[PATCH] D37097: Set hasSideEffects=0 for PHI and fix passes relying isSafeToMove/hasUnmodeledSideEffects being true for PHI

[Alex Bradbury via Phabricator via llvm-commits]

asb updated this revision to Diff 112584.
asb marked an inline comment as done.
asb edited the summary of this revision.
asb added a comment.

Update to have MachineInstr::isSafeToMove return false for PHI, as requested by @qcolombet.


https://reviews.llvm.org/D37097

Files:
  include/llvm/Target/Target.td
  lib/CodeGen/MachineInstr.cpp
  lib/Target/Hexagon/HexagonBitSimplify.cpp


Index: lib/Target/Hexagon/HexagonBitSimplify.cpp
===================================================================
--- lib/Target/Hexagon/HexagonBitSimplify.cpp
+++ lib/Target/Hexagon/HexagonBitSimplify.cpp
@@ -1319,7 +1319,7 @@
 
     if (MI->getOpcode() == TargetOpcode::COPY)
       continue;
-    if (MI->hasUnmodeledSideEffects() || MI->isInlineAsm())
+    if (MI->isPHI() || MI->hasUnmodeledSideEffects() || MI->isInlineAsm())
       continue;
     unsigned NumD = MI->getDesc().getNumDefs();
     if (NumD != 1)
@@ -1329,8 +1329,7 @@
     if (!BT.has(RD.Reg))
       continue;
     const BitTracker::RegisterCell &DC = BT.lookup(RD.Reg);
-    auto At = MI->isPHI() ? B.getFirstNonPHI()
-                          : MachineBasicBlock::iterator(MI);
+    auto At = MachineBasicBlock::iterator(MI);
 
     // Find a source operand that is equal to the result.
     for (auto &Op : MI->uses()) {
Index: lib/CodeGen/MachineInstr.cpp
===================================================================
--- lib/CodeGen/MachineInstr.cpp
+++ lib/CodeGen/MachineInstr.cpp
@@ -1636,7 +1636,7 @@
   // Treat volatile loads as stores. This is not strictly necessary for
   // volatiles, but it is required for atomic loads. It is not allowed to move
   // a load across an atomic load with Ordering > Monotonic.
-  if (mayStore() || isCall() ||
+  if (mayStore() || isCall() || isPHI() ||
       (mayLoad() && hasOrderedMemoryRef())) {
     SawStore = true;
     return false;
Index: include/llvm/Target/Target.td
===================================================================
--- include/llvm/Target/Target.td
+++ include/llvm/Target/Target.td
@@ -815,7 +815,7 @@
   let OutOperandList = (outs unknown:$dst);
   let InOperandList = (ins variable_ops);
   let AsmString = "PHINODE";
-  let hasSideEffects = 1;
+  let hasSideEffects = 0;
 }
 def INLINEASM : Instruction {
   let OutOperandList = (outs);


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