RuntimeLibcalls: Add bitset for available libcalls #150869
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This was referenced Jul 28, 2025
arsenm
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DanielKristofKiss,
dpaoliello,
efriedma-quic,
nikic and
RKSimon
This was referenced Jul 28, 2025
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@llvm/pr-subscribers-tablegen @llvm/pr-subscribers-llvm-ir Author: Matt Arsenault (arsenm) ChangesThis is a step towards separating the set of available libcalls Full diff: https://github.com/llvm/llvm-project/pull/150869.diff 6 Files Affected:
diff --git a/llvm/include/llvm/IR/RuntimeLibcalls.h b/llvm/include/llvm/IR/RuntimeLibcalls.h
index ad3bb4eca1c56..0de7d14bd0f60 100644
--- a/llvm/include/llvm/IR/RuntimeLibcalls.h
+++ b/llvm/include/llvm/IR/RuntimeLibcalls.h
@@ -53,8 +53,64 @@ static inline auto libcall_impls() {
return enum_seq(static_cast<RTLIB::LibcallImpl>(1), RTLIB::NumLibcallImpls);
}
+/// Manage a bitset representing the list of available libcalls for a module.
+///
+/// Most of this exists because std::bitset cannot be statically constructed in
+/// a size large enough before c++23
+class LibcallImplBitset {
+private:
+ using BitWord = uint64_t;
+ static constexpr unsigned BitWordSize = sizeof(BitWord) * CHAR_BIT;
+ static constexpr size_t NumArrayElts =
+ divideCeil(RTLIB::NumLibcallImpls, BitWordSize);
+ using Storage = BitWord[NumArrayElts];
+
+ Storage Bits = {};
+
+ /// Get bitmask for \p Impl in its Bits element.
+ static constexpr BitWord getBitmask(RTLIB::LibcallImpl Impl) {
+ unsigned Idx = static_cast<unsigned>(Impl);
+ return BitWord(1) << (Idx % BitWordSize);
+ }
+
+ /// Get index of array element of Bits for \p Impl
+ static constexpr unsigned getArrayIdx(RTLIB::LibcallImpl Impl) {
+ return static_cast<unsigned>(Impl) / BitWordSize;
+ }
+
+public:
+ constexpr LibcallImplBitset() = default;
+ constexpr LibcallImplBitset(const Storage &Src) {
+ for (size_t I = 0; I != NumArrayElts; ++I)
+ Bits[I] = Src[I];
+ }
+
+ /// Check if a LibcallImpl is available.
+ constexpr bool test(RTLIB::LibcallImpl Impl) const {
+ BitWord Mask = getBitmask(Impl);
+ return (Bits[getArrayIdx(Impl)] & Mask) != 0;
+ }
+
+ /// Mark a LibcallImpl as available
+ void set(RTLIB::LibcallImpl Impl) {
+ assert(Impl != RTLIB::Unsupported && "cannot enable unsupported libcall");
+ Bits[getArrayIdx(Impl)] |= getBitmask(Impl);
+ }
+
+ /// Mark a LibcallImpl as unavailable
+ void unset(RTLIB::LibcallImpl Impl) {
+ assert(Impl != RTLIB::Unsupported && "cannot enable unsupported libcall");
+ Bits[getArrayIdx(Impl)] &= ~getBitmask(Impl);
+ }
+};
+
/// A simple container for information about the supported runtime calls.
struct RuntimeLibcallsInfo {
+private:
+ /// Bitset of libcalls a module may emit a call to.
+ LibcallImplBitset AvailableLibcallImpls;
+
+public:
explicit RuntimeLibcallsInfo(
const Triple &TT,
ExceptionHandling ExceptionModel = ExceptionHandling::None,
@@ -132,6 +188,10 @@ struct RuntimeLibcallsInfo {
return ImplToLibcall[Impl];
}
+ bool isAvailable(RTLIB::LibcallImpl Impl) const {
+ return AvailableLibcallImpls.test(Impl);
+ }
+
/// Check if this is valid libcall for the current module, otherwise
/// RTLIB::Unsupported.
RTLIB::LibcallImpl getSupportedLibcallImpl(StringRef FuncName) const;
diff --git a/llvm/lib/IR/RuntimeLibcalls.cpp b/llvm/lib/IR/RuntimeLibcalls.cpp
index 8c90c52141dc7..569f63f28db77 100644
--- a/llvm/lib/IR/RuntimeLibcalls.cpp
+++ b/llvm/lib/IR/RuntimeLibcalls.cpp
@@ -114,12 +114,8 @@ RuntimeLibcallsInfo::getSupportedLibcallImpl(StringRef FuncName) const {
for (auto I = Range.begin(); I != Range.end(); ++I) {
RTLIB::LibcallImpl Impl =
static_cast<RTLIB::LibcallImpl>(I - RuntimeLibcallNameOffsets.begin());
-
- // FIXME: This should not depend on looking up ImplToLibcall, only the list
- // of libcalls for the module.
- RTLIB::LibcallImpl Recognized = LibcallImpls[ImplToLibcall[Impl]];
- if (Recognized != RTLIB::Unsupported)
- return Recognized;
+ if (isAvailable(Impl))
+ return Impl;
}
return RTLIB::Unsupported;
diff --git a/llvm/test/TableGen/RuntimeLibcallEmitter-calling-conv.td b/llvm/test/TableGen/RuntimeLibcallEmitter-calling-conv.td
index 49d5ecaa0e5c5..c2aeae285a427 100644
--- a/llvm/test/TableGen/RuntimeLibcallEmitter-calling-conv.td
+++ b/llvm/test/TableGen/RuntimeLibcallEmitter-calling-conv.td
@@ -48,6 +48,11 @@ def MSP430LibraryWithCondCC : SystemRuntimeLibrary<isMSP430,
// CHECK-NEXT: Entry = DefaultCC;
// CHECK-NEXT: }
// CHECK-EMPTY:
+// CHECK-NEXT: static constexpr LibcallImplBitset SystemAvailableImpls({
+// CHECK-NEXT: 0x0000000000001a
+// CHECK-NEXT: });
+// CHECK-NEXT: AvailableLibcallImpls = SystemAvailableImpls;
+// CHECK-EMPTY:
// CHECK-NEXT: static const LibcallImplPair LibraryCalls[] = {
// CHECK-NEXT: {RTLIB::MALLOC, RTLIB::malloc}, // malloc
// CHECK-NEXT: };
@@ -70,6 +75,11 @@ def MSP430LibraryWithCondCC : SystemRuntimeLibrary<isMSP430,
// CHECK-NEXT: }
// CHECK-EMPTY:
// CHECK-NEXT: if (TT.getArch() == Triple::avr) {
+// CHECK-NEXT: static constexpr LibcallImplBitset SystemAvailableImpls({
+// CHECK-NEXT: 0x0000000000001a
+// CHECK-NEXT: });
+// CHECK-NEXT: AvailableLibcallImpls = SystemAvailableImpls;
+// CHECK-EMPTY:
// CHECK-NEXT: static const LibcallImplPair LibraryCalls[] = {
// CHECK-NEXT: {RTLIB::MALLOC, RTLIB::malloc}, // malloc
// CHECK-NEXT: };
@@ -92,6 +102,11 @@ def MSP430LibraryWithCondCC : SystemRuntimeLibrary<isMSP430,
// CHECK-NEXT: }
// CHECK-EMPTY:
// CHECK-NEXT: if (TT.getArch() == Triple::msp430) {
+// CHECK-NEXT: static constexpr LibcallImplBitset SystemAvailableImpls({
+// CHECK-NEXT: 0x0000000000001a
+// CHECK-NEXT: });
+// CHECK-NEXT: AvailableLibcallImpls = SystemAvailableImpls;
+// CHECK-EMPTY:
// CHECK-NEXT: static const LibcallImplPair LibraryCalls[] = {
// CHECK-NEXT: {RTLIB::MALLOC, RTLIB::malloc}, // malloc
// CHECK-NEXT: };
diff --git a/llvm/test/TableGen/RuntimeLibcallEmitter-conflict-warning.td b/llvm/test/TableGen/RuntimeLibcallEmitter-conflict-warning.td
index 00c9d53846326..2a8739335a8dd 100644
--- a/llvm/test/TableGen/RuntimeLibcallEmitter-conflict-warning.td
+++ b/llvm/test/TableGen/RuntimeLibcallEmitter-conflict-warning.td
@@ -25,6 +25,11 @@ def dup1 : RuntimeLibcallImpl<ANOTHER_DUP>;
// func_a and func_b both provide SOME_FUNC.
// CHECK: if (isTargetArchA()) {
+// CHECK-NEXT: static constexpr LibcallImplBitset SystemAvailableImpls({
+// CHECK-NEXT: 0x00000000000018
+// CHECK-NEXT: });
+// CHECK-NEXT: AvailableLibcallImpls = SystemAvailableImpls;
+// CHECK-EMPTY:
// CHECK-NEXT: static const LibcallImplPair LibraryCalls[] = {
// CHECK-NEXT: {RTLIB::SOME_FUNC, RTLIB::func_b}, // func_b
// CHECK-NEXT: };
@@ -35,6 +40,11 @@ def TheSystemLibraryA : SystemRuntimeLibrary<isTargetArchA,
>;
// CHECK: if (isTargetArchB()) {
+// CHECK-NEXT: static constexpr LibcallImplBitset SystemAvailableImpls({
+// CHECK-NEXT: 0x00000000000058
+// CHECK-NEXT: });
+// CHECK-NEXT: AvailableLibcallImpls = SystemAvailableImpls;
+// CHECK-EMPTY:
// CHECK-NEXT: static const LibcallImplPair LibraryCalls[] = {
// CHECK-NEXT: {RTLIB::OTHER_FUNC, RTLIB::other_func}, // other_func
// CHECK-NEXT: {RTLIB::SOME_FUNC, RTLIB::func_a}, // func_a
@@ -46,6 +56,11 @@ def TheSystemLibraryB : SystemRuntimeLibrary<isTargetArchB,
>;
// CHECK: if (isTargetArchC()) {
+// CHECK-NEXT: static constexpr LibcallImplBitset SystemAvailableImpls({
+// CHECK-NEXT: 0x0000000000007e
+// CHECK-NEXT: });
+// CHECK-NEXT: AvailableLibcallImpls = SystemAvailableImpls;
+// CHECK-EMPTY:
// CHECK-NEXT: static const LibcallImplPair LibraryCalls[] = {
// CHECK-NEXT: {RTLIB::ANOTHER_DUP, RTLIB::dup1}, // dup1
// CHECK-NEXT: {RTLIB::OTHER_FUNC, RTLIB::other_func}, // other_func
diff --git a/llvm/test/TableGen/RuntimeLibcallEmitter.td b/llvm/test/TableGen/RuntimeLibcallEmitter.td
index 642f8b85a89c6..fe4159201574b 100644
--- a/llvm/test/TableGen/RuntimeLibcallEmitter.td
+++ b/llvm/test/TableGen/RuntimeLibcallEmitter.td
@@ -157,6 +157,11 @@ def BlahLibrary : SystemRuntimeLibrary<isBlahArch, (add calloc, LibraryWithCondi
// CHECK-NEXT: };
// CHECK-EMPTY:
// CHECK-NEXT: if (TT.getArch() == Triple::blah) {
+// CHECK-NEXT: static constexpr LibcallImplBitset SystemAvailableImpls({
+// CHECK-NEXT: 0x000000000000fc
+// CHECK-NEXT: });
+// CHECK-NEXT: AvailableLibcallImpls = SystemAvailableImpls;
+// CHECK-EMPTY:
// CHECK-NEXT: static const LibcallImplPair LibraryCalls[] = {
// CHECK-NEXT: {RTLIB::BZERO, RTLIB::bzero}, // bzero
// CHECK-NEXT: {RTLIB::CALLOC, RTLIB::calloc}, // calloc
@@ -194,6 +199,11 @@ def BlahLibrary : SystemRuntimeLibrary<isBlahArch, (add calloc, LibraryWithCondi
// CHECK-NEXT: }
// CHECK-EMPTY:
// CHECK-NEXT: if (TT.getArch() == Triple::buzz) {
+// CHECK-NEXT: static constexpr LibcallImplBitset SystemAvailableImpls({
+// CHECK-NEXT: 0x00000000000118
+// CHECK-NEXT: });
+// CHECK-NEXT: AvailableLibcallImpls = SystemAvailableImpls;
+// CHECK-EMPTY:
// CHECK-NEXT: static const LibcallImplPair LibraryCalls[] = {
// CHECK-NEXT: {RTLIB::SHL_I32, RTLIB::__ashlsi3}, // __ashlsi3
// CHECK-NEXT: {RTLIB::SQRT_F80, RTLIB::sqrtl_f80}, // sqrtl
@@ -208,6 +218,11 @@ def BlahLibrary : SystemRuntimeLibrary<isBlahArch, (add calloc, LibraryWithCondi
// CHECK-NEXT: }
// CHECK-EMPTY:
// CHECK-NEXT: if (TT.getArch() == Triple::foo) {
+// CHECK-NEXT: static constexpr LibcallImplBitset SystemAvailableImpls({
+// CHECK-NEXT: 0x000000000000a4
+// CHECK-NEXT: });
+// CHECK-NEXT: AvailableLibcallImpls = SystemAvailableImpls;
+// CHECK-EMPTY:
// CHECK-NEXT: static const LibcallImplPair LibraryCalls[] = {
// CHECK-NEXT: {RTLIB::BZERO, RTLIB::bzero}, // bzero
// CHECK-NEXT: {RTLIB::SQRT_F128, RTLIB::sqrtl_f128}, // sqrtl
@@ -232,6 +247,11 @@ def BlahLibrary : SystemRuntimeLibrary<isBlahArch, (add calloc, LibraryWithCondi
// CHECK-NEXT: }
// CHECK-EMPTY:
// CHECK-NEXT: if (TT.getArch() == Triple::simple) {
+// CHECK-NEXT: static constexpr LibcallImplBitset SystemAvailableImpls({
+// CHECK-NEXT: 0x00000000000158
+// CHECK-NEXT: });
+// CHECK-NEXT: AvailableLibcallImpls = SystemAvailableImpls;
+// CHECK-EMPTY:
// CHECK-NEXT: static const LibcallImplPair LibraryCalls[] = {
// CHECK-NEXT: {RTLIB::CALLOC, RTLIB::calloc}, // calloc
// CHECK-NEXT: {RTLIB::SHL_I32, RTLIB::__ashlsi3}, // __ashlsi3
diff --git a/llvm/utils/TableGen/Basic/RuntimeLibcallsEmitter.cpp b/llvm/utils/TableGen/Basic/RuntimeLibcallsEmitter.cpp
index 412431b96d030..853209f94ea2c 100644
--- a/llvm/utils/TableGen/Basic/RuntimeLibcallsEmitter.cpp
+++ b/llvm/utils/TableGen/Basic/RuntimeLibcallsEmitter.cpp
@@ -8,6 +8,7 @@
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/Format.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/TableGen/Error.h"
@@ -402,6 +403,10 @@ void RuntimeLibcallEmitter::emitSystemRuntimeLibrarySetCalls(
PredicateWithCC()); // No predicate or CC override first.
DenseMap<PredicateWithCC, LibcallsWithCC> Pred2Funcs;
+
+ SmallVector<uint64_t, 32> BitsetValues(
+ divideCeil(RuntimeLibcallImplDefList.size(), 64));
+
for (const Record *Elt : *Elements) {
const RuntimeLibcallImpl *LibCallImpl = getRuntimeLibcallImpl(Elt);
if (!LibCallImpl) {
@@ -410,6 +415,9 @@ void RuntimeLibcallEmitter::emitSystemRuntimeLibrarySetCalls(
continue;
}
+ size_t Idx = LibCallImpl->getEnumVal();
+ BitsetValues[Idx / 64] |= uint64_t(1) << (Idx % 64);
+
auto It = Func2Preds.find(LibCallImpl);
if (It == Func2Preds.end()) {
Pred2Funcs[PredicateWithCC()].LibcallImpls.push_back(LibCallImpl);
@@ -427,6 +435,22 @@ void RuntimeLibcallEmitter::emitSystemRuntimeLibrarySetCalls(
}
}
+ OS << " static constexpr LibcallImplBitset SystemAvailableImpls({\n"
+ << indent(6);
+
+ ListSeparator LS;
+ unsigned EntryCount = 0;
+ for (uint64_t Bits : BitsetValues) {
+ if (EntryCount++ == 4) {
+ EntryCount = 1;
+ OS << ",\n" << indent(6);
+ } else
+ OS << LS;
+ OS << format_hex(Bits, 16);
+ }
+ OS << "\n });\n"
+ " AvailableLibcallImpls = SystemAvailableImpls;\n\n";
+
SmallVector<PredicateWithCC, 0> SortedPredicates =
PredicateSorter.takeVector();
|
This is a step towards separating the set of available libcalls from the lowering decision of which call to use. Libcall recognition now directly checks availability instead of indirectly checking through the lowering table.
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This is a step towards separating the set of available libcalls
from the lowering decision of which call to use. Libcall recognition
now directly checks availability instead of indirectly checking through
the lowering table.