mirror of
https://github.com/llvm/llvm-project.git
synced 2025-05-08 14:36:07 +00:00
5ac2629823
Using OrderedInstructions::dominates as comparator for instructions in BBs without dominance relation can cause a non-deterministic order between such instructions. That in turn can cause us to materialize copies in a non-deterministic order. While this does not effect correctness, it causes some minor non-determinism in the final generated code, because values have slightly different labels. Without this patch, running -print-predicateinfo on a reasonably large module produces slightly different output on each run. This patch uses the dominator trees DFSInNum to order instruction from different BBs, which should enforce a deterministic ordering and guarantee that dominated instructions come after the instructions that dominate them. Reviewers: dberlin, efriedma, davide Reviewed By: efriedma Differential Revision: https://reviews.llvm.org/D48230 llvm-svn: 335150
52 lines
2.1 KiB
C++
52 lines
2.1 KiB
C++
//===-- OrderedInstructions.cpp - Instruction dominance function ---------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file defines utility to check dominance relation of 2 instructions.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Transforms/Utils/OrderedInstructions.h"
|
|
using namespace llvm;
|
|
|
|
bool OrderedInstructions::localDominates(const Instruction *InstA,
|
|
const Instruction *InstB) const {
|
|
assert(InstA->getParent() == InstB->getParent() &&
|
|
"Instructions must be in the same basic block");
|
|
|
|
const BasicBlock *IBB = InstA->getParent();
|
|
auto OBB = OBBMap.find(IBB);
|
|
if (OBB == OBBMap.end())
|
|
OBB = OBBMap.insert({IBB, make_unique<OrderedBasicBlock>(IBB)}).first;
|
|
return OBB->second->dominates(InstA, InstB);
|
|
}
|
|
|
|
/// Given 2 instructions, use OrderedBasicBlock to check for dominance relation
|
|
/// if the instructions are in the same basic block, Otherwise, use dominator
|
|
/// tree.
|
|
bool OrderedInstructions::dominates(const Instruction *InstA,
|
|
const Instruction *InstB) const {
|
|
// Use ordered basic block to do dominance check in case the 2 instructions
|
|
// are in the same basic block.
|
|
if (InstA->getParent() == InstB->getParent())
|
|
return localDominates(InstA, InstB);
|
|
return DT->dominates(InstA->getParent(), InstB->getParent());
|
|
}
|
|
|
|
bool OrderedInstructions::dfsBefore(const Instruction *InstA,
|
|
const Instruction *InstB) const {
|
|
// Use ordered basic block in case the 2 instructions are in the same basic
|
|
// block.
|
|
if (InstA->getParent() == InstB->getParent())
|
|
return localDominates(InstA, InstB);
|
|
|
|
DomTreeNode *DA = DT->getNode(InstA->getParent());
|
|
DomTreeNode *DB = DT->getNode(InstB->getParent());
|
|
return DA->getDFSNumIn() < DB->getDFSNumIn();
|
|
}
|