[llvm] [x86] Enable indirect tail calls with more arguments (PR #137643)

[Hans Wennborg via llvm-commits]

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@@ -890,27 +890,50 @@ static bool isCalleeLoad(SDValue Callee, SDValue &Chain, bool HasCallSeq) {
       LD->getExtensionType() != ISD::NON_EXTLOAD)
     return false;
 
+  // If the load's outgoing chain has more than one use, we can't (currently)
+  // move the load since we'd most likely create a loop. TODO: Maybe it could
+  // work if moveBelowOrigChain() updated *all* the chain users.
+  if (!Callee.getValue(1).hasOneUse())
+    return false;
+
   // Now let's find the callseq_start.
   while (HasCallSeq && Chain.getOpcode() != ISD::CALLSEQ_START) {
     if (!Chain.hasOneUse())
       return false;
     Chain = Chain.getOperand(0);
   }
 
-  if (!Chain.getNumOperands())
-    return false;
-  // Since we are not checking for AA here, conservatively abort if the chain
-  // writes to memory. It's not safe to move the callee (a load) across a store.
-  if (isa<MemSDNode>(Chain.getNode()) &&
-      cast<MemSDNode>(Chain.getNode())->writeMem())
+  while (true) {
+    if (!Chain.getNumOperands())
+      return false;
+    // Since we are not checking for AA here, conservatively abort if the chain
+    // writes to memory. It's not safe to move the callee (a load) across a
+    // store.
+    if (isa<MemSDNode>(Chain.getNode()) &&
+        cast<MemSDNode>(Chain.getNode())->writeMem())
+      return false;
+    // Moving across inline asm is not safe: it could do anything.
+    if (Chain.getNode()->getOpcode() == ISD::INLINEASM ||
+        Chain.getNode()->getOpcode() == ISD::INLINEASM_BR)
+      return false;
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zmodem wrote:

Done.

https://github.com/llvm/llvm-project/pull/137643