From: Bill Wendling <isanbard@gmail.com>
Date: Thu, 10 Sep 2009 02:07:37 +0000 (+0000)
Subject: Don't hardcode the TType format size. In fact, rework the code so that it's more
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=fe220285b5ef1e4480ddd7f7c8bb182b88a33b16;p=oota-llvm.git

Don't hardcode the TType format size. In fact, rework the code so that it's more
like what GCC outputs. The mysterious code to insert padding wasn't in GCC at
all. I modified the TType base offset code to calculate the offset like GCC
does, though.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81424 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/AsmPrinter/DwarfException.cpp b/lib/CodeGen/AsmPrinter/DwarfException.cpp
index b4cfc267d9f..45d8676b4d2 100644
--- a/lib/CodeGen/AsmPrinter/DwarfException.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfException.cpp
@@ -617,53 +617,11 @@ void DwarfException::EmitExceptionTable() {
   }
 
   // Type infos.
-  // FIXME: Don't hardcode. Should be TType's format encoding size.
-  unsigned TypeInfoSize = SizeOfEncodedValue(dwarf::DW_EH_PE_absptr);
-  unsigned SizeTypes = TypeInfos.size() * TypeInfoSize;
-
-  unsigned TypeOffset = sizeof(int8_t) +   // Call site format
-    MCAsmInfo::getULEB128Size(SizeSites) + // Call-site table length
-    SizeSites + SizeActions + SizeTypes;
-
-  unsigned TotalSize = sizeof(int8_t) + // LPStart format
-                       sizeof(int8_t) + // TType format
-       (HaveTTData ?
-          MCAsmInfo::getULEB128Size(TypeOffset) : 0) + // TType base offset
-                       TypeOffset;
-
-  unsigned SizeAlign = (4 - TotalSize) & 3;
-
-  // Begin the exception table.
   const MCSection *LSDASection = Asm->getObjFileLowering().getLSDASection();
-  Asm->OutStreamer.SwitchSection(LSDASection);
-  Asm->EmitAlignment(2, 0, 0, false);
-  O << "GCC_except_table" << SubprogramCount << ":\n";
-
-  for (unsigned i = 0; i != SizeAlign; ++i) {
-    Asm->EmitInt8(0);
-    Asm->EOL("Padding");
-  }
+  unsigned TTypeFormat;
 
-  EmitLabel("exception", SubprogramCount);
-  if (IsSJLJ) {
-    SmallString<16> LSDAName;
-    raw_svector_ostream(LSDAName) << MAI->getPrivateGlobalPrefix() <<
-      "_LSDA_" << Asm->getFunctionNumber();
-    O << LSDAName.str() << ":\n";
-  }
-
-  // Emit the header.
-  Asm->EmitInt8(dwarf::DW_EH_PE_omit);
-  Asm->EOL("@LPStart format", dwarf::DW_EH_PE_omit);
-
-  // For SjLj exceptions, if there is no TypeInfo, then we just explicitly
-  // say that we're omitting that bit.
-  // FIXME: does this apply to Dwarf also? The above #if 0 implies yes?
   if (!HaveTTData) {
-    // If there are no typeinfos or filters, there is nothing to emit, optimize
-    // by specifying the "omit" encoding.
-    Asm->EmitInt8(dwarf::DW_EH_PE_omit);
-    Asm->EOL("@TType format", dwarf::DW_EH_PE_omit);
+    TTypeFormat = dwarf::DW_EH_PE_omit;
   } else {
     // Okay, we have actual filters or typeinfos to emit.  As such, we need to
     // pick a type encoding for them.  We're about to emit a list of pointers to
@@ -689,19 +647,61 @@ void DwarfException::EmitExceptionTable() {
     // somewhere.  This predicate should be moved to a shared location that is
     // in target-independent code.
     //
-    unsigned TTypeFormat;
-
     if (LSDASection->getKind().isWriteable() ||
         Asm->TM.getRelocationModel() == Reloc::Static)
       TTypeFormat = dwarf::DW_EH_PE_absptr;
     else
       TTypeFormat = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
         dwarf::DW_EH_PE_sdata4;
+  }
+
+  // Begin the exception table.
+  Asm->OutStreamer.SwitchSection(LSDASection);
+  Asm->EmitAlignment(2, 0, 0, false);
+
+  O << "GCC_except_table" << SubprogramCount << ":\n";
+  EmitLabel("exception", SubprogramCount);
+
+  if (IsSJLJ) {
+    SmallString<16> LSDAName;
+    raw_svector_ostream(LSDAName) << MAI->getPrivateGlobalPrefix() <<
+      "_LSDA_" << Asm->getFunctionNumber();
+    O << LSDAName.str() << ":\n";
+  }
+
+  // Emit the header.
+  Asm->EmitInt8(dwarf::DW_EH_PE_omit);
+  Asm->EOL("@LPStart format", dwarf::DW_EH_PE_omit);
+
+  // For SjLj exceptions, if there is no TypeInfo, then we just explicitly
+  // say that we're omitting that bit.
+  Asm->EmitInt8(TTypeFormat);
+  Asm->EOL("@TType format", TTypeFormat);
+
+  if (HaveTTData) {
+    unsigned TypeFormatSize = SizeOfEncodedValue(TTypeFormat);
+    unsigned SizeTypes = TypeInfos.size() * TypeFormatSize;
+    unsigned BeforeOffset = 2;
+    unsigned TypeOffset = sizeof(int8_t) +   // Call site format
+      MCAsmInfo::getULEB128Size(SizeSites) + // Call-site table length
+      SizeSites + SizeActions + SizeTypes;
+    unsigned Offset = TypeOffset;
+    unsigned LastOffset = 0;
+
+    while (Offset != LastOffset) {
+      LastOffset = Offset;
+      unsigned Size = MCAsmInfo::getULEB128Size(Offset);
+      unsigned Pad = BeforeOffset + Size + TypeOffset;
+
+      if (Pad % TypeFormatSize)
+        Pad = TypeFormatSize - (Pad % TypeFormatSize);
+      else
+        Pad = 0;
 
-    Asm->EmitInt8(TTypeFormat);
-    Asm->EOL("@TType format", TTypeFormat);
+      Offset = TypeOffset + Pad;
+    }
 
-    Asm->EmitULEB128Bytes(TypeOffset);
+    Asm->EmitULEB128Bytes(Offset);
     Asm->EOL("@TType base offset");
   }