[X86] Do not run shrink-wrapping on function with split-stack attribute or HiPE

calling convention.
The implementation of the related callbacks in the x86 backend for such
functions are not ready to deal with a prologue block that is not the entry
block of the function.

This fixes PR26107, but the longer term solution would be to fix those callbacks.

llvm-svn: 258221

1 files changed, 17 insertions, 1 deletions

diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index 8f21fb49728..a6d395b92a0 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -2030,6 +2030,10 @@ void X86FrameLowering::adjustForSegmentedStacks(
   unsigned TlsReg, TlsOffset;
   DebugLoc DL;
 
+  // To support shrink-wrapping we would need to insert the new blocks
+  // at the right place and update the branches to PrologueMBB.
+  assert(&(*MF.begin()) == &PrologueMBB && "Shrink-wrapping not supported yet");
+
   unsigned ScratchReg = GetScratchRegister(Is64Bit, IsLP64, MF, true);
   assert(!MF.getRegInfo().isLiveIn(ScratchReg) &&
          "Scratch register is live-in");
@@ -2270,6 +2274,11 @@ void X86FrameLowering::adjustForHiPEPrologue(
     MachineFunction &MF, MachineBasicBlock &PrologueMBB) const {
   MachineFrameInfo *MFI = MF.getFrameInfo();
   DebugLoc DL;
+
+  // To support shrink-wrapping we would need to insert the new blocks
+  // at the right place and update the branches to PrologueMBB.
+  assert(&(*MF.begin()) == &PrologueMBB && "Shrink-wrapping not supported yet");
+
   // HiPE-specific values
   const unsigned HipeLeafWords = 24;
   const unsigned CCRegisteredArgs = Is64Bit ? 6 : 5;
@@ -2583,7 +2592,14 @@ bool X86FrameLowering::canUseAsEpilogue(const MachineBasicBlock &MBB) const {
 bool X86FrameLowering::enableShrinkWrapping(const MachineFunction &MF) const {
   // If we may need to emit frameless compact unwind information, give
   // up as this is currently broken: PR25614.
-  return MF.getFunction()->hasFnAttribute(Attribute::NoUnwind) || hasFP(MF);
+  return (MF.getFunction()->hasFnAttribute(Attribute::NoUnwind) || hasFP(MF)) &&
+         // The lowering of segmented stack and HiPE only support entry blocks
+         // as prologue blocks: PR26107.
+         // This limitation may be lifted if we fix:
+         // - adjustForSegmentedStacks
+         // - adjustForHiPEPrologue
+         MF.getFunction()->getCallingConv() != CallingConv::HiPE &&
+         !MF.shouldSplitStack();
 }
 
 MachineBasicBlock::iterator X86FrameLowering::restoreWin32EHStackPointers(