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[Multilib] Custom flags processing for library selection
Select library variants in the multilib system using the flags passed following the '-fmultilib-flag=' format. Multilib flags that were not passed in the command-line have their default value fed into the library selection mechanism. A warning is shown if the flag's value name is invalid. If the wrong name is close enough to any valid one, according to edit distance, the closest valid value name is suggested. Details about this change can be found in this thread: https://discourse.llvm.org/t/rfc-multilib-custom-flags/81058
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8 files changed

+328
-75
lines changed

8 files changed

+328
-75
lines changed

‎clang/include/clang/Driver/Driver.h‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -466,7 +466,7 @@ class Driver {
466466
/// ArgList.
467467
llvm::opt::InputArgList ParseArgStrings(ArrayRef<const char *> Args,
468468
bool UseDriverMode,
469-
bool &ContainsError);
469+
bool &ContainsError) const;
470470

471471
/// BuildInputs - Construct the list of inputs and their types from
472472
/// the given arguments.

‎clang/include/clang/Driver/Multilib.h‎

Lines changed: 10 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -168,9 +168,18 @@ class MultilibSet {
168168
const_iterator begin() const { return Multilibs.begin(); }
169169
const_iterator end() const { return Multilibs.end(); }
170170

171+
/// Process custom flags from \p Flags and returns an expanded flags list and
172+
/// a list of extra compilation arguments.
173+
/// Returns a pair where:
174+
/// - first: the new flags list including custom flags after processing.
175+
/// - second: the extra compilation arguments to be fed to the driver.
176+
std::pair<Multilib::flags_list, SmallVector<StringRef>>
177+
processCustomFlags(const Driver &D, const Multilib::flags_list &Flags) const;
178+
171179
/// Select compatible variants, \returns false if none are compatible
172180
bool select(const Driver &D, const Multilib::flags_list &Flags,
173-
llvm::SmallVectorImpl<Multilib> &) const;
181+
llvm::SmallVectorImpl<Multilib> &,
182+
llvm::SmallVector<StringRef> * = nullptr) const;
174183

175184
unsigned size() const { return Multilibs.size(); }
176185

‎clang/include/clang/Driver/ToolChain.h‎

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -686,6 +686,13 @@ class ToolChain {
686686
/// Add warning options that need to be passed to cc1 for this target.
687687
virtual void addClangWarningOptions(llvm::opt::ArgStringList &CC1Args) const;
688688

689+
// Get the list of extra driver arguments strings requested by the multilib
690+
// configuration.
691+
virtual SmallVector<std::string>
692+
getMultilibDriverArgsStr(llvm::opt::ArgList &Args) const {
693+
return {};
694+
};
695+
689696
// GetRuntimeLibType - Determine the runtime library type to use with the
690697
// given compilation arguments.
691698
virtual RuntimeLibType

‎clang/lib/Driver/Driver.cpp‎

Lines changed: 76 additions & 65 deletions
Original file line numberDiff line numberDiff line change
@@ -264,7 +264,7 @@ void Driver::setDriverMode(StringRef Value) {
264264
}
265265

266266
InputArgList Driver::ParseArgStrings(ArrayRef<const char *> ArgStrings,
267-
bool UseDriverMode, bool &ContainsError) {
267+
bool UseDriverMode, bool &ContainsError) const {
268268
llvm::PrettyStackTraceString CrashInfo("Command line argument parsing");
269269
ContainsError = false;
270270

@@ -1397,8 +1397,8 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
13971397
bool HasConfigFileTail = !ContainsError && CfgOptionsTail;
13981398

13991399
// All arguments, from both config file and command line.
1400-
InputArgList Args =
1401-
HasConfigFileHead ? std::move(*CfgOptionsHead) : std::move(*CLOptions);
1400+
auto UArgs = std::make_unique<InputArgList>(HasConfigFileHead ? std::move(*CfgOptionsHead) : std::move(*CLOptions));
1401+
InputArgList &Args = *UArgs;
14021402

14031403
if (HasConfigFileHead)
14041404
for (auto *Opt : *CLOptions)
@@ -1426,52 +1426,6 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
14261426
}
14271427
}
14281428

1429-
// Check for working directory option before accessing any files
1430-
if (Arg *WD = Args.getLastArg(options::OPT_working_directory))
1431-
if (VFS->setCurrentWorkingDirectory(WD->getValue()))
1432-
Diag(diag::err_drv_unable_to_set_working_directory) << WD->getValue();
1433-
1434-
// Check for missing include directories.
1435-
if (!Diags.isIgnored(diag::warn_missing_include_dirs, SourceLocation())) {
1436-
for (auto IncludeDir : Args.getAllArgValues(options::OPT_I_Group)) {
1437-
if (!VFS->exists(IncludeDir))
1438-
Diag(diag::warn_missing_include_dirs) << IncludeDir;
1439-
}
1440-
}
1441-
1442-
// FIXME: This stuff needs to go into the Compilation, not the driver.
1443-
bool CCCPrintPhases;
1444-
1445-
// -canonical-prefixes, -no-canonical-prefixes are used very early in main.
1446-
Args.ClaimAllArgs(options::OPT_canonical_prefixes);
1447-
Args.ClaimAllArgs(options::OPT_no_canonical_prefixes);
1448-
1449-
// f(no-)integated-cc1 is also used very early in main.
1450-
Args.ClaimAllArgs(options::OPT_fintegrated_cc1);
1451-
Args.ClaimAllArgs(options::OPT_fno_integrated_cc1);
1452-
1453-
// Ignore -pipe.
1454-
Args.ClaimAllArgs(options::OPT_pipe);
1455-
1456-
// Extract -ccc args.
1457-
//
1458-
// FIXME: We need to figure out where this behavior should live. Most of it
1459-
// should be outside in the client; the parts that aren't should have proper
1460-
// options, either by introducing new ones or by overloading gcc ones like -V
1461-
// or -b.
1462-
CCCPrintPhases = Args.hasArg(options::OPT_ccc_print_phases);
1463-
CCCPrintBindings = Args.hasArg(options::OPT_ccc_print_bindings);
1464-
if (const Arg *A = Args.getLastArg(options::OPT_ccc_gcc_name))
1465-
CCCGenericGCCName = A->getValue();
1466-
1467-
// Process -fproc-stat-report options.
1468-
if (const Arg *A = Args.getLastArg(options::OPT_fproc_stat_report_EQ)) {
1469-
CCPrintProcessStats = true;
1470-
CCPrintStatReportFilename = A->getValue();
1471-
}
1472-
if (Args.hasArg(options::OPT_fproc_stat_report))
1473-
CCPrintProcessStats = true;
1474-
14751429
// FIXME: TargetTriple is used by the target-prefixed calls to as/ld
14761430
// and getToolChain is const.
14771431
if (IsCLMode()) {
@@ -1529,6 +1483,79 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
15291483
TargetTriple = A->getValue();
15301484
if (const Arg *A = Args.getLastArg(options::OPT_ccc_install_dir))
15311485
Dir = Dir = A->getValue();
1486+
if (const Arg *A = Args.getLastArg(options::OPT__sysroot_EQ))
1487+
SysRoot = A->getValue();
1488+
if (const Arg *A = Args.getLastArg(options::OPT_resource_dir))
1489+
ResourceDir = A->getValue();
1490+
if (const Arg *A = Args.getLastArg(options::OPT__dyld_prefix_EQ))
1491+
DyldPrefix = A->getValue();
1492+
1493+
setLTOMode(Args);
1494+
1495+
// Owned by the host.
1496+
const ToolChain &TC =
1497+
getToolChain(Args, computeTargetTriple(*this, TargetTriple, Args));
1498+
1499+
SmallVector<std::string> MultilibDriverArgsStr =
1500+
TC.getMultilibDriverArgsStr(Args);
1501+
SmallVector<const char *> MLArgsChar(
1502+
llvm::map_range(MultilibDriverArgsStr, [&Args](const auto &S) {
1503+
return Args.MakeArgString(S);
1504+
}));
1505+
bool MLContainsError;
1506+
auto MultilibDriverArgList = std::make_unique<InputArgList>(
1507+
ParseArgStrings(MLArgsChar, /*UseDriverMode=*/false, MLContainsError));
1508+
if (!MLContainsError)
1509+
for (auto *Opt : *MultilibDriverArgList) {
1510+
appendOneArg(Args, Opt, nullptr);
1511+
}
1512+
1513+
// Check for working directory option before accessing any files
1514+
if (Arg *WD = Args.getLastArg(options::OPT_working_directory))
1515+
if (VFS->setCurrentWorkingDirectory(WD->getValue()))
1516+
Diag(diag::err_drv_unable_to_set_working_directory) << WD->getValue();
1517+
1518+
// Check for missing include directories.
1519+
if (!Diags.isIgnored(diag::warn_missing_include_dirs, SourceLocation())) {
1520+
for (auto IncludeDir : Args.getAllArgValues(options::OPT_I_Group)) {
1521+
if (!VFS->exists(IncludeDir))
1522+
Diag(diag::warn_missing_include_dirs) << IncludeDir;
1523+
}
1524+
}
1525+
1526+
// FIXME: This stuff needs to go into the Compilation, not the driver.
1527+
bool CCCPrintPhases;
1528+
1529+
// -canonical-prefixes, -no-canonical-prefixes are used very early in main.
1530+
Args.ClaimAllArgs(options::OPT_canonical_prefixes);
1531+
Args.ClaimAllArgs(options::OPT_no_canonical_prefixes);
1532+
1533+
// f(no-)integated-cc1 is also used very early in main.
1534+
Args.ClaimAllArgs(options::OPT_fintegrated_cc1);
1535+
Args.ClaimAllArgs(options::OPT_fno_integrated_cc1);
1536+
1537+
// Ignore -pipe.
1538+
Args.ClaimAllArgs(options::OPT_pipe);
1539+
1540+
// Extract -ccc args.
1541+
//
1542+
// FIXME: We need to figure out where this behavior should live. Most of it
1543+
// should be outside in the client; the parts that aren't should have proper
1544+
// options, either by introducing new ones or by overloading gcc ones like -V
1545+
// or -b.
1546+
CCCPrintPhases = Args.hasArg(options::OPT_ccc_print_phases);
1547+
CCCPrintBindings = Args.hasArg(options::OPT_ccc_print_bindings);
1548+
if (const Arg *A = Args.getLastArg(options::OPT_ccc_gcc_name))
1549+
CCCGenericGCCName = A->getValue();
1550+
1551+
// Process -fproc-stat-report options.
1552+
if (const Arg *A = Args.getLastArg(options::OPT_fproc_stat_report_EQ)) {
1553+
CCPrintProcessStats = true;
1554+
CCPrintStatReportFilename = A->getValue();
1555+
}
1556+
if (Args.hasArg(options::OPT_fproc_stat_report))
1557+
CCPrintProcessStats = true;
1558+
15321559
for (const Arg *A : Args.filtered(options::OPT_B)) {
15331560
A->claim();
15341561
PrefixDirs.push_back(A->getValue(0));
@@ -1543,13 +1570,6 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
15431570
CompilerPath = Split.second;
15441571
}
15451572
}
1546-
if (const Arg *A = Args.getLastArg(options::OPT__sysroot_EQ))
1547-
SysRoot = A->getValue();
1548-
if (const Arg *A = Args.getLastArg(options::OPT__dyld_prefix_EQ))
1549-
DyldPrefix = A->getValue();
1550-
1551-
if (const Arg *A = Args.getLastArg(options::OPT_resource_dir))
1552-
ResourceDir = A->getValue();
15531573

15541574
if (const Arg *A = Args.getLastArg(options::OPT_save_temps_EQ)) {
15551575
SaveTemps = llvm::StringSwitch<SaveTempsMode>(A->getValue())
@@ -1569,8 +1589,6 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
15691589
Offload = OffloadHostDevice;
15701590
}
15711591

1572-
setLTOMode(Args);
1573-
15741592
// Process -fembed-bitcode= flags.
15751593
if (Arg *A = Args.getLastArg(options::OPT_fembed_bitcode_EQ)) {
15761594
StringRef Name = A->getValue();
@@ -1624,16 +1642,9 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
16241642
}
16251643
}
16261644

1627-
std::unique_ptr<llvm::opt::InputArgList> UArgs =
1628-
std::make_unique<InputArgList>(std::move(Args));
1629-
16301645
// Perform the default argument translations.
16311646
DerivedArgList *TranslatedArgs = TranslateInputArgs(*UArgs);
16321647

1633-
// Owned by the host.
1634-
const ToolChain &TC = getToolChain(
1635-
*UArgs, computeTargetTriple(*this, TargetTriple, *UArgs));
1636-
16371648
// Check if the environment version is valid except wasm case.
16381649
llvm::Triple Triple = TC.getTriple();
16391650
if (!Triple.isWasm()) {

‎clang/lib/Driver/Multilib.cpp‎

Lines changed: 133 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -11,6 +11,7 @@
1111
#include "clang/Driver/Driver.h"
1212
#include "llvm/ADT/DenseSet.h"
1313
#include "llvm/ADT/SmallSet.h"
14+
#include "llvm/ADT/SmallString.h"
1415
#include "llvm/ADT/StringRef.h"
1516
#include "llvm/Support/Compiler.h"
1617
#include "llvm/Support/ErrorHandling.h"
@@ -92,12 +93,141 @@ MultilibSet &MultilibSet::FilterOut(FilterCallback F) {
9293

9394
void MultilibSet::push_back(const Multilib &M) { Multilibs.push_back(M); }
9495

95-
bool MultilibSet::select(const Driver &D, const Multilib::flags_list &Flags,
96-
llvm::SmallVectorImpl<Multilib> &Selected) const {
97-
llvm::StringSet<> FlagSet(expandFlags(Flags));
96+
static void DiagnoseUnclaimedMultilibCustomFlags(
97+
const Driver &D, const SmallVector<StringRef> &UnclaimedCustomFlagValues,
98+
const SmallVector<custom_flag::DeclarationPtr> &CustomFlagDecls) {
99+
struct EditDistanceInfo {
100+
StringRef FlagValue;
101+
unsigned EditDistance;
102+
};
103+
const unsigned MaxEditDistance = 5;
104+
105+
for (StringRef Unclaimed : UnclaimedCustomFlagValues) {
106+
std::optional<EditDistanceInfo> BestCandidate;
107+
for (const auto &Decl : CustomFlagDecls) {
108+
for (const auto &Value : Decl->ValueList) {
109+
const std::string &FlagValueName = Value.Name;
110+
unsigned EditDistance =
111+
Unclaimed.edit_distance(FlagValueName, /*AllowReplacements=*/true,
112+
/*MaxEditDistance=*/MaxEditDistance);
113+
if (!BestCandidate || (EditDistance <= MaxEditDistance &&
114+
EditDistance < BestCandidate->EditDistance)) {
115+
BestCandidate = {FlagValueName, EditDistance};
116+
}
117+
}
118+
}
119+
if (!BestCandidate)
120+
D.Diag(clang::diag::err_drv_unsupported_opt)
121+
<< (custom_flag::Prefix + Unclaimed).str();
122+
else
123+
D.Diag(clang::diag::err_drv_unsupported_opt_with_suggestion)
124+
<< (custom_flag::Prefix + Unclaimed).str()
125+
<< (custom_flag::Prefix + BestCandidate->FlagValue).str();
126+
}
127+
}
128+
129+
namespace clang::driver::custom_flag {
130+
// Map implemented using linear searches as the expected size is too small for
131+
// the overhead of a search tree or a hash table.
132+
class ValueNameToDetailMap {
133+
SmallVector<std::pair<StringRef, const ValueDetail *>> Mapping;
134+
135+
public:
136+
template <typename It>
137+
ValueNameToDetailMap(It FlagDeclsBegin, It FlagDeclsEnd) {
138+
for (auto DeclIt = FlagDeclsBegin; DeclIt != FlagDeclsEnd; ++DeclIt) {
139+
const DeclarationPtr &Decl = *DeclIt;
140+
for (const auto &Value : Decl->ValueList)
141+
Mapping.emplace_back(Value.Name, &Value);
142+
}
143+
}
144+
145+
const ValueDetail *get(StringRef Key) const {
146+
auto Iter = llvm::find_if(
147+
Mapping, [&](const auto &Pair) { return Pair.first == Key; });
148+
return Iter != Mapping.end() ? Iter->second : nullptr;
149+
}
150+
};
151+
} // namespace clang::driver::custom_flag
152+
153+
std::pair<Multilib::flags_list, SmallVector<StringRef>>
154+
MultilibSet::processCustomFlags(const Driver &D,
155+
const Multilib::flags_list &Flags) const {
156+
Multilib::flags_list Result;
157+
SmallVector<StringRef> CompilationArgs;
158+
159+
// Custom flag values detected in the flags list
160+
SmallVector<const custom_flag::ValueDetail *> ClaimedCustomFlagValues;
161+
162+
// Arguments to -fmultilib-flag=<arg> that don't correspond to any valid
163+
// custom flag value. An error will be printed out for each of these.
164+
SmallVector<StringRef> UnclaimedCustomFlagValueStrs;
165+
166+
const auto ValueNameToValueDetail = custom_flag::ValueNameToDetailMap(
167+
CustomFlagDecls.begin(), CustomFlagDecls.end());
168+
169+
for (StringRef Flag : Flags) {
170+
if (!Flag.starts_with(custom_flag::Prefix)) {
171+
Result.push_back(Flag.str());
172+
continue;
173+
}
174+
175+
StringRef CustomFlagValueStr = Flag.substr(custom_flag::Prefix.size());
176+
const custom_flag::ValueDetail *Detail =
177+
ValueNameToValueDetail.get(CustomFlagValueStr);
178+
if (Detail)
179+
ClaimedCustomFlagValues.push_back(Detail);
180+
else
181+
UnclaimedCustomFlagValueStrs.push_back(CustomFlagValueStr);
182+
}
183+
184+
// Set of custom flag declarations for which a value was passed in the flags
185+
// list. This is used to, firstly, detect multiple values for the same flag
186+
// declaration (in this case, the last one wins), and secondly, to detect
187+
// which declarations had no value passed in (in this case, the default value
188+
// is selected).
189+
llvm::SmallSet<custom_flag::DeclarationPtr, 32> TriggeredCustomFlagDecls;
190+
191+
// Detect multiple values for the same flag declaration. Last one wins.
192+
for (auto *CustomFlagValue : llvm::reverse(ClaimedCustomFlagValues)) {
193+
if (!TriggeredCustomFlagDecls.insert(CustomFlagValue->Decl).second)
194+
continue;
195+
Result.push_back(std::string(custom_flag::Prefix) + CustomFlagValue->Name);
196+
if (CustomFlagValue->DriverArgs)
197+
CompilationArgs.append(CustomFlagValue->DriverArgs->begin(),
198+
CustomFlagValue->DriverArgs->end());
199+
}
200+
201+
// Detect flag declarations with no value passed in. Select default value.
202+
for (const auto &Decl : CustomFlagDecls) {
203+
if (TriggeredCustomFlagDecls.contains(Decl))
204+
continue;
205+
custom_flag::ValueDetail &CustomFlagValue =
206+
Decl->ValueList[*Decl->DefaultValueIdx];
207+
Result.push_back(std::string(custom_flag::Prefix) + CustomFlagValue.Name);
208+
if (CustomFlagValue.DriverArgs)
209+
CompilationArgs.append(CustomFlagValue.DriverArgs->begin(),
210+
CustomFlagValue.DriverArgs->end());
211+
}
212+
213+
DiagnoseUnclaimedMultilibCustomFlags(D, UnclaimedCustomFlagValueStrs,
214+
CustomFlagDecls);
215+
216+
return {Result, CompilationArgs};
217+
}
218+
219+
bool MultilibSet::select(
220+
const Driver &D, const Multilib::flags_list &Flags,
221+
llvm::SmallVectorImpl<Multilib> &Selected,
222+
llvm::SmallVector<StringRef> *CustomFlagCompilationArgs) const {
223+
auto [FlagsWithCustom, CFCompilationArgs] = processCustomFlags(D, Flags);
224+
llvm::StringSet<> FlagSet(expandFlags(FlagsWithCustom));
98225
Selected.clear();
99226
bool AnyErrors = false;
100227

228+
if (CustomFlagCompilationArgs)
229+
*CustomFlagCompilationArgs = std::move(CFCompilationArgs);
230+
101231
// Decide which multilibs we're going to select at all.
102232
llvm::DenseSet<StringRef> ExclusiveGroupsSelected;
103233
for (const Multilib &M : llvm::reverse(Multilibs)) {

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