From d0446b08c42a5ee7a781c38d6b40dc1c4af48527 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Tue, 16 Jun 2009 04:06:15 +0000
Subject: [PATCH] The DWARF to compact encoding converter assumes that the
 DW_CFA_def_cfa_offset comes after the DW_CFA_def_cfa_register, because the
 CFA is really ESP from the start of the function and only gets an offset when
 the "subl $xxx,%esp" instruction happens, not the other way around.

And reapply r72898:

The DWARF unwind info was incorrect. While compiling with
`-fomit-frame-pointer', we would lack the DW_CFA_advance_loc information for a
lot of function, and then they would be `0'. The linker (at least on Darwin)
needs to encode the stack size. In some cases, the stack size is too large to
directly encode. So the linker checks to see if there is a "subl $xxx,%esp"
instruction at the point where the `DW_CFA_def_cfa_offset' says the pc was. If
so, the compact encoding records the offset in the function to where the stack
size is embedded. But because the `DW_CFA_advance_loc' instructions are missing,
it looks before the function and dies.

So, instead of emitting the EH debug label before the stack adjustment
operations, emit it afterwards, right before the frame move stuff.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73465 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/X86RegisterInfo.cpp | 38 ++++++++++++++----------------
 1 file changed, 18 insertions(+), 20 deletions(-)

diff --git a/lib/Target/X86/X86RegisterInfo.cpp b/lib/Target/X86/X86RegisterInfo.cpp
index 6c0074e62f2..a9bbf3d1a6e 100644
--- a/lib/Target/X86/X86RegisterInfo.cpp
+++ b/lib/Target/X86/X86RegisterInfo.cpp
@@ -662,6 +662,17 @@ void X86RegisterInfo::emitFrameMoves(MachineFunction &MF,
      TargetFrameInfo::StackGrowsUp ?
      TD->getPointerSize() : -TD->getPointerSize());
 
+  if (hasFP(MF)) {
+    // Save FP
+    MachineLocation FPDst(MachineLocation::VirtualFP, 2*stackGrowth);
+    MachineLocation FPSrc(FramePtr);
+    Moves.push_back(MachineMove(ReadyLabelId, FPDst, FPSrc));
+  }
+
+  MachineLocation FPDst(hasFP(MF) ? FramePtr : StackPtr);
+  MachineLocation FPSrc(MachineLocation::VirtualFP);
+  Moves.push_back(MachineMove(ReadyLabelId, FPDst, FPSrc));
+
   if (StackSize) {
     // Show update of SP.
     if (hasFP(MF)) {
@@ -676,7 +687,7 @@ void X86RegisterInfo::emitFrameMoves(MachineFunction &MF,
       Moves.push_back(MachineMove(FrameLabelId, SPDst, SPSrc));
     }
   } else {
-    //FIXME: Verify & implement for FP
+    // FIXME: Verify & implement for FP
     MachineLocation SPDst(StackPtr);
     MachineLocation SPSrc(StackPtr, stackGrowth);
     Moves.push_back(MachineMove(FrameLabelId, SPDst, SPSrc));
@@ -704,17 +715,6 @@ void X86RegisterInfo::emitFrameMoves(MachineFunction &MF,
     MachineLocation CSSrc(Reg);
     Moves.push_back(MachineMove(FrameLabelId, CSDst, CSSrc));
   }
-
-  if (hasFP(MF)) {
-    // Save FP
-    MachineLocation FPDst(MachineLocation::VirtualFP, 2*stackGrowth);
-    MachineLocation FPSrc(FramePtr);
-    Moves.push_back(MachineMove(ReadyLabelId, FPDst, FPSrc));
-  }
-
-  MachineLocation FPDst(hasFP(MF) ? FramePtr : StackPtr);
-  MachineLocation FPSrc(MachineLocation::VirtualFP);
-  Moves.push_back(MachineMove(ReadyLabelId, FPDst, FPSrc));
 }
 
 
@@ -822,13 +822,6 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
     NumBytes = StackSize - X86FI->getCalleeSavedFrameSize();
   }
 
-  unsigned ReadyLabelId = 0;
-  if (needsFrameMoves) {
-    // Mark effective beginning of when frame pointer is ready.
-    ReadyLabelId = MMI->NextLabelID();
-    BuildMI(MBB, MBBI, DL, TII.get(X86::DBG_LABEL)).addImm(ReadyLabelId);
-  }
-
   // Skip the callee-saved push instructions.
   while (MBBI != MBB.end() &&
          (MBBI->getOpcode() == X86::PUSH32r ||
@@ -891,8 +884,13 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
       emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, TII);
   }
 
-  if (needsFrameMoves)
+  if (needsFrameMoves) {
+    unsigned ReadyLabelId = 0;
+    // Mark effective beginning of when frame pointer is ready.
+    ReadyLabelId = MMI->NextLabelID();
+    BuildMI(MBB, MBBI, DL, TII.get(X86::DBG_LABEL)).addImm(ReadyLabelId);
     emitFrameMoves(MF, FrameLabelId, ReadyLabelId);
+  }
 }
 
 void X86RegisterInfo::emitEpilogue(MachineFunction &MF,