This patch is needed to make c++ exceptions work for mips16.

Mips16 is really a processor decoding mode (ala thumb 1) and in the same
program, mips16 and mips32 functions can exist and can call each other.

If a jal type instruction encounters an address with the lower bit set, then
the processor switches to mips16 mode (if it is not already in it). If the
lower bit is not set, then it switches to mips32 mode.

The linker knows which functions are mips16 and which are mips32.
When relocation is performed on code labels, this lower order bit is
set if the code label is a mips16 code label.

In general this works just fine, however when creating exception handling
tables and dwarf, there are cases where you don't want this lower order
bit added in.

This has been traditionally distinguished in gas assembly source by using a
different syntax for the label.

lab1:      ; this will cause the lower order bit to be added
lab2=.     ; this will not cause the lower order bit to be added

In some cases, it does not matter because in dwarf and debug tables
the difference of two labels is used and in that case the lower order
bits subtract each other out.

To fix this, I have added to mcstreamer the notion of a debuglabel.
The default is for label and debug label to be the same. So calling
EmitLabel and EmitDebugLabel produce the same result.

For various reasons, there is only one set of labels that needs to be
modified for the mips exceptions to work. These are the "$eh_func_beginXXX"
labels.

Mips overrides the debug label suffix from ":" to "=." .

This initial patch fixes exceptions. More changes most likely
will be needed to DwarfCFException to make all of this work
for actual debugging. These changes will be to emit debug labels in some
places where a simple label is emitted now.

Some historical discussion on this from gcc can be found at:
http://gcc.gnu.org/ml/gcc-patches/2008-08/msg00623.html
http://gcc.gnu.org/ml/gcc-patches/2008-11/msg01273.html

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170279 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/MC/MCAsmInfo.h b/include/llvm/MC/MCAsmInfo.h
index 45f03300aec03084cebd3daaaa52d195819f04bb..38cf060636a91a837e7f6435a82add1cd19aa15b 100644 (file)
--- a/include/llvm/MC/MCAsmInfo.h
+++ b/include/llvm/MC/MCAsmInfo.h
@@ -102,6 +102,9 @@ namespace llvm {
     /// LabelSuffix - This is appended to emitted labels.
     const char *LabelSuffix;                 // Defaults to ":"
 
+    /// LabelSuffix - This is appended to emitted labels.
+    const char *DebugLabelSuffix;                 // Defaults to ":"
+
     /// GlobalPrefix - If this is set to a non-empty string, it is prepended
     /// onto all global symbols.  This is often used for "_" or ".".
     const char *GlobalPrefix;                // Defaults to ""
@@ -426,6 +429,11 @@ namespace llvm {
     const char *getLabelSuffix() const {
       return LabelSuffix;
     }
+
+    const char *getDebugLabelSuffix() const {
+      return DebugLabelSuffix;
+    }
+
     const char *getGlobalPrefix() const {
       return GlobalPrefix;
     }

diff --git a/include/llvm/MC/MCELFStreamer.h b/include/llvm/MC/MCELFStreamer.h
index 3b0152bba41da8ec540ee6dbcbe7568884703c59..03a57c7ee31e5ccbf7d9cdcd9276bf93016cda5f 100644 (file)
--- a/include/llvm/MC/MCELFStreamer.h
+++ b/include/llvm/MC/MCELFStreamer.h
@@ -47,6 +47,7 @@ public:
   virtual void InitSections();
   virtual void ChangeSection(const MCSection *Section);
   virtual void EmitLabel(MCSymbol *Symbol);
+  virtual void EmitDebugLabel(MCSymbol *Symbol);
   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
   virtual void EmitThumbFunc(MCSymbol *Func);
   virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol);

diff --git a/include/llvm/MC/MCObjectStreamer.h b/include/llvm/MC/MCObjectStreamer.h
index 843304b07fde28a7b4feb7d755b48b51484cea3c..df98fea41c6a993d12365990ecbe8ca90a2d1277 100644 (file)
--- a/include/llvm/MC/MCObjectStreamer.h
+++ b/include/llvm/MC/MCObjectStreamer.h
@@ -69,6 +69,7 @@ public:
   /// @{
 
   virtual void EmitLabel(MCSymbol *Symbol);
+  virtual void EmitDebugLabel(MCSymbol *Symbol);
   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
   virtual void EmitValueImpl(const MCExpr *Value, unsigned Size,
                              unsigned AddrSpace);

diff --git a/include/llvm/MC/MCStreamer.h b/include/llvm/MC/MCStreamer.h
index 555bf1f285e08d7de3a946512cc32f2130f1537c..ecf5e78b5e60dcffd69bedf11419d3018c0b8391 100644 (file)
--- a/include/llvm/MC/MCStreamer.h
+++ b/include/llvm/MC/MCStreamer.h
@@ -244,6 +244,8 @@ namespace llvm {
     /// used in an assignment.
     virtual void EmitLabel(MCSymbol *Symbol);
 
+    virtual void EmitDebugLabel(MCSymbol *Symbol);
+
     virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
                                      MCSymbol *EHSymbol);
 

diff --git a/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp b/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
index 2d7a5f32ae537cf0ea024c32f55186de710a60ed..aec21f1c2fa7cd508ff87fa64e1d674074e1750e 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
@@ -122,8 +122,9 @@ void DwarfCFIException::BeginFunction(const MachineFunction *MF) {
   const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(Per, Asm->Mang, MMI);
   Asm->OutStreamer.EmitCFIPersonality(Sym, PerEncoding);
 
-  Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
-                                                Asm->getFunctionNumber()));
+  Asm->OutStreamer.EmitDebugLabel
+    (Asm->GetTempSymbol("eh_func_begin",
+                        Asm->getFunctionNumber()));
 
   // Provide LSDA information.
   if (!shouldEmitLSDA)

diff --git a/lib/MC/MCAsmInfo.cpp b/lib/MC/MCAsmInfo.cpp
index 7ea0f3b85a53b15dd7a79dce862ef24334dea6f0..a6fa6582abe829043631e12279fd8f7916418c32 100644 (file)
--- a/lib/MC/MCAsmInfo.cpp
+++ b/lib/MC/MCAsmInfo.cpp
@@ -37,6 +37,7 @@ MCAsmInfo::MCAsmInfo() {
   CommentColumn = 40;
   CommentString = "#";
   LabelSuffix = ":";
+  DebugLabelSuffix = ":";
   GlobalPrefix = "";
   PrivateGlobalPrefix = ".";
   LinkerPrivateGlobalPrefix = "";

diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 6537e4e685b41e575690ab59a2648e1816e0fec5..6302f970d8e9e45a98b54c2ac2c32d37a12ab7b6 100644 (file)
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -135,6 +135,8 @@ public:
   }
 
   virtual void EmitLabel(MCSymbol *Symbol);
+  virtual void EmitDebugLabel(MCSymbol *Symbol);
+
   virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
                                    MCSymbol *EHSymbol);
   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
@@ -345,6 +347,14 @@ void MCAsmStreamer::EmitLabel(MCSymbol *Symbol) {
   EmitEOL();
 }
 
+void MCAsmStreamer::EmitDebugLabel(MCSymbol *Symbol) {
+  assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
+  MCStreamer::EmitDebugLabel(Symbol);
+
+  OS << *Symbol << MAI.getDebugLabelSuffix();
+  EmitEOL();
+}
+
 void MCAsmStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
   switch (Flag) {
   case MCAF_SyntaxUnified:         OS << "\t.syntax unified"; break;

diff --git a/lib/MC/MCELFStreamer.cpp b/lib/MC/MCELFStreamer.cpp
index 8b9bdb14a073b2d332a6439eb3beaba352d32c0f..9771ef0549c90f36301cb46ce5834746c9e07e11 100644 (file)
--- a/lib/MC/MCELFStreamer.cpp
+++ b/lib/MC/MCELFStreamer.cpp
@@ -86,6 +86,10 @@ void MCELFStreamer::EmitLabel(MCSymbol *Symbol) {
     MCELF::SetType(SD, ELF::STT_TLS);
 }
 
+void MCELFStreamer::EmitDebugLabel(MCSymbol *Symbol) {
+  EmitLabel(Symbol);
+}
+
 void MCELFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
   switch (Flag) {
   case MCAF_SyntaxUnified: return; // no-op here.

diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index f279e74e389833424f1dcdd4bad09850b99d575f..82ccdd4ac07c4ff3296fdc3fed86ac0a1fab21c4 100644 (file)
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -43,6 +43,7 @@ public:
 
   virtual void InitSections();
   virtual void EmitLabel(MCSymbol *Symbol);
+  virtual void EmitDebugLabel(MCSymbol *Symbol);
   virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
                                    MCSymbol *EHSymbol);
   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
@@ -130,6 +131,9 @@ void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
   SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
 }
 
+void MCMachOStreamer::EmitDebugLabel(MCSymbol *Symbol) {
+  EmitLabel(Symbol);
+}
 void MCMachOStreamer::EmitDataRegion(DataRegionData::KindTy Kind) {
   if (!getAssembler().getBackend().hasDataInCodeSupport())
     return;

diff --git a/lib/MC/MCNullStreamer.cpp b/lib/MC/MCNullStreamer.cpp
index f5ece10dc47872874e853fe598e6a05a6e8476bb..bb84c4f22fe484a46a08f5d56a72c5c0228c5399 100644 (file)
--- a/lib/MC/MCNullStreamer.cpp
+++ b/lib/MC/MCNullStreamer.cpp
@@ -35,7 +35,9 @@ namespace {
       assert(getCurrentSection() && "Cannot emit before setting section!");
       Symbol->setSection(*getCurrentSection());
     }
-
+    virtual void EmitDebugLabel(MCSymbol *Symbol) {
+      EmitLabel(Symbol);
+    }
     virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) {}
     virtual void EmitThumbFunc(MCSymbol *Func) {}
 

diff --git a/lib/MC/MCObjectStreamer.cpp b/lib/MC/MCObjectStreamer.cpp
index c69d76428cbcf2d3ecbb1f8f02d0b40d8d3e176e..4d6900f7c463e4b2b4562e03fb573b0bec36ef68 100644 (file)
--- a/lib/MC/MCObjectStreamer.cpp
+++ b/lib/MC/MCObjectStreamer.cpp
@@ -134,6 +134,10 @@ void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
   SD.setOffset(F->getContents().size());
 }
 
+void MCObjectStreamer::EmitDebugLabel(MCSymbol *Symbol) {
+  EmitLabel(Symbol);
+}
+
 void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
   int64_t IntValue;
   if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {

diff --git a/lib/MC/MCPureStreamer.cpp b/lib/MC/MCPureStreamer.cpp
index 1563bdd107fcaa814894e1db14a942e9b8781cdc..bb1f3d459a2d1fc13244b89ae9b63c5ada75948f 100644 (file)
--- a/lib/MC/MCPureStreamer.cpp
+++ b/lib/MC/MCPureStreamer.cpp
@@ -37,6 +37,7 @@ public:
 
   virtual void InitSections();
   virtual void EmitLabel(MCSymbol *Symbol);
+  virtual void EmitDebugLabel(MCSymbol *Symbol);
   virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
                             uint64_t Size = 0, unsigned ByteAlignment = 0);
   virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
@@ -134,6 +135,7 @@ void MCPureStreamer::EmitLabel(MCSymbol *Symbol) {
   SD.setOffset(F->getContents().size());
 }
 
+
 void MCPureStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
                                   uint64_t Size, unsigned ByteAlignment) {
   report_fatal_error("not yet implemented in pure streamer");

diff --git a/lib/MC/MCStreamer.cpp b/lib/MC/MCStreamer.cpp
index 047ab636ab7ee1149c094c30358eca5b7a5e3b43..6f0ada277c1b68ff05eb45101dd73a4001743697 100644 (file)
--- a/lib/MC/MCStreamer.cpp
+++ b/lib/MC/MCStreamer.cpp
@@ -195,6 +195,13 @@ void MCStreamer::EmitLabel(MCSymbol *Symbol) {
   LastSymbol = Symbol;
 }
 
+void MCStreamer::EmitDebugLabel(MCSymbol *Symbol) {
+  assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
+  assert(getCurrentSection() && "Cannot emit before setting section!");
+  Symbol->setSection(*getCurrentSection());
+  LastSymbol = Symbol;
+}
+
 void MCStreamer::EmitCompactUnwindEncoding(uint32_t CompactUnwindEncoding) {
   EnsureValidFrame();
   MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();

diff --git a/lib/MC/WinCOFFStreamer.cpp b/lib/MC/WinCOFFStreamer.cpp
index 359b388618e5262b43951ca0c86be0996840b3e7..d12201a6ca697c6ca35a0d72c41e5066960824ec 100644 (file)
--- a/lib/MC/WinCOFFStreamer.cpp
+++ b/lib/MC/WinCOFFStreamer.cpp
@@ -51,6 +51,7 @@ public:
 
   virtual void InitSections();
   virtual void EmitLabel(MCSymbol *Symbol);
+  virtual void EmitDebugLabel(MCSymbol *Symbol);
   virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
   virtual void EmitThumbFunc(MCSymbol *Func);
   virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
@@ -176,6 +177,9 @@ void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
   MCObjectStreamer::EmitLabel(Symbol);
 }
 
+void WinCOFFStreamer::EmitDebugLabel(MCSymbol *Symbol) {
+  EmitLabel(Symbol);
+}
 void WinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
   llvm_unreachable("not implemented");
 }

diff --git a/lib/Target/Mips/MCTargetDesc/MipsMCAsmInfo.cpp b/lib/Target/Mips/MCTargetDesc/MipsMCAsmInfo.cpp
index 9d67aa1856e3609e05315fa075a2445380ecfd72..d5ed8b13f5ad4fb5796656d8c8ec2097503b7b12 100644 (file)
--- a/lib/Target/Mips/MCTargetDesc/MipsMCAsmInfo.cpp
+++ b/lib/Target/Mips/MCTargetDesc/MipsMCAsmInfo.cpp
@@ -34,7 +34,7 @@ MipsMCAsmInfo::MipsMCAsmInfo(const Target &T, StringRef TT) {
   GPRel32Directive            = "\t.gpword\t";
   GPRel64Directive            = "\t.gpdword\t";
   WeakRefDirective            = "\t.weak\t";
-
+  DebugLabelSuffix            = "=.";
   SupportsDebugInformation = true;
   ExceptionsType = ExceptionHandling::DwarfCFI;
   HasLEB128 = true;

diff --git a/test/CodeGen/Mips/mips16ex.ll b/test/CodeGen/Mips/mips16ex.ll
new file mode 100644 (file)
index 0000000..ecb30b5
--- /dev/null
+++ b/test/CodeGen/Mips/mips16ex.ll
@@ -0,0 +1,87 @@
+; RUN: llc  -march=mipsel -mcpu=mips16 -relocation-model=pic -O3 < %s | FileCheck %s -check-prefix=16
+
+;16: $eh_func_begin0=.
+@.str = private unnamed_addr constant [7 x i8] c"hello\0A\00", align 1
+@_ZTIi = external constant i8*
+@.str1 = private unnamed_addr constant [15 x i8] c"exception %i \0A\00", align 1
+
+define i32 @main() {
+entry:
+  %retval = alloca i32, align 4
+  %exn.slot = alloca i8*
+  %ehselector.slot = alloca i32
+  %e = alloca i32, align 4
+  store i32 0, i32* %retval
+  %call = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([7 x i8]* @.str, i32 0, i32 0))
+  %exception = call i8* @__cxa_allocate_exception(i32 4) nounwind
+  %0 = bitcast i8* %exception to i32*
+  store i32 20, i32* %0
+  invoke void @__cxa_throw(i8* %exception, i8* bitcast (i8** @_ZTIi to i8*), i8* null) noreturn
+          to label %unreachable unwind label %lpad
+
+lpad:                                             ; preds = %entry
+  %1 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*)
+          catch i8* bitcast (i8** @_ZTIi to i8*)
+  %2 = extractvalue { i8*, i32 } %1, 0
+  store i8* %2, i8** %exn.slot
+  %3 = extractvalue { i8*, i32 } %1, 1
+  store i32 %3, i32* %ehselector.slot
+  br label %catch.dispatch
+
+catch.dispatch:                                   ; preds = %lpad
+  %sel = load i32* %ehselector.slot
+  %4 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*)) nounwind
+  %matches = icmp eq i32 %sel, %4
+  br i1 %matches, label %catch, label %eh.resume
+
+catch:                                            ; preds = %catch.dispatch
+  %exn = load i8** %exn.slot
+  %5 = call i8* @__cxa_begin_catch(i8* %exn) nounwind
+  %6 = bitcast i8* %5 to i32*
+  %exn.scalar = load i32* %6
+  store i32 %exn.scalar, i32* %e, align 4
+  %7 = load i32* %e, align 4
+  %call2 = invoke i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([15 x i8]* @.str1, i32 0, i32 0), i32 %7)
+          to label %invoke.cont unwind label %lpad1
+
+invoke.cont:                                      ; preds = %catch
+  call void @__cxa_end_catch() nounwind
+  br label %try.cont
+
+try.cont:                                         ; preds = %invoke.cont
+  ret i32 0
+
+lpad1:                                            ; preds = %catch
+  %8 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*)
+          cleanup
+  %9 = extractvalue { i8*, i32 } %8, 0
+  store i8* %9, i8** %exn.slot
+  %10 = extractvalue { i8*, i32 } %8, 1
+  store i32 %10, i32* %ehselector.slot
+  call void @__cxa_end_catch() nounwind
+  br label %eh.resume
+
+eh.resume:                                        ; preds = %lpad1, %catch.dispatch
+  %exn3 = load i8** %exn.slot
+  %sel4 = load i32* %ehselector.slot
+  %lpad.val = insertvalue { i8*, i32 } undef, i8* %exn3, 0
+  %lpad.val5 = insertvalue { i8*, i32 } %lpad.val, i32 %sel4, 1
+  resume { i8*, i32 } %lpad.val5
+
+unreachable:                                      ; preds = %entry
+  unreachable
+}
+
+declare i32 @printf(i8*, ...)
+
+declare i8* @__cxa_allocate_exception(i32)
+
+declare i32 @__gxx_personality_v0(...)
+
+declare void @__cxa_throw(i8*, i8*, i8*)
+
+declare i32 @llvm.eh.typeid.for(i8*) nounwind readnone
+
+declare i8* @__cxa_begin_catch(i8*)
+
+declare void @__cxa_end_catch()

diff --git a/tools/lto/LTOModule.cpp b/tools/lto/LTOModule.cpp
index a0533db480463ea4f00e3981422cc124934a8fd4..9d2f9c784838ddcba93965863dbc3477adc91034 100644 (file)
--- a/tools/lto/LTOModule.cpp
+++ b/tools/lto/LTOModule.cpp
@@ -745,6 +745,9 @@ namespace {
       Symbol->setSection(*getCurrentSection());
       markDefined(*Symbol);
     }
+    virtual void EmitDebugLabel(MCSymbol *Symbol) {
+      EmitLabel(Symbol);
+    }
     virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
       // FIXME: should we handle aliases?
       markDefined(*Symbol);