Refactor AtomicExpandPass and add a generic isAtomic() method to Instruction

Summary:
Split shouldExpandAtomicInIR() into different versions for Stores/Loads/RMWs/CmpXchgs.
Makes runOnFunction cleaner (no more redundant checking/casting), and will help moving
the X86 backend to this pass.

This requires a way of easily detecting which instructions are atomic.
I followed the pattern of mayReadFromMemory, mayWriteOrReadMemory, etc.. in making
isAtomic() a method of Instruction implemented by a switch on the opcodes.

Test Plan: make check

Reviewers: jfb

Subscribers: mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D5035

llvm-svn: 217080

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/lib/IR/Instruction.cpp b/llvm/lib/IR/Instruction.cpp
index 50b1f04d41e..3e7b0314473 100644
--- a/llvm/lib/IR/Instruction.cpp
+++ b/llvm/lib/IR/Instruction.cpp
@@ -443,6 +443,21 @@ bool Instruction::mayWriteToMemory() const {
   }
 }
 
+bool Instruction::isAtomic() const {
+  switch (getOpcode()) {
+  default:
+    return false;
+  case Instruction::AtomicCmpXchg:
+  case Instruction::AtomicRMW:
+  case Instruction::Fence:
+    return true;
+  case Instruction::Load:
+    return cast<LoadInst>(this)->getOrdering() != NotAtomic;
+  case Instruction::Store:
+    return cast<StoreInst>(this)->getOrdering() != NotAtomic;
+  }
+}
+
 bool Instruction::mayThrow() const {
   if (const CallInst *CI = dyn_cast<CallInst>(this))
     return !CI->doesNotThrow();