mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-11-23 19:23:23 +01:00
af0734bc33
Before this instruction supported output values, it fit fairly naturally as a terminator. However, being a terminator while also supporting outputs causes some trouble, as the physreg->vreg COPY operations cannot be in the same block. Modeling it as a non-terminator allows it to be handled the same way as invoke is handled already. Most of the changes here were created by auditing all the existing users of MachineBasicBlock::isEHPad() and MachineBasicBlock::hasEHPadSuccessor(), and adding calls to isInlineAsmBrIndirectTarget or mayHaveInlineAsmBr, as appropriate. Reviewed By: nickdesaulniers, void Differential Revision: https://reviews.llvm.org/D79794
61 lines
2.3 KiB
C++
61 lines
2.3 KiB
C++
//===-- PHIEliminationUtils.cpp - Helper functions for PHI elimination ----===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "PHIEliminationUtils.h"
|
|
#include "llvm/ADT/SmallPtrSet.h"
|
|
#include "llvm/CodeGen/MachineBasicBlock.h"
|
|
#include "llvm/CodeGen/MachineFunction.h"
|
|
#include "llvm/CodeGen/MachineRegisterInfo.h"
|
|
using namespace llvm;
|
|
|
|
// findCopyInsertPoint - Find a safe place in MBB to insert a copy from SrcReg
|
|
// when following the CFG edge to SuccMBB. This needs to be after any def of
|
|
// SrcReg, but before any subsequent point where control flow might jump out of
|
|
// the basic block.
|
|
MachineBasicBlock::iterator
|
|
llvm::findPHICopyInsertPoint(MachineBasicBlock* MBB, MachineBasicBlock* SuccMBB,
|
|
unsigned SrcReg) {
|
|
// Handle the trivial case trivially.
|
|
if (MBB->empty())
|
|
return MBB->begin();
|
|
|
|
// Usually, we just want to insert the copy before the first terminator
|
|
// instruction. However, for the edge going to a landing pad, we must insert
|
|
// the copy before the call/invoke instruction. Similarly for an INLINEASM_BR
|
|
// going to an indirect target.
|
|
if (!SuccMBB->isEHPad() && !SuccMBB->isInlineAsmBrIndirectTarget())
|
|
return MBB->getFirstTerminator();
|
|
|
|
// Discover any defs/uses in this basic block.
|
|
SmallPtrSet<MachineInstr*, 8> DefUsesInMBB;
|
|
MachineRegisterInfo& MRI = MBB->getParent()->getRegInfo();
|
|
for (MachineInstr &RI : MRI.reg_instructions(SrcReg)) {
|
|
if (RI.getParent() == MBB)
|
|
DefUsesInMBB.insert(&RI);
|
|
}
|
|
|
|
MachineBasicBlock::iterator InsertPoint;
|
|
if (DefUsesInMBB.empty()) {
|
|
// No defs. Insert the copy at the start of the basic block.
|
|
InsertPoint = MBB->begin();
|
|
} else if (DefUsesInMBB.size() == 1) {
|
|
// Insert the copy immediately after the def/use.
|
|
InsertPoint = *DefUsesInMBB.begin();
|
|
++InsertPoint;
|
|
} else {
|
|
// Insert the copy immediately after the last def/use.
|
|
InsertPoint = MBB->end();
|
|
while (!DefUsesInMBB.count(&*--InsertPoint)) {}
|
|
++InsertPoint;
|
|
}
|
|
|
|
// Make sure the copy goes after any phi nodes but before
|
|
// any debug nodes.
|
|
return MBB->SkipPHIsAndLabels(InsertPoint);
|
|
}
|