Do not store "+soft-float" and "+soft-float-abi" target features in function attributes

[olista01]

Summary

These target features are used by the clang driver when targeting ARM and MIPS, but cc1 strips them out and they are not valid backend features. Therefore, we should not store them in the function attributes.

[echristo]

Hi Oliver,

I'm not sure this is the right direction to go here, I've got another patch
in progress to solve this problem and I'll have something tomorrow. Sorry
about the delay.

Thanks!

-eric

[olista01]

Hi Eric,

Are you still working on this? This is still causing a spurious warning from the ARM backend.

Oliver

[echristo]

I am, yes. I have autoupgrade working for both of these to move them to
actual soft float attributes, and I'm dealing with the command line
options/TargetOptions side of things right now.

-eric

[echristo]

I committed r236060 to clang which should solve your immediate problem.

-eric

lib/CodeGen/CGCall.cpp

if (AttrOnCallSite) {
     // TODO: FeaturesAsWritten gets us the features on the command line,
     // for canonicalization purposes we might want to avoid putting features
     // in the target-features set if we know it'll be one of the default
     // features in the backend, e.g. corei7-avx and +avx.
     std::vector<std::string> &Features =
         getTarget().getTargetOpts().FeaturesAsWritten;
     if (!Features.empty()) {
       std::stringstream S;
-      std::copy(Features.begin(), Features.end(),
-                std::ostream_iterator<std::string>(S, ","));
+      // The "+soft-float" and "+soft-float-abi" features are not real target
+      // features, and should not be passed to the backend.
+      std::copy_if(Features.begin(), Features.end(),
+                   std::ostream_iterator<std::string>(S, ","),
+                   [](const std::string& name) {
+                     return (name != "+soft-float") && (name != "+soft-float-abi");
+                   });
       // The drop_back gets rid of the trailing space.
-      FuncAttrs.addAttribute("target-features",
-                             StringRef(S.str()).drop_back(1));
+      if (!S.str().empty())
+        FuncAttrs.addAttribute("target-features", StringRef(S.str()).drop_back(1));
     }
   }
 
   ClangToLLVMArgMapping IRFunctionArgs(getContext(), FI);
 
   QualType RetTy = FI.getReturnType();
   const ABIArgInfo &RetAI = FI.getReturnInfo();
   switch (RetAI.getKind()) {

test/CodeGen/function-target-features.c

 // This test verifies that we produce target-cpu and target-features attributes
 // on functions when they're different from the standard cpu and have written
 // features.
 
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-feature +avx | FileCheck %s -check-prefix=AVX-FEATURE
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-feature +avx | FileCheck %s -check-prefix=AVX-NO-CPU
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-feature +avx512f -target-feature +avx512er | FileCheck %s -check-prefix=TWO-AVX
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-cpu corei7 | FileCheck %s -check-prefix=CORE-CPU
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-cpu corei7 -target-feature +avx | FileCheck %s -check-prefix=CORE-CPU-AND-FEATURES
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-cpu x86-64 | FileCheck %s -check-prefix=X86-64-CPU-NOT
 // RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-cpu corei7-avx -target-feature -avx | FileCheck %s -check-prefix=AVX-MINUS-FEATURE
+// RUN: %clang_cc1 -triple armv7-none-eabi -emit-llvm -o - %s -target-feature +soft-float | FileCheck %s -check-prefix=ARM-SOFT-FLOAT
+// RUN: %clang_cc1 -triple armv7-none-eabi -emit-llvm -o - %s -target-feature +soft-float-abi | FileCheck %s -check-prefix=ARM-SOFT-FLOAT-ABI
 
 void foo() {}
 
 // AVX-FEATURE: "target-features"="+avx"
 // AVX-NO-CPU-NOT: target-cpu
 // TWO-AVX: "target-features"="+avx512f,+avx512er"
 // CORE-CPU: "target-cpu"="corei7"
 // CORE-CPU-AND-FEATURES: "target-cpu"="corei7" "target-features"="+avx"
 // X86-64-CPU-NOT: "target-cpu"
 // AVX-MINUS-FEATURE: "target-features"="-avx"
+// ARM-SOFT-FLOAT-NOT: "target-features"
+// ARM-SOFT-FLOAT-ABI-NOT: "target-features"