[llvm] 4e0d992 - [NFC] Remove obsolete checks followed by fix of isGuaranteedToTransferExecutionToSuccessor

[Max Kazantsev via llvm-commits]

Author: Max Kazantsev
Date: 2020-03-30T12:24:41+07:00
New Revision: 4e0d9925d6a3561449bdd8def27fd3f3f1b3fb9f

URL: https://github.com/llvm/llvm-project/commit/4e0d9925d6a3561449bdd8def27fd3f3f1b3fb9f
DIFF: https://github.com/llvm/llvm-project/commit/4e0d9925d6a3561449bdd8def27fd3f3f1b3fb9f.diff

LOG: [NFC] Remove obsolete checks followed by fix of isGuaranteedToTransferExecutionToSuccessor

In past, isGuaranteedToTransferExecutionToSuccessor contained some weird logic
for volatile loads/stores that was ultimately removed by patch D65375. It's time to
remove a piece of dependent logic that used to be a workaround for the code which
is now deleted.

Reviewed By: uenoku
Differential Revision: https://reviews.llvm.org/D76918

Added: 
    

Modified: 
    llvm/lib/Analysis/InstructionPrecedenceTracking.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/InstructionPrecedenceTracking.cpp b/llvm/lib/Analysis/InstructionPrecedenceTracking.cpp
index 3f5a161c8659..a6e4455c2e6e 100644
--- a/llvm/lib/Analysis/InstructionPrecedenceTracking.cpp
+++ b/llvm/lib/Analysis/InstructionPrecedenceTracking.cpp
@@ -126,26 +126,7 @@ bool ImplicitControlFlowTracking::isSpecialInstruction(
   // to avoid wrong assumptions of sort "if A is executed and B post-dominates
   // A, then B is also executed". This is not true is there is an implicit
   // control flow instruction (e.g. a guard) between them.
-  //
-  // TODO: Currently, isGuaranteedToTransferExecutionToSuccessor returns false
-  // for volatile stores and loads because they can trap. The discussion on
-  // whether or not it is correct is still ongoing. We might want to get rid
-  // of this logic in the future. Anyways, trapping instructions shouldn't
-  // introduce implicit control flow, so we explicitly allow them here. This
-  // must be removed once isGuaranteedToTransferExecutionToSuccessor is fixed.
-  if (isGuaranteedToTransferExecutionToSuccessor(Insn))
-    return false;
-  if (isa<LoadInst>(Insn)) {
-    assert(cast<LoadInst>(Insn)->isVolatile() &&
-           "Non-volatile load should transfer execution to successor!");
-    return false;
-  }
-  if (isa<StoreInst>(Insn)) {
-    assert(cast<StoreInst>(Insn)->isVolatile() &&
-           "Non-volatile store should transfer execution to successor!");
-    return false;
-  }
-  return true;
+  return !isGuaranteedToTransferExecutionToSuccessor(Insn);
 }
 
 bool MemoryWriteTracking::isSpecialInstruction(