commit 316bb1b9eb9dc3da60e930f50c9b7578411d4966
author Eli Friedman <eli.friedman@gmail.com> Sat May 17 20:03:47 2008 +0000
committer Eli Friedman <eli.friedman@gmail.com> Sat May 17 20:03:47 2008 +0000
tree 42ea2358ffb8a4546b5e7aa0e9b08f02113099df
parent 489ecd59eff2602744cbd5089c48ad0d77963dfa

Fix support for _Bool bitfields. The issue is that the bitfield width 
used for _Bool is not the same as the primitive width (which for _Bool 
is 1 bit).  The load and store changes add some casts to make the 
types consistent.  The EmitLValue changes make sure that the pointer is 
of an appropriate type for loading the bitfield.

This isn't perfect, but it's an improvement, and getting everything 
right depends on actually laying out structs in an ABI-compliant way.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@51224 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CGExpr.cpp

diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index d679107..840ed43 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -14,11 +14,13 @@
 #include "CodeGenFunction.h"
 #include "CodeGenModule.h"
 #include "clang/AST/AST.h"
+#include "clang/Basic/TargetInfo.h"
 #include "llvm/Constants.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/Function.h"
 #include "llvm/GlobalVariable.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Target/TargetData.h"
 using namespace clang;
 using namespace CodeGen;
 
@@ -175,6 +177,11 @@
   V = LV.isBitfieldSigned() ?
     Builder.CreateAShr(V, ShAmt, "tmp") :
     Builder.CreateLShr(V, ShAmt, "tmp");
+
+  // The bitfield type and the normal type differ when the storage sizes
+  // differ (currently just _Bool).
+  V = Builder.CreateIntCast(V, ConvertType(ExprType), false, "tmp");
+
   return RValue::get(V);
 }
 
@@ -280,13 +287,18 @@
   unsigned short StartBit = Dst.getBitfieldStartBit();
   unsigned short BitfieldSize = Dst.getBitfieldSize();
   llvm::Value *Ptr = Dst.getBitfieldAddr();
-  const llvm::Type *EltTy =
-    cast<llvm::PointerType>(Ptr->getType())->getElementType();
-  unsigned EltTySize = EltTy->getPrimitiveSizeInBits();
 
   llvm::Value *NewVal = Src.getScalarVal();
   llvm::Value *OldVal = Builder.CreateLoad(Ptr, "tmp");
 
+  // The bitfield type and the normal type differ when the storage sizes
+  // differ (currently just _Bool).
+  const llvm::Type *EltTy = OldVal->getType();
+  unsigned EltTySize = CGM.getTargetData().getABITypeSizeInBits(EltTy);
+
+  NewVal = Builder.CreateIntCast(NewVal, EltTy, false, "tmp");
+
+  // Move the bits into the appropriate location
   llvm::Value *ShAmt = llvm::ConstantInt::get(EltTy, StartBit);
   NewVal = Builder.CreateShl(NewVal, ShAmt, "tmp");
 
@@ -531,7 +543,11 @@
   if (!Field->isBitField()) {
     V = Builder.CreateStructGEP(BaseValue, idx, "tmp");
   } else {
-    const llvm::Type *FieldTy = ConvertType(Field->getType());
+    // FIXME: CodeGenTypes should expose a method to get the appropriate
+    // type for FieldTy (the appropriate type is ABI-dependent).
+    unsigned EltTySize =
+      CGM.getTargetData().getABITypeSizeInBits(ConvertType(Field->getType()));
+    const llvm::Type *FieldTy = llvm::IntegerType::get(EltTySize);
     const llvm::PointerType *BaseTy =
       cast<llvm::PointerType>(BaseValue->getType());
     unsigned AS = BaseTy->getAddressSpace();