Added -float-abi and auto-detection logic for ARM.

Even though this argument design conflates two separate concepts
(ABI and hardware/software implementation), I chose to go
with it since users are liekly know it from GCC and the
combination of softloat operations with hardfloat ABI makes
no sense.

I didn't implement it for old LLVM versions, as ARM EABI
exception handling requires LLVM 3.3+ anyway, without which
LDC would be useless anyway.

driver/cl_options.cpp

@@ -310,6 +310,16 @@ cl::opt<llvm::CodeModel::Model> mCodeModel("code-model",
         clEnumValN(llvm::CodeModel::Large, "large", "Large code model"),
         clEnumValEnd));
 
+cl::opt<FloatABI::Type> mFloatABI("float-abi",
+    cl::desc("ABI/operations to use for floating-point types:"),
+    cl::init(FloatABI::Default),
+    cl::values(
+        clEnumValN(FloatABI::Default, "default", "Target default floating-point ABI"),
+        clEnumValN(FloatABI::Soft, "soft", "Software floating-point ABI and operations"),
+        clEnumValN(FloatABI::SoftFP, "softfp", "Soft-float ABI, but hardware floating-point instructions"),
+        clEnumValN(FloatABI::Hard, "hard", "Hardware floating-point ABI and instructions"),
+        clEnumValEnd));
+
 static cl::opt<bool, true, FlagParser> asserts("asserts",
     cl::desc("(*) Enable assertions"),
     cl::value_desc("bool"),

driver/cl_options.h

@@ -16,6 +16,7 @@
 #define LDC_DRIVER_CL_OPTIONS_H
 
 #include "mars.h"
+#include "driver/target.h"
 #include "llvm/Support/CodeGen.h"
 #include "llvm/Support/CommandLine.h"
 #include <deque>
@@ -60,6 +61,7 @@ namespace opts {
     extern cl::opt<std::string> mTargetTriple;
     extern cl::opt<llvm::Reloc::Model> mRelocModel;
     extern cl::opt<llvm::CodeModel::Model> mCodeModel;
+    extern cl::opt<FloatABI::Type> mFloatABI;
     extern cl::opt<bool, true> singleObj;
     extern cl::opt<bool> linkonceTemplates;
 

driver/main.cpp

@@ -459,8 +459,9 @@ int main(int argc, char** argv)
     if (global.errors)
         fatal();
 
-    gTargetMachine = createTargetMachine(mTargetTriple, mArch, mCPU, mAttrs, bitness,
+    gTargetMachine = createTargetMachine(mTargetTriple, mArch, mCPU, mAttrs,
-        mRelocModel, mCodeModel, codeGenOptLevel(), global.params.symdebug);
+        bitness, mFloatABI, mRelocModel, mCodeModel, codeGenOptLevel(),
+        global.params.symdebug);
     global.params.targetTriple = llvm::Triple(gTargetMachine->getTargetTriple());
 
 #if LDC_LLVM_VER >= 302

driver/target.cpp

@@ -7,13 +7,15 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// Note: The target CPU detection logic has been adapted from Clang
+// Note: The target CPU and FP ABI detection logic has been adapted from Clang
-// (lib/Driver/Tools.cpp).
+// (Tools.cpp and ToolChain.cpp in lib/Driver, the latter seems to have the
+// more up-to-date version).
 //
 //===----------------------------------------------------------------------===//
 
 #include "driver/target.h"
 #include "gen/llvmcompat.h"
+#include "llvm/ADT/StringSwitch.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/MC/SubtargetFeature.h"
 #include "llvm/Support/Host.h"
@@ -23,7 +25,6 @@
 #include "llvm/Target/TargetOptions.h"
 #include "mars.h"
 
-
 static std::string getX86TargetCPU(std::string arch,
     const llvm::Triple &triple)
 {
@@ -74,12 +75,130 @@ static std::string getX86TargetCPU(std::string arch,
 }
 
 
+static const char *getLLVMArchSuffixForARM(llvm::StringRef CPU)
+{
+    return llvm::StringSwitch<const char *>(CPU)
+        .Cases("arm7tdmi", "arm7tdmi-s", "arm710t", "v4t")
+        .Cases("arm720t", "arm9", "arm9tdmi", "v4t")
+        .Cases("arm920", "arm920t", "arm922t", "v4t")
+        .Cases("arm940t", "ep9312","v4t")
+        .Cases("arm10tdmi",  "arm1020t", "v5")
+        .Cases("arm9e",  "arm926ej-s",  "arm946e-s", "v5e")
+        .Cases("arm966e-s",  "arm968e-s",  "arm10e", "v5e")
+        .Cases("arm1020e",  "arm1022e",  "xscale", "iwmmxt", "v5e")
+        .Cases("arm1136j-s",  "arm1136jf-s",  "arm1176jz-s", "v6")
+        .Cases("arm1176jzf-s",  "mpcorenovfp",  "mpcore", "v6")
+        .Cases("arm1156t2-s",  "arm1156t2f-s", "v6t2")
+        .Cases("cortex-a5", "cortex-a7", "cortex-a8", "v7")
+        .Cases("cortex-a9", "cortex-a15", "v7")
+        .Case("cortex-r5", "v7r")
+        .Case("cortex-m0", "v6m")
+        .Case("cortex-m3", "v7m")
+        .Case("cortex-m4", "v7em")
+        .Case("cortex-a9-mp", "v7f")
+        .Case("swift", "v7s")
+        .Default("");
+}
+
+static std::string getARMTargetCPU(std::string arch, const llvm::Triple &triple)
+{
+    // FIXME: Warn on inconsistent use of -mcpu and -march.
+
+    llvm::StringRef MArch;
+    if (!arch.empty()) {
+        // Otherwise, if we have -march= choose the base CPU for that arch.
+        MArch = arch;
+    } else {
+        // Otherwise, use the Arch from the triple.
+        MArch = triple.getArchName();
+    }
+
+    // Handle -march=native.
+    std::string NativeMArch;
+    if (MArch == "native") {
+        std::string CPU = llvm::sys::getHostCPUName();
+        if (CPU != "generic") {
+            // Translate the native cpu into the architecture. The switch below will
+            // then chose the minimum cpu for that arch.
+            NativeMArch = std::string("arm") + getLLVMArchSuffixForARM(CPU);
+            MArch = NativeMArch;
+        }
+    }
+
+    return llvm::StringSwitch<const char *>(MArch)
+        .Cases("armv2", "armv2a","arm2")
+        .Case("armv3", "arm6")
+        .Case("armv3m", "arm7m")
+        .Cases("armv4", "armv4t", "arm7tdmi")
+        .Cases("armv5", "armv5t", "arm10tdmi")
+        .Cases("armv5e", "armv5te", "arm1026ejs")
+        .Case("armv5tej", "arm926ej-s")
+        .Cases("armv6", "armv6k", "arm1136jf-s")
+        .Case("armv6j", "arm1136j-s")
+        .Cases("armv6z", "armv6zk", "arm1176jzf-s")
+        .Case("armv6t2", "arm1156t2-s")
+        .Cases("armv6m", "armv6-m", "cortex-m0")
+        .Cases("armv7", "armv7a", "armv7-a", "cortex-a8")
+        .Cases("armv7l", "armv7-l", "cortex-a8")
+        .Cases("armv7f", "armv7-f", "cortex-a9-mp")
+        .Cases("armv7s", "armv7-s", "swift")
+        .Cases("armv7r", "armv7-r", "cortex-r4")
+        .Cases("armv7m", "armv7-m", "cortex-m3")
+        .Cases("armv7em", "armv7e-m", "cortex-m4")
+        .Case("ep9312", "ep9312")
+        .Case("iwmmxt", "iwmmxt")
+        .Case("xscale", "xscale")
+        // If all else failed, return the most base CPU LLVM supports.
+        .Default("arm7tdmi");
+}
+
+static FloatABI::Type getARMFloatABI(const llvm::Triple &triple,
+    const char* llvmArchSuffix)
+{
+    switch (triple.getOS()) {
+    case llvm::Triple::Darwin:
+    case llvm::Triple::MacOSX:
+    case llvm::Triple::IOS: {
+        // Darwin defaults to "softfp" for v6 and v7.
+        if (llvm::StringRef(llvmArchSuffix).startswith("v6") ||
+            llvm::StringRef(llvmArchSuffix).startswith("v7"))
+            return FloatABI::SoftFP;
+        return FloatABI::Soft;
+    }
+
+    case llvm::Triple::FreeBSD:
+        // FreeBSD defaults to soft float
+        return FloatABI::Soft;
+
+    default:
+        switch(triple.getEnvironment()) {
+        case llvm::Triple::GNUEABIHF:
+            return FloatABI::Hard;
+        case llvm::Triple::GNUEABI:
+            return FloatABI::SoftFP;
+        case llvm::Triple::EABI:
+            // EABI is always AAPCS, and if it was not marked 'hard', it's softfp
+            return FloatABI::SoftFP;
+        case llvm::Triple::Android: {
+            if (llvm::StringRef(llvmArchSuffix).startswith("v7"))
+                return FloatABI::SoftFP;
+            return FloatABI::Soft;
+        }
+        default:
+            // Assume "soft", but warn the user we are guessing.
+            return FloatABI::SoftFP;
+        }
+    }
+}
+
+
 llvm::TargetMachine* createTargetMachine(
     std::string targetTriple,
     std::string arch,
     std::string cpu,
     std::vector<std::string> attrs,
     ExplicitBitness::Type bitness,
+    FloatABI::Type floatABI,
     llvm::Reloc::Model relocModel,
     llvm::CodeModel::Model codeModel,
     llvm::CodeGenOpt::Level codeGenOptLevel,
@@ -159,10 +278,16 @@ llvm::TargetMachine* createTargetMachine(
     // to default to "generic").
     if (cpu.empty())
     {
-        if (triple.getArch() == llvm::Triple::x86_64 ||
+        switch (triple.getArch())
-            triple.getArch() == llvm::Triple::x86)
         {
+        default: break;
+        case llvm::Triple::x86:
+        case llvm::Triple::x86_64:
             cpu = getX86TargetCPU(arch, triple);
+            break;
+        case llvm::Triple::arm:
+            cpu = getARMTargetCPU(arch, triple);
+            break;
         }
     }
 
@@ -176,8 +301,25 @@ llvm::TargetMachine* createTargetMachine(
         FeaturesStr = Features.getString();
     }
 
+    if (floatABI == FloatABI::Default)
+    {
+        switch (triple.getArch())
+        {
+        default: // X86, ...
+            floatABI = FloatABI::Hard;
+            break;
+        case llvm::Triple::arm:
+            floatABI = getARMFloatABI(triple, getLLVMArchSuffixForARM(cpu));
+            break;
+        case llvm::Triple::thumb:
+            floatABI = FloatABI::Soft;
+            break;
+        }
+    }
+
 #if LDC_LLVM_VER == 300
     llvm::NoFramePointerElim = genDebugInfo;
+    // FIXME: Handle floating-point ABI.
 
     return theTarget->createTargetMachine(triple.str(), cpu, FeaturesStr,
         relocModel, codeModel);
@@ -185,6 +327,23 @@ llvm::TargetMachine* createTargetMachine(
     llvm::TargetOptions targetOptions;
     targetOptions.NoFramePointerElim = genDebugInfo;
 
+    switch (floatABI)
+    {
+    default: llvm_unreachable("Floating point ABI type unknown.");
+    case FloatABI::Soft:
+        targetOptions.UseSoftFloat = true;
+        targetOptions.FloatABIType = llvm::FloatABI::Soft;
+        break;
+    case FloatABI::SoftFP:
+        targetOptions.UseSoftFloat = false;
+        targetOptions.FloatABIType = llvm::FloatABI::Soft;
+        break;
+    case FloatABI::Hard:
+        targetOptions.UseSoftFloat = false;
+        targetOptions.FloatABIType = llvm::FloatABI::Hard;
+        break;
+    }
+
     return theTarget->createTargetMachine(
         triple.str(),
         cpu,

driver/target.h

@@ -30,6 +30,15 @@ namespace ExplicitBitness {
     };
 }
 
+namespace FloatABI {
+    enum Type {
+        Default,
+        Soft,
+        SoftFP,
+        Hard
+    };
+}
+
 namespace llvm { class TargetMachine; }
 
 /**
@@ -44,6 +53,7 @@ llvm::TargetMachine* createTargetMachine(
     std::string cpu,
     std::vector<std::string> attrs,
     ExplicitBitness::Type bitness,
+    FloatABI::Type floatABI,
     llvm::Reloc::Model relocModel,
     llvm::CodeModel::Model codeModel,
     llvm::CodeGenOpt::Level codeGenOptLevel,