[PATCH] D54492: Notify the linker when a TU compiled with split-stack has a functionwithout a prologue.There is more context here:https://go-review.googlesource.com/c/go/+/148819/

[Sterling Augustine via Phabricator via llvm-commits]

saugustine updated this revision to Diff 175354.
saugustine added a comment.

Add a test case.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D54492/new/

https://reviews.llvm.org/D54492

Files:
  lib/Target/ARM/ARMFrameLowering.cpp
  lib/Target/X86/X86FrameLowering.cpp
  test/CodeGen/X86/segmented-stacks-standalone.ll


Index: test/CodeGen/X86/segmented-stacks-standalone.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/segmented-stacks-standalone.ll
@@ -0,0 +1,30 @@
+; RUN: llc < %s -mcpu=generic -mtriple=i686-linux -verify-machineinstrs | FileCheck %s -check-prefix=X32-Linux
+; RUN: llc < %s -mcpu=generic -mtriple=x86_64-linux  -verify-machineinstrs | FileCheck %s -check-prefix=X64-Linux
+
+; This test is standalone because segmented-stacks.ll generates
+; object-files with both .note.GNU-split-stack (for the split-stack
+; functions) and .note.GNU-no-split-stack sections (for the
+; non-split-stack functions). But a split-stack function without a
+; stack frame should have a .note.GNU-split-stack section regardless
+; of any other contents of the compilation unit.
+
+define void @test_nostack() #0 {
+	ret void
+}
+
+attributes #0 = { "split-stack" }
+
+; X32-Linux: .section ".note.GNU-split-stack","", at progbits
+; X32-Linux: .section ".note.GNU-no-split-stack","", at progbits
+
+; X64-Linux: .section ".note.GNU-split-stack","", at progbits
+; X64-Linux: .section ".note.GNU-no-split-stack","", at progbits
+
+; X64-FreeBSD: .section ".note.GNU-split-stack","", at progbits
+; X64-FreeBSD: .section ".note.GNU-no-split-stack","", at progbits
+
+; X32-DFlyBSD: .section ".note.GNU-split-stack","", at progbits
+; X32-DFlyBSD: .section ".note.GNU-no-split-stack","", at progbits
+
+; X64-DFlyBSD: .section ".note.GNU-split-stack","", at progbits
+; X64-DFlyBSD: .section ".note.GNU-no-split-stack","", at progbits
Index: lib/Target/X86/X86FrameLowering.cpp
===================================================================
--- lib/Target/X86/X86FrameLowering.cpp
+++ lib/Target/X86/X86FrameLowering.cpp
@@ -2270,9 +2270,15 @@
 
   // 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();
Index: lib/Target/ARM/ARMFrameLowering.cpp
===================================================================
--- lib/Target/ARM/ARMFrameLowering.cpp
+++ lib/Target/ARM/ARMFrameLowering.cpp
@@ -2157,9 +2157,15 @@
 
   // 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;
+  }
 
   // Use R4 and R5 as scratch registers.
   // We save R4 and R5 before use and restore them before leaving the function.


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