[PATCH] D103275: Update musttail verification to check all swiftasync->swiftasync tail calls.

[Varun Gandhi via Phabricator via llvm-commits]

varungandhi-apple created this revision.
varungandhi-apple added reviewers: aschwaighofer, davezarzycki.
Herald added subscribers: dexonsmith, hiraditya.
varungandhi-apple requested review of this revision.
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When `-enable-swifttailcc-musttail-check` is passed (off by default), we will
check that all swiftasync->swiftasync tail calls are marked `musttail`.

This can be used to catch codegen bugs with a missing `musttail`.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D103275

Files:
  llvm/lib/IR/Verifier.cpp


Index: llvm/lib/IR/Verifier.cpp
===================================================================
--- llvm/lib/IR/Verifier.cpp
+++ llvm/lib/IR/Verifier.cpp
@@ -3419,7 +3419,26 @@
   return Copy;
 }
 
+static cl::opt<bool>
+EnableSwiftTailCCMustTailCheck("enable-swifttailcc-musttail-check",
+cl::init(false), cl::desc("Check that tail calls from swifttailcc functions to"
+                          " swifttailcc functions are marked musttail."));
+
 void Verifier::verifyMustTailCall(CallInst &CI) {
+  if (!CI.isMustTailCall()) {
+#ifndef NDEBUG
+    if (EnableSwiftTailCCMustTailCheck &&
+        CI.getCallingConv() == CallingConv::SwiftTail &&
+        CI.getCaller()->getCallingConv() == CallingConv::SwiftTail &&
+        isa_and_nonnull<ReturnInst>(CI.getNextNode())) {
+      Assert(
+        false, "tail call from swifttail->swiftail should be marked musttail",
+        &CI);
+    }
+#endif
+    return;
+  }
+
   Assert(!CI.isInlineAsm(), "cannot use musttail call with inline asm", &CI);
 
   // - The caller and callee prototypes must match.  Pointer types of
@@ -3485,9 +3504,7 @@
 
 void Verifier::visitCallInst(CallInst &CI) {
   visitCallBase(CI);
-
-  if (CI.isMustTailCall())
-    verifyMustTailCall(CI);
+  verifyMustTailCall(CI);
 }
 
 void Verifier::visitInvokeInst(InvokeInst &II) {


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