[PATCH] D59981: [SelectionDAGBuilder] Flush PendingExports before creating INLINEASM_BR node for asm goto.

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added reviewers: chandlerc, efriedma.
Herald added a project: LLVM.

Since INLINEASM_BR is a terminator we need to flush the pending exports before
emitting it. If we don't do this, a TokenFactor can be inserted between it and
the BR instruction emitted to finish the callbr lowering.

It looks like nodes are glued to the INLINEASM_BR so I had to make sure we emit
the TokenFactor before that.

Not sure if we should also flush PendingLoads for asm goto as well.


Repository:
  rL LLVM

https://reviews.llvm.org/D59981

Files:
  lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp


Index: lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -7911,10 +7911,19 @@
     ExtraInfo.update(T);
   }
 
+
   // We won't need to flush pending loads if this asm doesn't touch
   // memory and is nonvolatile.
   SDValue Flag, Chain = (HasSideEffect) ? getRoot() : DAG.getRoot();
 
+  bool IsCallBr = isa<CallBrInst>(CS.getInstruction());
+  if (IsCallBr) {
+    // If this is a callbr we need to flush pending exports since inlineasm_br
+    // is a terminator. We need to do this before nodes are glued to
+    // the inlineasm_br node.
+    Chain = getControlRoot();
+  }
+
   // Second pass over the constraints: compute which constraint option to use.
   for (SDISelAsmOperandInfo &OpInfo : ConstraintOperands) {
     // If this is an output operand with a matching input operand, look up the
@@ -8171,8 +8180,7 @@
   AsmNodeOperands[InlineAsm::Op_InputChain] = Chain;
   if (Flag.getNode()) AsmNodeOperands.push_back(Flag);
 
-  unsigned ISDOpc = isa<CallBrInst>(CS.getInstruction()) ? ISD::INLINEASM_BR
-                                                         : ISD::INLINEASM;
+  unsigned ISDOpc = IsCallBr ? ISD::INLINEASM_BR : ISD::INLINEASM;
   Chain = DAG.getNode(ISDOpc, getCurSDLoc(),
                       DAG.getVTList(MVT::Other, MVT::Glue), AsmNodeOperands);
   Flag = Chain.getValue(1);
@@ -8281,7 +8289,7 @@
     Chain = DAG.getNode(ISD::TokenFactor, getCurSDLoc(), MVT::Other, OutChains);
 
   // Only Update Root if inline assembly has a memory effect.
-  if (ResultValues.empty() || HasSideEffect || !OutChains.empty())
+  if (ResultValues.empty() || HasSideEffect || !OutChains.empty() || IsCallBr)
     DAG.setRoot(Chain);
 }
 


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