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[x86] Hoist the logic for extracting the relevant bits of information 

from the MachineInstr into the caller which is already doing a switch
over the instruction.

This will make it more clear how to compute different operands to feed
the comment selection for example.

Also, in a drive-by-fix, don't append an empty comment string (which is
a no-op ultimately).

No functionality changed.

llvm-svn: 218361
This commit is contained in:
Chandler Carruth 2014-09-24 02:24:41 +00:00
parent 2c41987490
commit ab8b37a9d2
1 changed files with 20 additions and 16 deletions
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36
llvm/lib/Target/X86/X86MCInstLower.cpp
View File

@ -864,22 +864,16 @@ PrevCrossBBInst(MachineBasicBlock::const_iterator MBBI) {
return --MBBI;
}
static std::string getShuffleComment(const MachineInstr &MI) {
static std::string getShuffleComment(int Opcode, const MachineOperand &DstOp,
const MachineOperand &SrcOp,
const MachineOperand &MaskOp,
ArrayRef<MachineConstantPoolEntry> Constants) {
std::string Comment;
SmallVector<int, 16> Mask;
// All of these instructions accept a constant pool operand as their fifth.
assert(MI.getNumOperands() > 5 &&
"We should always have at least 5 operands!");
const MachineOperand &DstOp = MI.getOperand(0);
const MachineOperand &SrcOp = MI.getOperand(1);
const MachineOperand &MaskOp = MI.getOperand(5);
if (!MaskOp.isCPI())
return Comment;
ArrayRef<MachineConstantPoolEntry> Constants =
MI.getParent()->getParent()->getConstantPool()->getConstants();
const MachineConstantPoolEntry &MaskConstantEntry =
Constants[MaskOp.getIndex()];
@ -895,7 +889,7 @@ static std::string getShuffleComment(const MachineInstr &MI) {
assert(MaskConstantEntry.getType() == C->getType() &&
"Expected a constant of the same type!");
switch (MI.getOpcode()) {
switch (Opcode) {
case X86::PSHUFBrm:
case X86::VPSHUFBrm:
DecodePSHUFBMask(C, Mask);
@ -1118,17 +1112,27 @@ void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) {
return;
}
// Lower PSHUFB and VPERMILP normally but add a comment if we can find
// a constant shuffle mask. We won't be able to do this at the MC layer
// because the mask isn't an immediate.
case X86::PSHUFBrm:
case X86::VPSHUFBrm:
case X86::VPERMILPSrm:
case X86::VPERMILPDrm:
case X86::VPERMILPSYrm:
case X86::VPERMILPDYrm: {
// Lower PSHUFB and VPERMILP normally but add a comment if we can find
// a constant shuffle mask. We won't be able to do this at the MC layer
// because the mask isn't an immediate.
std::string Comment = getShuffleComment(*MI);
OutStreamer.AddComment(Comment);
// All of these instructions accept a constant pool operand as their fifth.
assert(MI->getNumOperands() > 5 &&
"We should always have at least 5 operands!");
const MachineOperand &DstOp = MI->getOperand(0);
const MachineOperand &SrcOp = MI->getOperand(1);
const MachineOperand &MaskOp = MI->getOperand(5);
std::string Comment = getShuffleComment(
MI->getOpcode(), DstOp, SrcOp, MaskOp,
MI->getParent()->getParent()->getConstantPool()->getConstants());
if (!Comment.empty())
OutStreamer.AddComment(Comment);
break;
}
}