[Modules] Add 'freestanding' to the 'requires-declaration' feature-list.

[eladcohen]

Summary

This adds support for modules that require (non-)freestanding environment such as the compiler builtin mm_malloc submodule.

[rsmith]

Makes sense to me. I imagine this would also be useful for libc++.

lib/Headers/module.modulemap

66 ↗

(On Diff #69239)

Are there more parts of the intrinsics modules to which this should be applied?

[eladcohen]

lib/Headers/module.modulemap

66 ↗

(On Diff #69239)

Not that I'm aware of. A "STDC_HOSTED" grep on the intrinsics modules header files didn't find anything other than mm_malloc.h.

[eladcohen]

Thanks Richard, committed r280613.

cfe/trunk/docs/Modules.rst

blocks
   The "blocks" language feature is available.
 
 cplusplus
   C++ support is available.
 
 cplusplus11
   C++11 support is available.
 
+freestanding
+  A freestanding environment is available.
+
 gnuinlineasm
   GNU inline ASM is available.
 
 objc
   Objective-C support is available.
 
 objc_arc
   Objective-C Automatic Reference Counting (ARC) is available

cfe/trunk/lib/Basic/Module.cpp

 /// language options has the given feature.
 static bool hasFeature(StringRef Feature, const LangOptions &LangOpts,
                        const TargetInfo &Target) {
   bool HasFeature = llvm::StringSwitch<bool>(Feature)
                         .Case("altivec", LangOpts.AltiVec)
                         .Case("blocks", LangOpts.Blocks)
                         .Case("cplusplus", LangOpts.CPlusPlus)
                         .Case("cplusplus11", LangOpts.CPlusPlus11)
+                        .Case("freestanding", LangOpts.Freestanding)
                         .Case("gnuinlineasm", LangOpts.GNUAsm)
                         .Case("objc", LangOpts.ObjC1)
                         .Case("objc_arc", LangOpts.ObjCAutoRefCount)
                         .Case("opencl", LangOpts.OpenCL)
                         .Case("tls", Target.isTLSSupported())
                         .Case("zvector", LangOpts.ZVector)
                         .Default(Target.hasFeature(Feature));
   if (!HasFeature)

cfe/trunk/lib/Headers/module.modulemap

explicit module intel {
     textual header "bmiintrin.h"
     textual header "bmi2intrin.h"
     textual header "lzcntintrin.h"
     textual header "xopintrin.h"
     textual header "fma4intrin.h"
     textual header "mwaitxintrin.h"
 
     explicit module mm_malloc {
+      requires !freestanding
       header "mm_malloc.h"
       export * // note: for <stdlib.h> dependency
     }
 
     explicit module cpuid {
       requires gnuinlineasm
       header "cpuid.h"
     }

cfe/trunk/test/Modules/compiler_builtins_x86.c

+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fsyntax-only -fmodules -fimplicit-module-maps -fmodules-cache-path=%t %s -verify -ffreestanding
+// expected-no-diagnostics
+
+#include<x86intrin.h>
+