[CodeGen] Enable tail call position check for speculatable functions
In the function "Analysis.cpp:isInTailCallPosition", it only checks whether
a call is in a tail call position if the call has side effects, access memory
or it is not safe to speculative execute. Therefore, a speculatable function
will not go through tail call position check and improperly tail called when
it is not in a tail-call position. This patch enables tail call position check
for speculatable functions.
Differential Revision: https://reviews.llvm.org/D80661
diff --git a/llvm/lib/CodeGen/Analysis.cpp b/llvm/lib/CodeGen/Analysis.cpp
index c7aafb0..7da28ff 100644
--- a/llvm/lib/CodeGen/Analysis.cpp
+++ b/llvm/lib/CodeGen/Analysis.cpp
@@ -530,24 +530,23 @@
// If I will have a chain, make sure no other instruction that will have a
// chain interposes between I and the return.
- if (Call.mayHaveSideEffects() || Call.mayReadFromMemory() ||
- !isSafeToSpeculativelyExecute(&Call))
- for (BasicBlock::const_iterator BBI = std::prev(ExitBB->end(), 2);; --BBI) {
- if (&*BBI == &Call)
- break;
- // Debug info intrinsics do not get in the way of tail call optimization.
- if (isa<DbgInfoIntrinsic>(BBI))
+ // Check for all calls including speculatable functions.
+ for (BasicBlock::const_iterator BBI = std::prev(ExitBB->end(), 2);; --BBI) {
+ if (&*BBI == &Call)
+ break;
+ // Debug info intrinsics do not get in the way of tail call optimization.
+ if (isa<DbgInfoIntrinsic>(BBI))
+ continue;
+ // A lifetime end or assume intrinsic should not stop tail call
+ // optimization.
+ if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(BBI))
+ if (II->getIntrinsicID() == Intrinsic::lifetime_end ||
+ II->getIntrinsicID() == Intrinsic::assume)
continue;
- // A lifetime end or assume intrinsic should not stop tail call
- // optimization.
- if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(BBI))
- if (II->getIntrinsicID() == Intrinsic::lifetime_end ||
- II->getIntrinsicID() == Intrinsic::assume)
- continue;
- if (BBI->mayHaveSideEffects() || BBI->mayReadFromMemory() ||
- !isSafeToSpeculativelyExecute(&*BBI))
- return false;
- }
+ if (BBI->mayHaveSideEffects() || BBI->mayReadFromMemory() ||
+ !isSafeToSpeculativelyExecute(&*BBI))
+ return false;
+ }
const Function *F = ExitBB->getParent();
return returnTypeIsEligibleForTailCall(