[cfe-commits] r50769 - in /cfe/trunk: lib/CodeGen/CodeGenTypes.cpp test/CodeGen/bitfield-init.c

[Devang Patel]

Author: dpatel
Date: Tue May  6 14:57:59 2008
New Revision: 50769

URL: http://llvm.org/viewvc/llvm-project?rev=50769&view=rev
Log:
Fix PR2101 - Codegen crash during bitfield initialization.

Added:
    cfe/trunk/test/CodeGen/bitfield-init.c
Modified:
    cfe/trunk/lib/CodeGen/CodeGenTypes.cpp

Modified: cfe/trunk/lib/CodeGen/CodeGenTypes.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenTypes.cpp?rev=50769&r1=50768&r2=50769&view=diff

==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenTypes.cpp (original)
+++ cfe/trunk/lib/CodeGen/CodeGenTypes.cpp Tue May  6 14:57:59 2008
@@ -521,7 +521,28 @@
   unsigned StructAlign = RL.getAlignment();
   if (llvmSize % StructAlign) {
     unsigned StructPadding = StructAlign - (llvmSize % StructAlign);
-    addPaddingFields(llvmSize + StructPadding);
+    bool needStructPadding = true;
+    if (!LLVMFields.empty()) {
+      const llvm::Type *LastFieldType = LLVMFields.back();
+      const llvm::Type *LastFieldDeclType = 
+        CGT.ConvertTypeRecursive(FieldDecls.back()->getType());
+      if (LastFieldType != LastFieldDeclType) {
+        unsigned LastFieldTypeSize = 
+          CGT.getTargetData().getABITypeSizeInBits(LastFieldType);
+        unsigned LastFieldDeclTypeSize = 
+          CGT.getTargetData().getABITypeSizeInBits(LastFieldDeclType);
+        if (LastFieldDeclTypeSize > LastFieldTypeSize
+            && StructPadding == (LastFieldDeclTypeSize - LastFieldTypeSize)) {
+          // Replace last LLVMField with a LastFieldDeclType field will 
+          // to avoid extra padding fields.
+          LLVMFields.pop_back();
+          LLVMFields.push_back(LastFieldDeclType);
+          needStructPadding = false;
+        }
+      }
+    }
+    if (needStructPadding)
+      addPaddingFields(llvmSize + StructPadding);
   }
 
   STy = llvm::StructType::get(LLVMFields);
@@ -533,8 +554,13 @@
   assert(WaterMark >= llvmSize && "Invalid padding Field");
   unsigned RequiredBits = WaterMark - llvmSize;
   unsigned RequiredBytes = (RequiredBits + 7) / 8;
-  for (unsigned i = 0; i != RequiredBytes; ++i)
-    addLLVMField(llvm::Type::Int8Ty, true);
+  if (RequiredBytes == 1)
+    // This is a bitfield that is using few bits from this byte.
+    // It is not a padding field.
+    addLLVMField(llvm::Type::Int8Ty, false);
+  else
+    for (unsigned i = 0; i != RequiredBytes; ++i)
+      addLLVMField(llvm::Type::Int8Ty, true);
 }
 
 /// addLLVMField - Add llvm struct field that corresponds to llvm type Ty.

Added: cfe/trunk/test/CodeGen/bitfield-init.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/bitfield-init.c?rev=50769&view=auto

==============================================================================
--- cfe/trunk/test/CodeGen/bitfield-init.c (added)
+++ cfe/trunk/test/CodeGen/bitfield-init.c Tue May  6 14:57:59 2008
@@ -0,0 +1,4 @@
+// RUN: clang %s -emit-llvm 
+typedef struct { unsigned int i: 1; } c;
+const c d = { 1 };
+