[llvm] [CodeGen][X86] Fix lowering of tailcalls when `-ms-hotpatch` is used (PR #77245)

[Shengchen Kan via llvm-commits]

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@@ -0,0 +1,55 @@
+; RUN: llc -verify-machineinstrs < %s | FileCheck %s --check-prefix=CHECK
+
+; CHECK: "?mi_new_test@@YAPEAX_K at Z":
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: jmp     mi_new                          # TAILCALL
+
+; CHECK: "?builtin_malloc_test@@YAPEAX_K at Z":
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: jmp     malloc                          # TAILCALL
+
+; // Built with: clang-cl.exe /c patchable-prologue-tailcall.cpp /O2 /hotpatch -Xclang -emit-llvm
+;
+; typedef unsigned long long size_t;
+; 
+; extern "C" {
+;     void* mi_new(size_t size);
+;  }
+;
+; void *mi_new_test(size_t count)
+; {
+;     return mi_new(count);
+; }
+; 
+; void *builtin_malloc_test(size_t count)
+; {
+;     return __builtin_malloc(count);
+; }
+
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KanRobert wrote:

Drop this comment, it is just saying how to write a tailcall, which should be straightforward for developers.

https://github.com/llvm/llvm-project/pull/77245