Fix the code that was WRONG.

The registers are placed into the saved registers list in the reverse order,
which is why the original loop was written to loop backwards.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148064 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 208 insertions, 13 deletions

diff --git a/docs/LangRef.html b/docs/LangRef.html
index 2799083..6881620 100644
--- a/docs/LangRef.html
+++ b/docs/LangRef.html
@@ -106,6 +106,11 @@
           <li><a href="#fpaccuracy">'<tt>fpaccuracy</tt>' Metadata</a></li>
         </ol>
       </li>
+      <li><a href="#module_flags">Module Flags Metadata</a>
+        <ol>
+          <li><a href="#objc_metadata">Objective-C Metadata</a></li>
+        </ol>
+      </li>
     </ol>
   </li>
   <li><a href="#intrinsic_globals">Intrinsic Global Variables</a>
@@ -3026,6 +3031,138 @@ call void @llvm.dbg.value(metadata !24, i64 0, metadata !25)
 
 </div>
 
+<!-- ======================================================================= -->
+<h3>
+  <a name="module_flags">Module Flags Metadata</a>
+</h3>
+ 
+<div>
+
+<p>Occasionally, the front-end needs to transmit data to the linker which
+   affects its behavior. The LLVM IR isn't sufficient to transmit this
+   information, so one should use the <tt>llvm.module.flags</tt> named
+   metadata.</p>
+
+<p>The <tt>llvm.module.flags</tt> metadata is a named metadata, whose elements
+   consist of metadata triplets. For example:</p>
+
+<pre class="doc_code">
+!0 = metadata !{ i32 0, metadata !"foo", i32 1 }
+!1 = metadata !{ i32 1, metadata !"bar", i32 37 }
+
+!llvm.module.flags = !{ !0, !1 }
+</pre>
+
+<p>The first field specifies the behavior of the linker upon encountering two of
+   the same values. Behavior could range from: emitting an error if some of the
+   modules' flags disagree, emitting a warning, etc. The second field is the
+   name of the metadata. The third field is the value of the metadata.</p>
+
+<p>When two modules are linked together, the <tt>llvm.module.flags</tt> metadata
+   are unioned together.</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<h4>
+  <a name="objc_metadata">Objective-C Metadata</a>
+</h4>
+ 
+<div>
+
+<p>The following module flags are used to convey Objective-C metadata to the
+   linker.</p>
+
+<table border="1" cellspacing="0" cellpadding="4">
+  <tbody>
+    <tr>
+      <th>Value</th>
+      <th>Behavior</th>
+    </tr>
+    <tr>
+      <td>1</td>
+      <td align="left">
+        <dl>
+          <dt><tt>Error</tt></dt>
+          <dd>Causes the linker to emit an error when two values disagree.</dd>
+        </dl>
+      </td>
+    </tr>
+    <tr>
+      <td>2</td>
+      <td align="left">
+        <dl>
+          <dt><tt>Require</tt></dt>
+          <dd>Causes the linker to emit an error when the specified value is not
+              present.</dd>
+        </dl>
+      </td>
+    </tr>
+    <tr>
+      <td>3</td>
+      <td align="left">
+        <dl>
+          <dt><tt>Override</tt></dt>
+          <dd>Causes the linker to use the specified value if the two values
+              disagree. It's an error if two pieces of the same metadata have
+              the <tt>Override</tt> behavior but different values.</dd>
+        </dl>
+      </td>
+    </tr>
+  </tbody>
+</table>
+
+<p>The names are:</p>
+
+<ul>
+  <li><tt>Objective-C Version</tt></li>
+  <li><tt>Objective-C Garbage Collection</tt></li>
+  <li><tt>Objective-C GC Only</tt></li>
+  <li><tt>Objective-C Image Info Section</tt></li>
+</ul>
+
+<p>
+
+<p>Here is an example of how to use the Objective-C metadata:</p>
+
+<pre class="doc_code">
+<u>Module A</u>
+!0 = metadata !{ i32 1, metadata !"Objective-C Version", i32 2 }
+!1 = metadata !{ i32 1, metadata !"Objective-C Garbage Collection", i32 2 }
+!2 = metadata !{ i32 1, metadata !"Objective-C Image Info Section",
+                 metadata !"__DATA, __objc_imageinfo, regular, no_dead_strip" }
+!llvm.module.flags = !{ !0, !1, !2 }
+
+<u>Module B</u>
+!0 = metadata !{ i32 1, metadata !"Objective-C Version", i32 2 }
+!1 = metadata !{ i32 1, metadata !"Objective-C Garbage Collection", i32 2 }
+!2 = metadata !{ i32 1, metadata !"Objective-C GC Only", i32 4 }
+!3 = metadata !{ i32 1, metadata !"Objective-C Image Info Section",
+                 metadata !"__DATA, __objc_imageinfo, regular, no_dead_strip" }
+!4 = metadata !{ i32 2, metadata !"Objective-C GC Only",
+  metadata !{
+    metadata !"Objective-C Garbage Collection", i32 2
+  }
+}
+!llvm.module.flags = !{ !0, !1, !2, !3, !4 }
+
+<u>Linked Module</u>
+!0 = metadata !{ i32 1, metadata !"Objective-C Version", i32 2 }
+!1 = metadata !{ i32 3, metadata !"Objective-C Garbage Collection", i32 2 }
+!2 = metadata !{ i32 1, metadata !"Objective-C GC Only", i32 4 }
+!3 = metadata !{ i32 1, metadata !"Objective-C Image Info Section",
+                 metadata !"__DATA, __objc_imageinfo, regular, no_dead_strip" }
+!4 = metadata !{ i32 2, metadata !"Objective-C GC Only",
+  metadata !{
+    metadata !"Objective-C Garbage Collection", i32 2
+  }
+}
+!llvm.module.flags = !{ !0, !1, !2, !3, !4 }
+</pre>
+
+
+</div>
+
 </div>
 
 <!-- *********************************************************************** -->
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 82860c2..1b15cdc 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -930,6 +930,71 @@ bool AsmPrinter::doFinalization(Module &M) {
     if (const MCSection *S = MAI->getNonexecutableStackSection(OutContext))
       OutStreamer.SwitchSection(S);
 
+  // If we have module flags, then emit them.
+  NamedMDNode *ModFlags = M.getNamedMetadata("llvm.module.flags");
+  if (ModFlags) {
+    const char *ObjCGCName = "Objective-C Garbage Collection";
+    const char *ObjCGCOnlyName = "Objective-C GC Only";
+    const char *ObjCImageInfoVersion = "Objective-C Image Info Version";
+    const char *ObjCImageInfoSec = "Objective-C Image Info Section";
+
+    MDNode *GC = 0;
+    MDNode *GCOnly = 0;
+    MDNode *ImageInfoVersion = 0;
+    MDNode *ImageInfoSec = 0;
+
+    for (unsigned I = 0, E = ModFlags->getNumOperands(); I != E; ++I) {
+      MDNode *MD = ModFlags->getOperand(I);
+      unsigned Behavior = cast<ConstantInt>(MD->getOperand(0))->getZExtValue();
+      (void) Behavior;
+      MDString *Str = cast<MDString>(MD->getOperand(1));
+
+      if (Str->getString() == ObjCImageInfoVersion) {
+        assert(Behavior == 1 && "Invalid behavior for module flag!");
+        ImageInfoVersion = MD;
+      } else if (Str->getString() == ObjCGCName) {
+        assert((Behavior == 1 || Behavior == 3) &&
+               "Invalid behavior for module flag!");
+        GC = MD;
+      } else if (Str->getString() == ObjCGCOnlyName) {
+        if (Behavior == 2) continue; // Ignore the 'require' clause.
+        GCOnly = MD;
+      } else if (Str->getString() == ObjCImageInfoSec) {
+        assert(Behavior == 1 && "Invalid behavior for module flag!");
+        ImageInfoSec = MD;
+      }
+    }
+
+    if (ImageInfoVersion || GC || GCOnly || ImageInfoSec) {
+      // FIXME: Duh!
+      unsigned version = 0;
+      unsigned flags = 0;
+
+      version =
+        cast<ConstantInt>(ImageInfoVersion->getOperand(2))->getZExtValue();
+      if (GC)
+        flags |= cast<ConstantInt>(GC->getOperand(2))->getZExtValue();
+      if (GCOnly)
+        flags |= cast<ConstantInt>(GCOnly->getOperand(2))->getZExtValue();
+
+      Type *Int32Ty = Type::getInt32Ty(M.getContext());
+      Constant *values[2] = {
+        ConstantInt::get(Int32Ty, version),
+        ConstantInt::get(Int32Ty, flags)
+      };
+      ArrayType *AT = ArrayType::get(Int32Ty, 2);
+      StringRef Sec = cast<MDString>(ImageInfoSec->getOperand(2))->getString();
+
+      GlobalVariable *GV =
+        cast<GlobalVariable>(M.getOrInsertGlobal("L_OBJC_IMAGE_INFO", AT));
+      GV->setConstant(true);
+      GV->setSection(Sec);
+      GV->setInitializer(ConstantArray::get(AT, values));
+
+      EmitGlobalVariable(GV);
+    }
+  }
+
   // Allow the target to emit any magic that it wants at the end of the file,
   // after everything else has gone out.
   EmitEndOfAsmFile(M);
diff --git a/lib/Target/X86/X86FrameLowering.cpp b/lib/Target/X86/X86FrameLowering.cpp
index e5f6752..5dfc0bb 100644
--- a/lib/Target/X86/X86FrameLowering.cpp
+++ b/lib/Target/X86/X86FrameLowering.cpp
@@ -455,26 +455,19 @@ encodeCompactUnwindRegistersWithFrame(unsigned SavedRegs[CU_NUM_SAVED_REGS],
   };
   const unsigned *CURegs = (Is64Bit ? CU64BitRegs : CU32BitRegs);
 
-  // FIXME: The code below is WRONG and breaks tests on i386, see
-  // SingleSource/Regression/C++/EH/ctor_dtor_count.exec
-  // SingleSource/Regression/C++/EH/exception_spec_test.exec
-  // SingleSource/Regression/C++/EH/function_try_block.exec
-  // SingleSource/Regression/C++/EH/throw_rethrow_test.exec
-  return ~0U;
-
   // Encode the registers in the order they were saved, 3-bits per register. The
-  // registers are numbered from 1 to 6.
+  // registers are numbered from 1 to CU_NUM_SAVED_REGS.
   uint32_t RegEnc = 0;
-  for (int I = 0; I != 6; ++I) {
+  for (int I = CU_NUM_SAVED_REGS, Idx = 0; I != -1; --I) {
     unsigned Reg = SavedRegs[I];
-    if (Reg == 0) break;
+    if (Reg == 0) continue;
+
     int CURegNum = getCompactUnwindRegNum(CURegs, Reg);
-    if (CURegNum == -1)
-      return ~0U;
+    if (CURegNum == -1) return ~0U;
 
     // Encode the 3-bit register number in order, skipping over 3-bits for each
     // register.
-    RegEnc |= (CURegNum & 0x7) << ((5 - I) * 3);
+    RegEnc |= (CURegNum & 0x7) << (Idx++ * 3);
   }
 
   assert((RegEnc & 0x3FFFF) == RegEnc && "Invalid compact register encoding!");