Set local_unnamed_addr for new library function declarations in InjectTLIMappings.

[tianqing]

Summary

When InjectTLIMappings constructs the list of vector functions for VFABI attribute, it tries to find each of the functions in the module. If it's absent, a new function declaration is added. In this case, we know the newly added vector function is not used by the original translation unit. It's address is also not used, thus it's good to mark its address insignificant at least at module level.

[fhahn]

Please update the description of the patch with a motivation for the fix and why it is the right thing to do. This will make the change easier to review.

[tianqing]

Fix typos.

[tianqing]

Ping.

llvm/lib/Transforms/Utils/InjectTLIMappings.cpp

static void addVariantDeclaration(CallInst &CI, const ElementCount &VF,
   FunctionType *FTy = FunctionType::get(RetTy, Tys, /*isVarArg=*/false);
   Function *VectorF =
       Function::Create(FTy, Function::ExternalLinkage, VFName, M);
   VectorF->copyAttributesFrom(CI.getCalledFunction());
   ++NumVFDeclAdded;
   LLVM_DEBUG(dbgs() << DEBUG_TYPE << ": Added to the module: `" << VFName
                     << "` of type " << *(VectorF->getType()) << "\n");
 
+  // Since we are adding a declaration we know the source code doesn't use the
+  // function directly and it's address can't be significant. Make sure the
+  // declaration is marked local_unnamed_addr, otherwise the compiler may emit
+  // unnecessary symbols for unused functions in some cases like LTO with
+  // .addrsig section enabled.
+  if (VectorF->getUnnamedAddr() == GlobalValue::UnnamedAddr::None)
+    VectorF->setUnnamedAddr(GlobalValue::UnnamedAddr::Local);
+
   // Make function declaration (without a body) "sticky" in the IR by
   // listing it in the @llvm.compiler.used intrinsic.
   assert(!VectorF->size() && "VFABI attribute requires `@llvm.compiler.used` "
                              "only on declarations.");
   appendToCompilerUsed(*M, {VectorF});
   LLVM_DEBUG(dbgs() << DEBUG_TYPE << ": Adding `" << VFName
                     << "` to `@llvm.compiler.used`.\n");
   ++NumCompUsedAdded;

llvm/test/Transforms/Util/add-TLI-mappings-unnamed-addr.ll

+; Check that InjectTLIMappings adds local_unnamed_addr to newly-added function
+; declarations, and not to existing ones.
+; RUN: opt -vector-library=LIBMVEC-X86 -inject-tli-mappings        -S < %s | FileCheck %s
+; RUN: opt -vector-library=LIBMVEC-X86 -passes=inject-tli-mappings -S < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK-LABEL: @llvm.compiler.used = appending global
+; CHECK: [1 x i8*] [
+; CHECK:   i8* bitcast (<4 x double> (<4 x double>)* @_ZGVdN4v_sin to i8*)
+; CHECK: ], section "llvm.metadata"
+
+define double @sin_f64(double %in) {
+; CHECK-LABEL: @sin_f64(
+; CHECK:       call double @sin(double %{{.*}}) #[[SIN:[0-9]+]]
+  %call = tail call double @sin(double %in)
+  ret double %call
+}
+
+; CHECK: declare double @sin(double)
+declare double @sin(double) #0
+
+; CHECK: declare <2 x double> @_ZGVbN2v_sin(<2 x double>)
+; CHECK-NOT: local_unnamed_addr
+declare <2 x double> @_ZGVbN2v_sin(<2 x double>)
+; CHECK: declare <4 x double> @_ZGVdN4v_sin(<4 x double>) local_unnamed_addr
+
+attributes #0 = { nounwind readnone }
+
+; CHECK:      attributes #[[SIN]] = { "vector-function-abi-variant"=
+; CHECK-SAME:   "_ZGV_LLVM_N2v_sin(_ZGVbN2v_sin),
+; CHECK-SAME:   _ZGV_LLVM_N4v_sin(_ZGVdN4v_sin)" }

llvm/test/Transforms/Util/add-TLI-mappings.ll

 ; ACCELERATE:   call float @llvm.log10.f32(float %{{.*}}) #[[LOG10:[0-9]+]]
 ; No mapping of "llvm.log10.f32" to a vector function for SVML.
 ; SVML-NOT:     _ZGV_LLVM_{{.*}}_llvm.log10.f32({{.*}})
 ; LIBMVEC-X86-NOT: _ZGV_LLVM_{{.*}}_llvm.log10.f32({{.*}})
   %call = tail call float @llvm.log10.f32(float %in)
   ret float %call
 }
 
+; SVML: declare <2 x double> @__svml_sin2(<2 x double>) local_unnamed_addr
+; SVML: declare <4 x double> @__svml_sin4(<4 x double>) local_unnamed_addr
+; SVML: declare <8 x double> @__svml_sin8(<8 x double>) local_unnamed_addr
+; SVML: declare <4 x float> @__svml_log10f4(<4 x float>) local_unnamed_addr
+; SVML: declare <8 x float> @__svml_log10f8(<8 x float>) local_unnamed_addr
+; SVML: declare <16 x float> @__svml_log10f16(<16 x float>) local_unnamed_addr
+; MASSV: declare <2 x double> @__sind2_P8(<2 x double>) local_unnamed_addr
+; MASSV: declare <4 x float> @__log10f4_P8(<4 x float>) local_unnamed_addr
+; ACCELERATE: declare <4 x float> @vlog10f(<4 x float>) local_unnamed_addr
+; LIBMVEC-X86: declare <2 x double> @_ZGVbN2v_sin(<2 x double>) local_unnamed_addr
+; LIBMVEC-X86: declare <4 x double> @_ZGVdN4v_sin(<4 x double>) local_unnamed_addr
+
 declare float @llvm.log10.f32(float) #0
 attributes #0 = { nounwind readnone }
 
 ; SVML:      attributes #[[SIN]] = { "vector-function-abi-variant"=
 ; SVML-SAME:   "_ZGV_LLVM_N2v_sin(__svml_sin2),
 ; SVML-SAME:   _ZGV_LLVM_N4v_sin(__svml_sin4),
 ; SVML-SAME:   _ZGV_LLVM_N8v_sin(__svml_sin8)" }