[CodeGen] Mark setjmp/catchret MBBs address-taken

Summary:
This ensures that BranchFolding (and similar) won't remove these blocks.

Also allow AsmPrinter::EmitBasicBlockStart to process MBBs which are
address-taken but do not have BBs that are address-taken, since otherwise
its call to getAddrLabelSymbolTableToEmit would fail an assertion on such
blocks.  I audited the other callers of getAddrLabelSymbolTableToEmit
(and getAddrLabelSymbol); they all have BBs known to be address-taken
except for the call through getAddrLabelSymbol from
WinException::create32bitRef; that call is actually now unreachable, so
I've removed it and updated the signature of create32bitRef.

This fixes PR25168.

Reviewers: majnemer, andrew.w.kaylor, rnk

Subscribers: pgavlin, llvm-commits

Differential Revision: http://reviews.llvm.org/D13774

llvm-svn: 251113

5 files changed, 15 insertions, 9 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 52dbd5a9df4..f073118fd00 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -2480,8 +2480,11 @@ void AsmPrinter::EmitBasicBlockStart(const MachineBasicBlock &MBB) const {
     if (isVerbose())
       OutStreamer->AddComment("Block address taken");
 
-    for (MCSymbol *Sym : MMI->getAddrLabelSymbolToEmit(BB))
-      OutStreamer->EmitLabel(Sym);
+    // MBBs can have their address taken as part of CodeGen without having
+    // their corresponding BB's address taken in IR
+    if (BB->hasAddressTaken())
+      for (MCSymbol *Sym : MMI->getAddrLabelSymbolToEmit(BB))
+        OutStreamer->EmitLabel(Sym);
   }
 
   // Print some verbose block comments.
diff --git a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
index 58103836a09..3999268b407 100644
--- a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
@@ -273,12 +273,10 @@ const MCExpr *WinException::create32bitRef(const MCSymbol *Value) {
                                  Asm->OutContext);
 }
 
-const MCExpr *WinException::create32bitRef(const Value *V) {
-  if (!V)
+const MCExpr *WinException::create32bitRef(const GlobalValue *GV) {
+  if (!GV)
     return MCConstantExpr::create(0, Asm->OutContext);
-  if (const auto *GV = dyn_cast<GlobalValue>(V))
-    return create32bitRef(Asm->getSymbol(GV));
-  return create32bitRef(MMI->getAddrLabelSymbol(cast<BasicBlock>(V)));
+  return create32bitRef(Asm->getSymbol(GV));
 }
 
 const MCExpr *WinException::getLabelPlusOne(const MCSymbol *Label) {
diff --git a/llvm/lib/CodeGen/AsmPrinter/WinException.h b/llvm/lib/CodeGen/AsmPrinter/WinException.h
index e553c3ff736..02134d6aa98 100644
--- a/llvm/lib/CodeGen/AsmPrinter/WinException.h
+++ b/llvm/lib/CodeGen/AsmPrinter/WinException.h
@@ -18,6 +18,7 @@
 
 namespace llvm {
 class Function;
+class GlobalValue;
 class MachineFunction;
 class MCExpr;
 class Value;
@@ -66,7 +67,7 @@ class LLVM_LIBRARY_VISIBILITY WinException : public EHStreamer {
                                      StringRef FLinkageName);
 
   const MCExpr *create32bitRef(const MCSymbol *Value);
-  const MCExpr *create32bitRef(const Value *V);
+  const MCExpr *create32bitRef(const GlobalValue *GV);
   const MCExpr *getLabelPlusOne(const MCSymbol *Label);
   const MCExpr *getOffset(const MCSymbol *OffsetOf, const MCSymbol *OffsetFrom);
   const MCExpr *getOffsetPlusOne(const MCSymbol *OffsetOf,
diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index a1a18fe6bd2..95cb76094ec 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -1178,6 +1178,9 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF,
           .addReg(ReturnReg)
           .addMBB(RestoreMBB);
     }
+    // Record that we've taken the address of RestoreMBB and no longer just
+    // reference it in a terminator.
+    RestoreMBB->setHasAddressTaken();
   }
 
   if (MBBI != MBB.end())
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 0de6acd5879..0d0e4823c38 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -21471,7 +21471,7 @@ X86TargetLowering::emitEHSjLjSetJmp(MachineInstr *MI,
   // For v = setjmp(buf), we generate
   //
   // thisMBB:
-  //  buf[LabelOffset] = restoreMBB
+  //  buf[LabelOffset] = restoreMBB <-- takes address of restoreMBB
   //  SjLjSetup restoreMBB
   //
   // mainMBB:
@@ -21491,6 +21491,7 @@ X86TargetLowering::emitEHSjLjSetJmp(MachineInstr *MI,
   MF->insert(I, mainMBB);
   MF->insert(I, sinkMBB);
   MF->push_back(restoreMBB);
+  restoreMBB->setHasAddressTaken();
 
   MachineInstrBuilder MIB;