[llvm] [X86] Fix TC_RETURN selection failure for Win+Thunk combination (PR #175977)

[Nikita Popov via llvm-commits]

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@@ -0,0 +1,19 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
+; RUN: llc -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s --check-prefix=64BIT
+; RUN: llc -mtriple=i686-unknown-linux-gnu < %s | FileCheck %s --check-prefix=32BIT
+
+define void @test(ptr %g) #0 {
+; 64BIT-LABEL: test:
+; 64BIT:       # %bb.0:
+; 64BIT-NEXT:    movq %rdi, %r11
+; 64BIT-NEXT:    jmp __x86_indirect_thunk_r11 # TAILCALL
+;
+; 32BIT-LABEL: test:
+; 32BIT:       # %bb.0:
+; 32BIT-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; 32BIT-NEXT:    jmp __x86_indirect_thunk_eax # TAILCALL
+  tail call void %g()
+  ret void
+}
+
+attributes #0 = { "target-features"="+retpoline-external-thunk" }
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nikic wrote:

The original, non-reduced case had both. I found this variant made for an easier to understand test case than `+retpoline-indirect-calls`.

https://github.com/llvm/llvm-project/pull/175977