Notify the linker when a TU compiled with split-stack has a function without a prologue.

More context here: https://go-review.googlesource.com/c/go/+/148819/

llvm-svn: 347614

1 files changed, 8 insertions, 2 deletions

diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index e40b0f81e33..d722c75c4f0 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -2270,9 +2270,15 @@ void X86FrameLowering::adjustForSegmentedStacks(
 
   // Do not generate a prologue for leaf functions with a stack of size zero.
   // For non-leaf functions we have to allow for the possibility that the
-  // call is to a non-split function, as in PR37807.
-  if (StackSize == 0 && !MFI.hasTailCall())
+  // callis to a non-split function, as in PR37807. This function could also
+  // take the address of a non-split function. When the linker tries to adjust
+  // its non-existent prologue, it would fail with an error. Mark the object
+  // file so that such failures are not errors. See this Go language bug-report
+  // https://go-review.googlesource.com/c/go/+/148819/
+  if (StackSize == 0 && !MFI.hasTailCall()) {
+    MF.getMMI().setHasNosplitStack(true);
     return;
+  }
 
   MachineBasicBlock *allocMBB = MF.CreateMachineBasicBlock();
   MachineBasicBlock *checkMBB = MF.CreateMachineBasicBlock();