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Fix PR850 and CodeGen/X86/2006-07-31-SingleRegClass.ll. 

The CFE refers to all single-register constraints (like "A") by their 16-bit
name, even though the 8 or 32-bit version of the register may be needed.
The X86 backend should realize what is going on and redecode the name back
to its proper form.

llvm-svn: 29420
This commit is contained in:
Chris Lattner 2006-07-31 23:26:50 +00:00
parent 9e3d4c2693
commit 524129dd64
2 changed files with 68 additions and 0 deletions
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60
llvm/lib/Target/X86/X86ISelLowering.cpp
View File

@ -4212,3 +4212,63 @@ getRegClassForInlineAsmConstraint(const std::string &Constraint,
return std::vector<unsigned>();
}
std::pair<unsigned, const TargetRegisterClass*>
X86TargetLowering::getRegForInlineAsmConstraint(const std::string &Constraint,
MVT::ValueType VT) const {
// Use the default implementation in TargetLowering to convert the register
// constraint into a member of a register class.
std::pair<unsigned, const TargetRegisterClass*> Res;
Res = TargetLowering::getRegForInlineAsmConstraint(Constraint, VT);
// Not found? Bail out.
if (Res.second == 0) return Res;
// Otherwise, check to see if this is a register class of the wrong value
// type. For example, we want to map "{ax},i32" -> {eax}, we don't want it to
// turn into {ax},{dx}.
if (Res.second->hasType(VT))
return Res; // Correct type already, nothing to do.
// All of the single-register GCC register classes map their values onto
// 16-bit register pieces "ax","dx","cx","bx","si","di","bp","sp". If we
// really want an 8-bit or 32-bit register, map to the appropriate register
// class and return the appropriate register.
if (Res.second != X86::GR16RegisterClass)
return Res;
if (VT == MVT::i8) {
unsigned DestReg = 0;
switch (Res.first) {
default: break;
case X86::AX: DestReg = X86::AL; break;
case X86::DX: DestReg = X86::DL; break;
case X86::CX: DestReg = X86::CL; break;
case X86::BX: DestReg = X86::BL; break;
}
if (DestReg) {
Res.first = DestReg;
Res.second = Res.second = X86::GR8RegisterClass;
}
} else if (VT == MVT::i32) {
unsigned DestReg = 0;
switch (Res.first) {
default: break;
case X86::AX: DestReg = X86::EAX; break;
case X86::DX: DestReg = X86::EDX; break;
case X86::CX: DestReg = X86::ECX; break;
case X86::BX: DestReg = X86::EBX; break;
case X86::SI: DestReg = X86::ESI; break;
case X86::DI: DestReg = X86::EDI; break;
case X86::BP: DestReg = X86::EBP; break;
case X86::SP: DestReg = X86::ESP; break;
}
if (DestReg) {
Res.first = DestReg;
Res.second = Res.second = X86::GR32RegisterClass;
}
}
return Res;
}

8
llvm/lib/Target/X86/X86ISelLowering.h
View File

@ -316,6 +316,14 @@ namespace llvm {
getRegClassForInlineAsmConstraint(const std::string &Constraint,
MVT::ValueType VT) const;
/// getRegForInlineAsmConstraint - Given a physical register constraint (e.g.
/// {edx}), return the register number and the register class for the
/// register. This should only be used for C_Register constraints. On error,
/// this returns a register number of 0.
std::pair<unsigned, const TargetRegisterClass*>
getRegForInlineAsmConstraint(const std::string &Constraint,
MVT::ValueType VT) const;
/// isLegalAddressImmediate - Return true if the integer value or
/// GlobalValue can be used as the offset of the target addressing mode.
virtual bool isLegalAddressImmediate(int64_t V) const;