL is experimental and takes a non-standard section type code
+
+// RUN: %clang -### -c --target=x86_64 -Wa,--crel,--allow-experimental-crel %s -Werror 2>&1 | FileCheck %s
+// RUN: %clang -### -c --target=x86_64 -Wa,--crel,--no-crel,--allow-experimental-crel %s -Werror 2>&1 | FileCheck %s --check-prefix=NO
+// RUN: %clang -### -c --target=x86_64 -Wa,--allow-experimental-crel %s -Werror 2>&1 | FileCheck %s --check-prefix=NO
+// RUN: not %clang -### -c --target=arm64-apple-darwin -Wa,--crel,--allow-experimental-crel %s 2>&1 | FileCheck %s --check-prefix=ERR
+// RUN: not %clang -### -c --target=mips64 -Wa,--crel,--allow-experimental-crel %s 2>&1 | FileCheck %s --check-prefix=ERR
+
+// RUN: %clang -### -c --target=aarch64 -Werror -Wa,--crel,--allow-experimental-crel -x assembler %s -Werror 2>&1 | FileCheck %s --check-prefix=ASM
+// RUN: not %clang -### -c --target=mips64 -Wa,--crel,--allow-experimental-crel -x assembler %s 2>&1 | FileCheck %s --check-prefix=ERR
+
+// CHECK: "-cc1" {{.*}}"--crel"
+// NO: "-cc1"
+// NO-NOT: "--crel"
+// ASM: "-cc1as" {{.*}}"--crel"
+// ERR: error: unsupported option '-Wa,--crel' for target '{{.*}}'
+
+/// Don't bother with --allow-experimental-crel for LTO.
+// RUN: %clang -### --target=x86_64-linux -Werror -flto -Wa,--crel %s 2>&1 | FileCheck %s --check-prefix=LTO
+// LTO: "-plugin-opt=-crel"
+
+// RUN: touch %t.o
+// RUN: not %clang -### --target=mips64-linux-gnu -flto -Wa,--crel %t.o 2>&1 | FileCheck %s --check-prefix=ERR
diff --git a/clang/test/Misc/cc1as-crel.s b/clang/test/Misc/cc1as-crel.s
new file mode 100644
index 0000000000000..78e78b09bf4c3
--- /dev/null
+++ b/clang/test/Misc/cc1as-crel.s
@@ -0,0 +1,6 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang -cc1as -triple x86_64 %s -filetype obj --crel -o %t.o
+// RUN: llvm-readelf -S %t.o | FileCheck %s
+
+// CHECK: .crel.text CREL
+call foo
diff --git a/clang/tools/driver/cc1as_main.cpp b/clang/tools/driver/cc1as_main.cpp
index ce1e181042609..4e0aa1450563e 100644
--- a/clang/tools/driver/cc1as_main.cpp
+++ b/clang/tools/driver/cc1as_main.cpp
@@ -164,6 +164,9 @@ struct AssemblerInvocation {
LLVM_PREFERRED_TYPE(bool)
unsigned EmitCompactUnwindNonCanonical : 1;
+ LLVM_PREFERRED_TYPE(bool)
+ unsigned Crel : 1;
+
/// The name of the relocation model to use.
std::string RelocationModel;
@@ -204,6 +207,7 @@ struct AssemblerInvocation {
EmbedBitcode = 0;
EmitDwarfUnwind = EmitDwarfUnwindType::Default;
EmitCompactUnwindNonCanonical = false;
+ Crel = false;
}
static bool CreateFromArgs(AssemblerInvocation &Res,
@@ -373,6 +377,7 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
Opts.EmitCompactUnwindNonCanonical =
Args.hasArg(OPT_femit_compact_unwind_non_canonical);
+ Opts.Crel = Args.hasArg(OPT_crel);
Opts.AsSecureLogFile = Args.getLastArgValue(OPT_as_secure_log_file);
@@ -430,6 +435,7 @@ static bool ExecuteAssemblerImpl(AssemblerInvocation &Opts,
MCOptions.EmitDwarfUnwind = Opts.EmitDwarfUnwind;
MCOptions.EmitCompactUnwindNonCanonical = Opts.EmitCompactUnwindNonCanonical;
MCOptions.MCSaveTempLabels = Opts.SaveTemporaryLabels;
+ MCOptions.Crel = Opts.Crel;
MCOptions.X86RelaxRelocations = Opts.RelaxELFRelocations;
MCOptions.CompressDebugSections = Opts.CompressDebugSections;
MCOptions.AsSecureLogFile = Opts.AsSecureLogFile;
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