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[mips] Fix expansion of memory operation if destination register is not a GPR.

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Summary:
The assembler tries to reuse the destination register for memory operations whenever
it can but it's not possible to do so if the destination register is not a GPR.

Example:
  ldc1 $f0, sym
should expand to:
  lui $at, %hi(sym)
  ldc1 $f0, %lo(sym)($at)

It's entirely wrong to expand to:
  lui $f0, %hi(sym)
  ldc1 $f0, %lo(sym)($f0)

Reviewers: dsanders

Reviewed By: dsanders

Differential Revision: http://reviews.llvm.org/D4173

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211169 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Matheus Almeida
2014-06-18 14:49:56 +00:00
parent cacc062572
commit c39b18b306
2 changed files with 37 additions and 4 deletions
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33
lib/Target/Mips/AsmParser/MipsAsmParser.cpp
View File

@@ -1144,10 +1144,35 @@ void MipsAsmParser::expandMemInst(MCInst &Inst, SMLoc IDLoc,
ExprOffset = Inst.getOperand(2).getExpr();
// All instructions will have the same location.
TempInst.setLoc(IDLoc);
// 1st instruction in expansion is LUi. For load instruction we can use
// the dst register as a temporary if base and dst are different,
// but for stores we must use $at.
if (isLoad && (BaseRegNum != RegOpNum))
// These are some of the types of expansions we perform here:
// 1) lw $8, sym => lui $8, %hi(sym)
// lw $8, %lo(sym)($8)
// 2) lw $8, offset($9) => lui $8, %hi(offset)
// add $8, $8, $9
// lw $8, %lo(offset)($9)
// 3) lw $8, offset($8) => lui $at, %hi(offset)
// add $at, $at, $8
// lw $8, %lo(offset)($at)
// 4) sw $8, sym => lui $at, %hi(sym)
// sw $8, %lo(sym)($at)
// 5) sw $8, offset($8) => lui $at, %hi(offset)
// add $at, $at, $8
// sw $8, %lo(offset)($at)
// 6) ldc1 $f0, sym => lui $at, %hi(sym)
// ldc1 $f0, %lo(sym)($at)
//
// For load instructions we can use the destination register as a temporary
// if base and dst are different (examples 1 and 2) and if the base register
// is general purpose otherwise we must use $at (example 6) and error if it's
// not available. For stores we must use $at (examples 4 and 5) because we
// must not clobber the source register setting up the offset.
const MCInstrDesc &Desc = getInstDesc(Inst.getOpcode());
int16_t RegClassOp0 = Desc.OpInfo[0].RegClass;
unsigned RegClassIDOp0 =
getContext().getRegisterInfo()->getRegClass(RegClassOp0).getID();
bool IsGPR = (RegClassIDOp0 == Mips::GPR32RegClassID) ||
(RegClassIDOp0 == Mips::GPR64RegClassID);
if (isLoad && IsGPR && (BaseRegNum != RegOpNum))
TmpRegNum = RegOpNum;
else {
int AT = getATReg(IDLoc);