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//===---- Mips16HardFloat.cpp for Mips16 Hard Float --------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a pass needed for Mips16 Hard Float
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "mips16-hard-float"
#include "Mips16HardFloat.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include <string>
//
// Return types that matter for hard float are:
// float, double, complex float, and complex double
//
enum FPReturnVariant {
FRet, DRet, CFRet, CDRet, NoFPRet
};
//
// Determine which FP return type this function has
//
static FPReturnVariant whichFPReturnVariant(Type *T) {
switch (T->getTypeID()) {
case Type::FloatTyID:
return FRet;
case Type::DoubleTyID:
return DRet;
case Type::StructTyID:
if (T->getStructNumElements() != 2)
break;
if ((T->getContainedType(0)->isFloatTy()) &&
(T->getContainedType(1)->isFloatTy()))
return CFRet;
if ((T->getContainedType(0)->isDoubleTy()) &&
(T->getContainedType(1)->isDoubleTy()))
return CDRet;
break;
default:
break;
}
return NoFPRet;
}
//
// Returns of float, double and complex need to be handled with a helper
// function. The "AndCal" part is coming in a later patch.
//
static bool fixupFPReturnAndCall
(Function &F, Module *M, const MipsSubtarget &Subtarget) {
bool Modified = false;
LLVMContext &C = M->getContext();
Type *MyVoid = Type::getVoidTy(C);
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
for (BasicBlock::iterator I = BB->begin(), E = BB->end();
I != E; ++I) {
Instruction &Inst = *I;
if (const ReturnInst *RI = dyn_cast<ReturnInst>(I)) {
Value *RVal = RI->getReturnValue();
if (!RVal) continue;
//
// If there is a return value and it needs a helper function,
// figure out which one and add a call before the actual
// return to this helper. The purpose of the helper is to move
// floating point values from their soft float return mapping to
// where they would have been mapped to in floating point registers.
//
Type *T = RVal->getType();
FPReturnVariant RV = whichFPReturnVariant(T);
if (RV == NoFPRet) continue;
static const char* Helper[NoFPRet] =
{"__mips16_ret_sf", "__mips16_ret_df", "__mips16_ret_sc",
"__mips16_ret_dc"};
const char *Name = Helper[RV];
AttributeSet A;
Value *Params[] = {RVal};
Modified = true;
//
// These helper functions have a different calling ABI so
// this __Mips16RetHelper indicates that so that later
// during call setup, the proper call lowering to the helper
// functions will take place.
//
A = A.addAttribute(C, AttributeSet::FunctionIndex,
"__Mips16RetHelper");
A = A.addAttribute(C, AttributeSet::FunctionIndex,
Attribute::ReadNone);
Value *F = (M->getOrInsertFunction(Name, A, MyVoid, T, NULL));
CallInst::Create(F, Params, "", &Inst );
}
}
return Modified;
}
namespace llvm {
//
// This pass only makes sense when the underlying chip has floating point but
// we are compiling as mips16.
// For all mips16 functions (that are not stubs we have already generated), or
// declared via attributes as nomips16, we must:
// 1) fixup all returns of float, double, single and double complex
// by calling a helper function before the actual return.
// 2) generate helper functions (stubs) that can be called by mips32 functions
// that will move parameters passed normally passed in floating point
// registers the soft float equivalents. (Coming in a later patch).
// 3) in the case of static relocation, generate helper functions so that
// mips16 functions can call extern functions of unknown type (mips16 or
// mips32). (Coming in a later patch).
// 4) TBD. For pic, calls to extern functions of unknown type are handled by
// predefined helper functions in libc but this work is currently done
// during call lowering but it should be moved here in the future.
//
bool Mips16HardFloat::runOnModule(Module &M) {
DEBUG(errs() << "Run on Module Mips16HardFloat\n");
bool Modified = false;
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
if (F->isDeclaration() || F->hasFnAttribute("mips16_fp_stub") ||
F->hasFnAttribute("nomips16")) continue;
Modified |= fixupFPReturnAndCall(*F, &M, Subtarget);
}
return Modified;
}
char Mips16HardFloat::ID = 0;
}
ModulePass *llvm::createMips16HardFloat(MipsTargetMachine &TM) {
return new Mips16HardFloat(TM);
}
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