From 9f4692d2953b47e9037ccfe5709a6e75de3911d4 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Mon, 17 Dec 2012 23:55:38 +0000
Subject: Tighten up the erase/remove API for bundled instructions.

Most code is oblivious to bundles and uses the MBB::iterator which only
visits whole bundles. MBB::erase() operates on whole bundles at a time
as before.

MBB::remove() now refuses to remove bundled instructions. It is not safe
to remove all instructions in a bundle without deleting them since there
is no way of returning pointers to all the removed instructions.

MBB::remove_instr() and MBB::erase_instr() will now update bundle flags
correctly, lifting individual instructions out of bundles while leaving
the remaining bundle intact.

The MachineInstr convenience functions are updated so

  eraseFromParent() erases a whole bundle as before
  eraseFromBundle() erases a single instruction, leaving the rest of its bundle.
  removeFromParent() refuses to operate on bundled instructions, and
  removeFromBundle() lifts a single instruction out of its bundle.

These functions will no longer accidentally split or coalesce bundles -
bundle flags are updated to preserve the existing bundling, and explicit
bundleWith* / unbundleFrom* functions should be used to change the
instruction bundling.

This API update is still a work in progress. I am going to update APIs
first so they maintain bundle flags automatically when possible. Then
I'll add stricter verification of the bundle flags.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170384 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/MachineInstr.cpp | 41 ++++++++++-------------------------------
 1 file changed, 10 insertions(+), 31 deletions(-)

(limited to 'lib/CodeGen/MachineInstr.cpp')

diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index 3aebdcdabb..f545a9ce56 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -838,46 +838,25 @@ bool MachineInstr::isIdenticalTo(const MachineInstr *Other,
   return true;
 }
 
-/// removeFromParent - This method unlinks 'this' from the containing basic
-/// block, and returns it, but does not delete it.
 MachineInstr *MachineInstr::removeFromParent() {
   assert(getParent() && "Not embedded in a basic block!");
-
-  // If it's a bundle then remove the MIs inside the bundle as well.
-  if (isBundle()) {
-    MachineBasicBlock *MBB = getParent();
-    MachineBasicBlock::instr_iterator MII = *this; ++MII;
-    MachineBasicBlock::instr_iterator E = MBB->instr_end();
-    while (MII != E && MII->isInsideBundle()) {
-      MachineInstr *MI = &*MII;
-      ++MII;
-      MBB->remove(MI);
-    }
-  }
-  getParent()->remove(this);
-  return this;
+  return getParent()->remove(this);
 }
 
+MachineInstr *MachineInstr::removeFromBundle() {
+  assert(getParent() && "Not embedded in a basic block!");
+  return getParent()->remove_instr(this);
+}
 
-/// eraseFromParent - This method unlinks 'this' from the containing basic
-/// block, and deletes it.
 void MachineInstr::eraseFromParent() {
   assert(getParent() && "Not embedded in a basic block!");
-  // If it's a bundle then remove the MIs inside the bundle as well.
-  if (isBundle()) {
-    MachineBasicBlock *MBB = getParent();
-    MachineBasicBlock::instr_iterator MII = *this; ++MII;
-    MachineBasicBlock::instr_iterator E = MBB->instr_end();
-    while (MII != E && MII->isInsideBundle()) {
-      MachineInstr *MI = &*MII;
-      ++MII;
-      MBB->erase(MI);
-    }
-  }
-  // Erase the individual instruction, which may itself be inside a bundle.
-  getParent()->erase_instr(this);
+  getParent()->erase(this);
 }
 
+void MachineInstr::eraseFromBundle() {
+  assert(getParent() && "Not embedded in a basic block!");
+  getParent()->erase_instr(this);
+}
 
 /// getNumExplicitOperands - Returns the number of non-implicit operands.
 ///
-- 
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