RuntimeLibcalls: Add stub API for getting function signatures

Eventually this should be generated by tablegen for all functions.
For now add a manually implementation for sincos_stret, which I
have an immediate use for. This will allow pulling repeated code
across targets into shared call sequence code.

Also add sqrt just to make sure we can handle adding return attributes
on the declaration.

Author: arsenm

llvm/include/llvm/IR/RuntimeLibcalls.h

@@ -186,6 +186,13 @@ struct RuntimeLibcallsInfo {
     return RTLIB::Unsupported;
   }
 
+  /// \returns the function type and attributes for the \p LibcallImpl,
+  /// depending on the target \p TT. If the function has incomplete type
+  /// information, return nullptr for the function type.
+  std::pair<FunctionType *, AttributeList>
+  getFunctionTy(LLVMContext &Ctx, const Triple &TT, const DataLayout &DL,
+                RTLIB::LibcallImpl LibcallImpl) const;
+
 private:
   LLVM_ABI static iota_range<RTLIB::LibcallImpl>
   lookupLibcallImplNameImpl(StringRef Name);

llvm/lib/IR/RuntimeLibcalls.cpp

@@ -7,7 +7,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/IR/RuntimeLibcalls.h"
+#include "llvm/ADT/FloatingPointMode.h"
 #include "llvm/ADT/StringTable.h"
+#include "llvm/IR/DataLayout.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/xxhash.h"
 #include "llvm/TargetParser/ARMTargetParser.h"
@@ -72,3 +74,80 @@ bool RuntimeLibcallsInfo::darwinHasExp10(const Triple &TT) {
     return false;
   }
 }
+
+std::pair<FunctionType *, AttributeList>
+RuntimeLibcallsInfo::getFunctionTy(LLVMContext &Ctx, const Triple &TT,
+                                   const DataLayout &DL,
+                                   RTLIB::LibcallImpl LibcallImpl) const {
+  static constexpr Attribute::AttrKind CommonFnAttrs[] = {
+      Attribute::NoCallback, Attribute::NoFree, Attribute::NoSync,
+      Attribute::NoUnwind, Attribute::WillReturn};
+
+  switch (LibcallImpl) {
+  case RTLIB::impl___sincos_stret:
+  case RTLIB::impl___sincosf_stret: {
+    if (!darwinHasSinCosStret(TT)) // Non-darwin currently unexpected
+      return {};
+
+    Type *ScalarTy = LibcallImpl == RTLIB::impl___sincosf_stret
+                         ? Type::getFloatTy(Ctx)
+                         : Type::getDoubleTy(Ctx);
+
+    AttrBuilder FuncAttrBuilder(Ctx);
+    for (Attribute::AttrKind Attr : CommonFnAttrs)
+      FuncAttrBuilder.addAttribute(Attr);
+
+    const bool UseSret =
+        TT.isX86_32() || ((TT.isARM() || TT.isThumb()) &&
+                          ARM::computeTargetABI(TT) == ARM::ARM_ABI_APCS);
+
+    FuncAttrBuilder.addMemoryAttr(MemoryEffects::argumentOrErrnoMemOnly(
+        UseSret ? ModRefInfo::Mod : ModRefInfo::NoModRef, ModRefInfo::Mod));
+
+    AttributeList Attrs;
+    Attrs = Attrs.addFnAttributes(Ctx, FuncAttrBuilder);
+
+    if (UseSret) {
+      AttrBuilder AttrBuilder(Ctx);
+      StructType *StructTy = StructType::get(ScalarTy, ScalarTy);
+      AttrBuilder.addStructRetAttr(StructTy);
+      AttrBuilder.addAlignmentAttr(DL.getABITypeAlign(StructTy));
+      FunctionType *FuncTy = FunctionType::get(
+          Type::getVoidTy(Ctx), {DL.getAllocaPtrType(Ctx), ScalarTy}, false);
+
+      return {FuncTy, Attrs.addParamAttributes(Ctx, 0, AttrBuilder)};
+    }
+
+    Type *RetTy =
+        LibcallImpl == RTLIB::impl___sincosf_stret && TT.isX86_64()
+            ? static_cast<Type *>(FixedVectorType::get(ScalarTy, 2))
+            : static_cast<Type *>(StructType::get(ScalarTy, ScalarTy));
+
+    return {FunctionType::get(RetTy, {ScalarTy}, false), Attrs};
+  }
+  case RTLIB::impl_sqrtf:
+  case RTLIB::impl_sqrt: {
+    AttrBuilder FuncAttrBuilder(Ctx);
+
+    for (Attribute::AttrKind Attr : CommonFnAttrs)
+      FuncAttrBuilder.addAttribute(Attr);
+    FuncAttrBuilder.addMemoryAttr(MemoryEffects::errnoMemOnly(ModRefInfo::Mod));
+
+    AttributeList Attrs;
+    Attrs = Attrs.addFnAttributes(Ctx, FuncAttrBuilder);
+
+    Type *ScalarTy = LibcallImpl == RTLIB::impl_sqrtf ? Type::getFloatTy(Ctx)
+                                                      : Type::getDoubleTy(Ctx);
+    FunctionType *FuncTy = FunctionType::get(ScalarTy, {ScalarTy}, false);
+
+    Attrs = Attrs.addRetAttribute(
+        Ctx, Attribute::getWithNoFPClass(Ctx, fcNegInf | fcNegSubnormal |
+                                                  fcNegNormal));
+    return {FuncTy, Attrs};
+  }
+  default:
+    return {};
+  }
+
+  return {};
+}

llvm/lib/Transforms/Utils/DeclareRuntimeLibcalls.cpp

@@ -16,22 +16,62 @@
 
 using namespace llvm;
 
+static void mergeAttributes(LLVMContext &Ctx, const Module &M,
+                            const DataLayout &DL, const Triple &TT,
+                            Function *Func, FunctionType *FuncTy,
+                            AttributeList FuncAttrs) {
+  AttributeList OldAttrs = Func->getAttributes();
+  AttributeList NewAttrs = OldAttrs;
+
+  {
+    AttrBuilder OldBuilder(Ctx, OldAttrs.getFnAttrs());
+    AttrBuilder NewBuilder(Ctx, FuncAttrs.getFnAttrs());
+    OldBuilder.merge(NewBuilder);
+    NewAttrs = NewAttrs.addFnAttributes(Ctx, OldBuilder);
+  }
+
+  {
+    AttrBuilder OldBuilder(Ctx, OldAttrs.getRetAttrs());
+    AttrBuilder NewBuilder(Ctx, FuncAttrs.getRetAttrs());
+    OldBuilder.merge(NewBuilder);
+    NewAttrs = NewAttrs.addRetAttributes(Ctx, OldBuilder);
+  }
+
+  for (unsigned I = 0, E = FuncTy->getNumParams(); I != E; ++I) {
+    AttrBuilder OldBuilder(Ctx, OldAttrs.getParamAttrs(I));
+    AttrBuilder NewBuilder(Ctx, FuncAttrs.getParamAttrs(I));
+    OldBuilder.merge(NewBuilder);
+    NewAttrs = NewAttrs.addParamAttributes(Ctx, I, OldBuilder);
+  }
+
+  Func->setAttributes(NewAttrs);
+}
+
 PreservedAnalyses DeclareRuntimeLibcallsPass::run(Module &M,
                                                   ModuleAnalysisManager &MAM) {
   RTLIB::RuntimeLibcallsInfo RTLCI(M.getTargetTriple());
   LLVMContext &Ctx = M.getContext();
+  const DataLayout &DL = M.getDataLayout();
+  const Triple &TT = M.getTargetTriple();
 
   for (RTLIB::LibcallImpl Impl : RTLCI.getLibcallImpls()) {
     if (Impl == RTLIB::Unsupported)
       continue;
 
-    // TODO: Declare with correct type, calling convention, and attributes.
+    auto [FuncTy, FuncAttrs] = RTLCI.getFunctionTy(Ctx, TT, DL, Impl);
 
-    FunctionType *FuncTy =
-        FunctionType::get(Type::getVoidTy(Ctx), {}, /*IsVarArgs=*/true);
+    // TODO: Declare with correct type, calling convention, and attributes.
+    if (!FuncTy)
+      FuncTy = FunctionType::get(Type::getVoidTy(Ctx), {}, /*IsVarArgs=*/true);
 
     StringRef FuncName = RTLCI.getLibcallImplName(Impl);
-    M.getOrInsertFunction(FuncName, FuncTy);
+
+    Function *Func =
+        cast<Function>(M.getOrInsertFunction(FuncName, FuncTy).getCallee());
+    if (Func->getFunctionType() == FuncTy) {
+      mergeAttributes(Ctx, M, DL, TT, Func, FuncTy, FuncAttrs);
+      Func->setCallingConv(RTLCI.getLibcallImplCallingConv(Impl));
+    }
   }
 
   return PreservedAnalyses::none();

llvm/test/Transforms/Util/DeclareRuntimeLibcalls/basic.ll

@@ -11,5 +11,9 @@ define float @sinf(float %x) {
 }
 
 ; CHECK: declare void @acosf(...)
+
+; CHECK: declare nofpclass(ninf nsub nnorm) float @sqrtf(float) [[SQRT_ATTRS:#[0-9]+]]
+; CHECK: declare nofpclass(ninf nsub nnorm) double @sqrt(double) [[SQRT_ATTRS:#[0-9]+]]
+
 ; CHECK: declare void @__umodti3(...)
 

llvm/test/Transforms/Util/DeclareRuntimeLibcalls/merge_attributes.ll

@@ -0,0 +1,11 @@
+; RUN: opt -S -passes=declare-runtime-libcalls -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
+
+define noundef nofpclass(nan) float @sqrtf(float %x) "foo" {
+  %ret = call float asm "; $0 = sqrt($1)", "=r,r"(float %x)
+  ret float %ret
+}
+
+; FIXME: Individual fields of nofpclass not merged
+; CHECK: define noundef nofpclass(ninf nsub nnorm) float @sqrtf(float %x) [[SQRT_ATTR:#[0-9]+]] {
+
+; CHECK: attributes [[SQRT_ATTR]] = { nocallback nofree nosync nounwind willreturn memory(errnomem: write) "foo" }

llvm/test/Transforms/Util/DeclareRuntimeLibcalls/sincos_stret.ll

@@ -0,0 +1,23 @@
+; RUN: opt -S -passes=declare-runtime-libcalls -mtriple=x86_64-apple-macos10.9 < %s | FileCheck -check-prefixes=CHECK,X64 %s
+; RUN: opt -S -passes=declare-runtime-libcalls -mtriple=arm64-apple-macos10.9 < %s | FileCheck -check-prefixes=CHECK,STRUCT %s
+; RUN: opt -S -passes=declare-runtime-libcalls -mtriple=thumbv7k-apple-watchos2.0 < %s | FileCheck -check-prefixes=CHECK,STRUCT %s
+; RUN: opt -S -passes=declare-runtime-libcalls -mtriple=armv7-apple-ios7 < %s | FileCheck -check-prefix=SRET %s
+; RUN: opt -S -passes=declare-runtime-libcalls -mtriple=thumbv7-apple-ios7 < %s | FileCheck -check-prefix=SRET %s
+
+; RUN: opt -S -passes=declare-runtime-libcalls -mtriple=armv7-apple-ios6 < %s | FileCheck -check-prefix=NONE %s
+; RUN: opt -S -passes=declare-runtime-libcalls -mtriple=x86_64-apple-macos10.8 < %s | FileCheck -check-prefix=NONE %s
+
+; X64: declare <2 x float> @__sincosf_stret(float) [[SINCOS_ATTRS:#[0-9]+]]
+; X64: declare { double, double } @__sincos_stret(double) [[SINCOS_ATTRS:#[0-9]+]]
+
+; STRUCT: declare { float, float } @__sincosf_stret(float) [[SINCOS_ATTRS:#[0-9]+]]
+; STRUCT: declare { double, double } @__sincos_stret(double) [[SINCOS_ATTRS:#[0-9]+]]
+
+; SRET: declare void @__sincosf_stret(ptr sret({ float, float }) align 4, float) [[SINCOS_ATTRS:#[0-9]+]]
+; SRET: declare void @__sincos_stret(ptr sret({ double, double }) align 4, double) [[SINCOS_ATTRS:#[0-9]+]]
+
+; CHECK: attributes [[SINCOS_ATTRS]] = { nocallback nofree nosync nounwind willreturn memory(errnomem: write) }
+; SRET: attributes [[SINCOS_ATTRS]] = { nocallback nofree nosync nounwind willreturn memory(argmem: write, errnomem: write) }
+
+; NONE-NOT: __sincos_stret
+; NONE-NOT: __sincosf_stret

llvm/test/Transforms/Util/DeclareRuntimeLibcalls/wrong_declaration.ll

@@ -0,0 +1,21 @@
+; RUN: opt -S -passes=declare-runtime-libcalls -mtriple=x86_64-apple-macos10.9 < %s | FileCheck %s
+
+; Make sure there is no crash if there are definitions or declarations
+; with the wrong type signature.
+
+; CHECK: define void @sqrtf() {
+define void @sqrtf() {
+  ret void
+}
+
+; CHECK: define float @sqrt(float %0) {
+define float @sqrt(float) {
+  ret float 0.0
+}
+
+; CHECK: declare double @__sincos_stret(double)
+declare double @__sincos_stret(double)
+
+; CHECK: declare { float, float } @__sincosf_stret(float)
+declare { float, float } @__sincosf_stret(float)
+