Peephole opt needs optimizeSelect() to keep track of newly created MIs

Peephole optimizer is scanning a basic block forward. At some point it 
needs to answer the question "given a pointer to an MI in the current 
BB, is it located before or after the current instruction".
To perform this, it keeps a set of the MIs already seen during the scan, 
if a MI is not in the set, it is assumed to be after.
It means that newly created MIs have to be inserted in the set as well.

This commit passes the set as an argument to the target-dependent 
optimizeSelect() so that it can properly update the set with the 
(potentially) newly created MIs.

llvm-svn: 225772

1 files changed, 13 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/PeepholeOptimizer.cpp b/llvm/lib/CodeGen/PeepholeOptimizer.cpp
index a296aea58b7..283d1f26198 100644
--- a/llvm/lib/CodeGen/PeepholeOptimizer.cpp
+++ b/llvm/lib/CodeGen/PeepholeOptimizer.cpp
@@ -133,7 +133,8 @@ namespace {
     bool optimizeCmpInstr(MachineInstr *MI, MachineBasicBlock *MBB);
     bool optimizeExtInstr(MachineInstr *MI, MachineBasicBlock *MBB,
                           SmallPtrSetImpl<MachineInstr*> &LocalMIs);
-    bool optimizeSelect(MachineInstr *MI);
+    bool optimizeSelect(MachineInstr *MI,
+                        SmallPtrSetImpl<MachineInstr *> &LocalMIs);
     bool optimizeCondBranch(MachineInstr *MI);
     bool optimizeCopyOrBitcast(MachineInstr *MI);
     bool optimizeCoalescableCopy(MachineInstr *MI);
@@ -482,7 +483,8 @@ bool PeepholeOptimizer::optimizeCmpInstr(MachineInstr *MI,
 }
 
 /// Optimize a select instruction.
-bool PeepholeOptimizer::optimizeSelect(MachineInstr *MI) {
+bool PeepholeOptimizer::optimizeSelect(MachineInstr *MI,
+                            SmallPtrSetImpl<MachineInstr *> &LocalMIs) {
   unsigned TrueOp = 0;
   unsigned FalseOp = 0;
   bool Optimizable = false;
@@ -491,7 +493,7 @@ bool PeepholeOptimizer::optimizeSelect(MachineInstr *MI) {
     return false;
   if (!Optimizable)
     return false;
-  if (!TII->optimizeSelect(MI))
+  if (!TII->optimizeSelect(MI, LocalMIs))
     return false;
   MI->eraseFromParent();
   ++NumSelects;
@@ -1072,6 +1074,13 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
     MachineBasicBlock *MBB = &*I;
 
     bool SeenMoveImm = false;
+
+    // During this forward scan, at some point it needs to answer the question
+    // "given a pointer to an MI in the current BB, is it located before or
+    // after the current instruction".
+    // To perform this, the following set keeps track of the MIs already seen
+    // during the scan, if a MI is not in the set, it is assumed to be located
+    // after. Newly created MIs have to be inserted in the set as well.
     SmallPtrSet<MachineInstr*, 16> LocalMIs;
     SmallSet<unsigned, 4> ImmDefRegs;
     DenseMap<unsigned, MachineInstr*> ImmDefMIs;
@@ -1102,7 +1111,7 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
       if ((isUncoalescableCopy(*MI) &&
            optimizeUncoalescableCopy(MI, LocalMIs)) ||
           (MI->isCompare() && optimizeCmpInstr(MI, MBB)) ||
-          (MI->isSelect() && optimizeSelect(MI))) {
+          (MI->isSelect() && optimizeSelect(MI, LocalMIs))) {
         // MI is deleted.
         LocalMIs.erase(MI);
         Changed = true;