Imported Upstream version 6.0.0.172

Former-commit-id: f3cc9b82f3e5bd8f0fd3ebc098f789556b44e9cd

external/llvm/test/CodeGen/X86/tail-call-mutable-memarg.ll

@@ -0,0 +1,42 @@
+; RUN: llc < %s | FileCheck %s
+
+; Make sure we check that forwarded memory arguments are not modified when tail
+; calling. inalloca and copy arg elimination make argument slots mutable.
+
+target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
+target triple = "i386-pc-windows-msvc19.0.24215"
+
+declare x86_stdcallcc void @tail_std(i32)
+declare void @capture(i32*)
+
+define x86_thiscallcc void @inalloca(i32* %this, i32* inalloca %args) {
+entry:
+  %val = load i32, i32* %args
+  store i32 0, i32* %args
+  tail call x86_stdcallcc void @tail_std(i32 %val)
+  ret void
+}
+
+; CHECK-LABEL: _inalloca:                              # @inalloca
+; CHECK:         movl    4(%esp), %[[reg:[^ ]*]]
+; CHECK:         movl    $0, 4(%esp)
+; CHECK:         pushl   %[[reg]]
+; CHECK:         calll   _tail_std@4
+; CHECK:         retl    $4
+
+define x86_stdcallcc void @copy_elide(i32 %arg) {
+entry:
+  %arg.ptr = alloca i32
+  store i32 %arg, i32* %arg.ptr
+  call void @capture(i32* %arg.ptr)
+  tail call x86_stdcallcc void @tail_std(i32 %arg)
+  ret void
+}
+
+; CHECK-LABEL: _copy_elide@4:                          # @copy_elide
+; CHECK:         leal    {{[0-9]+}}(%esp), %[[reg:[^ ]*]]
+; CHECK:         pushl   %[[reg]]
+; CHECK:         calll   _capture
+; ...
+; CHECK:         calll   _tail_std@4
+; CHECK:         retl    $4