[llvm-commits] CVS: llvm/lib/Target/CBackend/Writer.cpp
Chris Lattner
lattner at cs.uiuc.edu
Tue May 23 16:40:00 PDT 2006
Changes in directory llvm/lib/Target/CBackend:
Writer.cpp updated: 1.260 -> 1.261
---
Log message:
Print struct return functions and calls as actually returning the hidden
argument struct pointer, enabling ABI compatibility for the CBE with
platforms with strange struct-return ABIs. This fixes 252.eon and
CoyoteBench/fftbench on Darwin/X86 among other things.
---
Diffs of the changes: (+171 -75)
Writer.cpp | 246 ++++++++++++++++++++++++++++++++++++++++++-------------------
1 files changed, 171 insertions(+), 75 deletions(-)
Index: llvm/lib/Target/CBackend/Writer.cpp
diff -u llvm/lib/Target/CBackend/Writer.cpp:1.260 llvm/lib/Target/CBackend/Writer.cpp:1.261
--- llvm/lib/Target/CBackend/Writer.cpp:1.260 Mon Apr 17 12:55:40 2006
+++ llvm/lib/Target/CBackend/Writer.cpp Tue May 23 18:39:48 2006
@@ -13,6 +13,7 @@
//===----------------------------------------------------------------------===//
#include "CTargetMachine.h"
+#include "llvm/CallingConv.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
@@ -115,6 +116,9 @@
const std::string &VariableName = "",
bool IgnoreName = false);
+ void printStructReturnPointerFunctionType(std::ostream &Out,
+ const PointerType *Ty);
+
void writeOperand(Value *Operand);
void writeOperandInternal(Value *Operand);
@@ -298,6 +302,35 @@
return Changed;
}
+/// printStructReturnPointerFunctionType - This is like printType for a struct
+/// return type, except, instead of printing the type as void (*)(Struct*, ...)
+/// print it as "Struct (*)(...)", for struct return functions.
+void CWriter::printStructReturnPointerFunctionType(std::ostream &Out,
+ const PointerType *TheTy) {
+ const FunctionType *FTy = cast<FunctionType>(TheTy->getElementType());
+ std::stringstream FunctionInnards;
+ FunctionInnards << " (*) (";
+ bool PrintedType = false;
+
+ FunctionType::param_iterator I = FTy->param_begin(), E = FTy->param_end();
+ const Type *RetTy = cast<PointerType>(I->get())->getElementType();
+ for (++I; I != E; ++I) {
+ if (PrintedType)
+ FunctionInnards << ", ";
+ printType(FunctionInnards, *I, "");
+ PrintedType = true;
+ }
+ if (FTy->isVarArg()) {
+ if (PrintedType)
+ FunctionInnards << ", ...";
+ } else if (!PrintedType) {
+ FunctionInnards << "void";
+ }
+ FunctionInnards << ')';
+ std::string tstr = FunctionInnards.str();
+ printType(Out, RetTy, tstr);
+}
+
// Pass the Type* and the variable name and this prints out the variable
// declaration.
@@ -332,24 +365,24 @@
switch (Ty->getTypeID()) {
case Type::FunctionTyID: {
- const FunctionType *MTy = cast<FunctionType>(Ty);
+ const FunctionType *FTy = cast<FunctionType>(Ty);
std::stringstream FunctionInnards;
FunctionInnards << " (" << NameSoFar << ") (";
- for (FunctionType::param_iterator I = MTy->param_begin(),
- E = MTy->param_end(); I != E; ++I) {
- if (I != MTy->param_begin())
+ for (FunctionType::param_iterator I = FTy->param_begin(),
+ E = FTy->param_end(); I != E; ++I) {
+ if (I != FTy->param_begin())
FunctionInnards << ", ";
printType(FunctionInnards, *I, "");
}
- if (MTy->isVarArg()) {
- if (MTy->getNumParams())
+ if (FTy->isVarArg()) {
+ if (FTy->getNumParams())
FunctionInnards << ", ...";
- } else if (!MTy->getNumParams()) {
+ } else if (!FTy->getNumParams()) {
FunctionInnards << "void";
}
FunctionInnards << ')';
std::string tstr = FunctionInnards.str();
- printType(Out, MTy->getReturnType(), tstr);
+ printType(Out, FTy->getReturnType(), tstr);
return Out;
}
case Type::StructTyID: {
@@ -1223,6 +1256,9 @@
}
void CWriter::printFunctionSignature(const Function *F, bool Prototype) {
+ /// isCStructReturn - Should this function actually return a struct by-value?
+ bool isCStructReturn = F->getCallingConv() == CallingConv::CSRet;
+
if (F->hasInternalLinkage()) Out << "static ";
// Loop over the arguments, printing them...
@@ -1233,55 +1269,97 @@
// Print out the name...
FunctionInnards << Mang->getValueName(F) << '(';
+ bool PrintedArg = false;
if (!F->isExternal()) {
if (!F->arg_empty()) {
+ Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
+
+ // If this is a struct-return function, don't print the hidden
+ // struct-return argument.
+ if (isCStructReturn) {
+ assert(I != E && "Invalid struct return function!");
+ ++I;
+ }
+
std::string ArgName;
- if (F->arg_begin()->hasName() || !Prototype)
- ArgName = Mang->getValueName(F->arg_begin());
- printType(FunctionInnards, F->arg_begin()->getType(), ArgName);
- for (Function::const_arg_iterator I = ++F->arg_begin(), E = F->arg_end();
- I != E; ++I) {
- FunctionInnards << ", ";
+ for (; I != E; ++I) {
+ if (PrintedArg) FunctionInnards << ", ";
if (I->hasName() || !Prototype)
ArgName = Mang->getValueName(I);
else
ArgName = "";
printType(FunctionInnards, I->getType(), ArgName);
+ PrintedArg = true;
}
}
} else {
- // Loop over the arguments, printing them...
- for (FunctionType::param_iterator I = FT->param_begin(),
- E = FT->param_end(); I != E; ++I) {
- if (I != FT->param_begin()) FunctionInnards << ", ";
+ // Loop over the arguments, printing them.
+ FunctionType::param_iterator I = FT->param_begin(), E = FT->param_end();
+
+ // If this is a struct-return function, don't print the hidden
+ // struct-return argument.
+ if (isCStructReturn) {
+ assert(I != E && "Invalid struct return function!");
+ ++I;
+ }
+
+ for (; I != E; ++I) {
+ if (PrintedArg) FunctionInnards << ", ";
printType(FunctionInnards, *I);
+ PrintedArg = true;
}
}
// Finish printing arguments... if this is a vararg function, print the ...,
// unless there are no known types, in which case, we just emit ().
//
- if (FT->isVarArg() && FT->getNumParams()) {
- if (FT->getNumParams()) FunctionInnards << ", ";
+ if (FT->isVarArg() && PrintedArg) {
+ if (PrintedArg) FunctionInnards << ", ";
FunctionInnards << "..."; // Output varargs portion of signature!
- } else if (!FT->isVarArg() && FT->getNumParams() == 0) {
+ } else if (!FT->isVarArg() && !PrintedArg) {
FunctionInnards << "void"; // ret() -> ret(void) in C.
}
FunctionInnards << ')';
- // Print out the return type and the entire signature for that matter
- printType(Out, F->getReturnType(), FunctionInnards.str());
+
+ // Get the return tpe for the function.
+ const Type *RetTy;
+ if (!isCStructReturn)
+ RetTy = F->getReturnType();
+ else {
+ // If this is a struct-return function, print the struct-return type.
+ RetTy = cast<PointerType>(FT->getParamType(0))->getElementType();
+ }
+
+ // Print out the return type and the signature built above.
+ printType(Out, RetTy, FunctionInnards.str());
}
void CWriter::printFunction(Function &F) {
printFunctionSignature(&F, false);
Out << " {\n";
+
+ // If this is a struct return function, handle the result with magic.
+ if (F.getCallingConv() == CallingConv::CSRet) {
+ const Type *StructTy =
+ cast<PointerType>(F.arg_begin()->getType())->getElementType();
+ Out << " ";
+ printType(Out, StructTy, "StructReturn");
+ Out << "; /* Struct return temporary */\n";
+
+ Out << " ";
+ printType(Out, F.arg_begin()->getType(), Mang->getValueName(F.arg_begin()));
+ Out << " = &StructReturn;\n";
+ }
+ bool PrintedVar = false;
+
// print local variable information for the function
for (inst_iterator I = inst_begin(&F), E = inst_end(&F); I != E; ++I)
if (const AllocaInst *AI = isDirectAlloca(&*I)) {
Out << " ";
printType(Out, AI->getAllocatedType(), Mang->getValueName(AI));
Out << "; /* Address-exposed local */\n";
+ PrintedVar = true;
} else if (I->getType() != Type::VoidTy && !isInlinableInst(*I)) {
Out << " ";
printType(Out, I->getType(), Mang->getValueName(&*I));
@@ -1293,9 +1371,11 @@
Mang->getValueName(&*I)+"__PHI_TEMPORARY");
Out << ";\n";
}
+ PrintedVar = true;
}
- Out << '\n';
+ if (PrintedVar)
+ Out << '\n';
if (F.hasExternalLinkage() && F.getName() == "main")
Out << " CODE_FOR_MAIN();\n";
@@ -1366,6 +1446,12 @@
// necessary because we use the instruction classes as opaque types...
//
void CWriter::visitReturnInst(ReturnInst &I) {
+ // If this is a struct return function, return the temporary struct.
+ if (I.getParent()->getParent()->getCallingConv() == CallingConv::CSRet) {
+ Out << " return StructReturn;\n";
+ return;
+ }
+
// Don't output a void return if this is the last basic block in the function
if (I.getNumOperands() == 0 &&
&*--I.getParent()->getParent()->end() == I.getParent() &&
@@ -1729,70 +1815,80 @@
Value *Callee = I.getCalledValue();
- // GCC is really a PITA. It does not permit codegening casts of functions to
- // function pointers if they are in a call (it generates a trap instruction
- // instead!). We work around this by inserting a cast to void* in between the
- // function and the function pointer cast. Unfortunately, we can't just form
- // the constant expression here, because the folder will immediately nuke it.
- //
- // Note finally, that this is completely unsafe. ANSI C does not guarantee
- // that void* and function pointers have the same size. :( To deal with this
- // in the common case, we handle casts where the number of arguments passed
- // match exactly.
- //
+ // If this is a call to a struct-return function, assign to the first
+ // parameter instead of passing it to the call.
+ bool isStructRet = I.getCallingConv() == CallingConv::CSRet;
+ if (isStructRet) {
+ Out << "*(";
+ writeOperand(I.getOperand(1));
+ Out << ") = ";
+ }
+
if (I.isTailCall()) Out << " /*tail*/ ";
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Callee))
- if (CE->getOpcode() == Instruction::Cast)
- if (Function *RF = dyn_cast<Function>(CE->getOperand(0))) {
- const FunctionType *RFTy = RF->getFunctionType();
- if (RFTy->getNumParams() == I.getNumOperands()-1) {
- // If the call site expects a value, and the actual callee doesn't
- // provide one, return 0.
- if (I.getType() != Type::VoidTy &&
- RFTy->getReturnType() == Type::VoidTy)
- Out << "0 /*actual callee doesn't return value*/; ";
- Callee = RF;
- } else {
- // Ok, just cast the pointer type.
- Out << "((";
- printType(Out, CE->getType());
- Out << ")(void*)";
- printConstant(RF);
- Out << ')';
- WroteCallee = true;
- }
- }
const PointerType *PTy = cast<PointerType>(Callee->getType());
const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
- const Type *RetTy = FTy->getReturnType();
+
+ if (!WroteCallee) {
+ // If this is an indirect call to a struct return function, we need to cast
+ // the pointer.
+ bool NeedsCast = isStructRet && !isa<Function>(Callee);
+
+ // GCC is a real PITA. It does not permit codegening casts of functions to
+ // function pointers if they are in a call (it generates a trap instruction
+ // instead!). We work around this by inserting a cast to void* in between
+ // the function and the function pointer cast. Unfortunately, we can't just
+ // form the constant expression here, because the folder will immediately
+ // nuke it.
+ //
+ // Note finally, that this is completely unsafe. ANSI C does not guarantee
+ // that void* and function pointers have the same size. :( To deal with this
+ // in the common case, we handle casts where the number of arguments passed
+ // match exactly.
+ //
+ if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Callee))
+ if (CE->getOpcode() == Instruction::Cast)
+ if (Function *RF = dyn_cast<Function>(CE->getOperand(0))) {
+ NeedsCast = true;
+ Callee = RF;
+ }
+
+ if (NeedsCast) {
+ // Ok, just cast the pointer type.
+ Out << "((";
+ if (!isStructRet)
+ printType(Out, I.getCalledValue()->getType());
+ else
+ printStructReturnPointerFunctionType(Out,
+ cast<PointerType>(I.getCalledValue()->getType()));
+ Out << ")(void*)";
+ }
+ writeOperand(Callee);
+ if (NeedsCast) Out << ')';
+ }
- if (!WroteCallee) writeOperand(Callee);
Out << '(';
unsigned NumDeclaredParams = FTy->getNumParams();
- if (I.getNumOperands() != 1) {
- CallSite::arg_iterator AI = I.op_begin()+1, AE = I.op_end();
- if (NumDeclaredParams && (*AI)->getType() != FTy->getParamType(0)) {
+ CallSite::arg_iterator AI = I.op_begin()+1, AE = I.op_end();
+ unsigned ArgNo = 0;
+ if (isStructRet) { // Skip struct return argument.
+ ++AI;
+ ++ArgNo;
+ }
+
+ bool PrintedArg = false;
+ for (; AI != AE; ++AI, ++ArgNo) {
+ if (PrintedArg) Out << ", ";
+ if (ArgNo < NumDeclaredParams &&
+ (*AI)->getType() != FTy->getParamType(ArgNo)) {
Out << '(';
- printType(Out, FTy->getParamType(0));
+ printType(Out, FTy->getParamType(ArgNo));
Out << ')';
}
-
writeOperand(*AI);
-
- unsigned ArgNo;
- for (ArgNo = 1, ++AI; AI != AE; ++AI, ++ArgNo) {
- Out << ", ";
- if (ArgNo < NumDeclaredParams &&
- (*AI)->getType() != FTy->getParamType(ArgNo)) {
- Out << '(';
- printType(Out, FTy->getParamType(ArgNo));
- Out << ')';
- }
- writeOperand(*AI);
- }
+ PrintedArg = true;
}
Out << ')';
}
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