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.

llvm-svn: 51224

clang/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 @@ RValue CodeGenFunction::EmitLoadOfBitfieldLValue(LValue LV,
   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 @@ void CodeGenFunction::EmitStoreThroughBitfieldLValue(RValue Src, LValue Dst,
   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 @@ LValue CodeGenFunction::EmitLValueForField(llvm::Value* BaseValue,
   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();

clang/test/CodeGen/bool-bitfield.c

@@ -0,0 +1,54 @@
+// RUN: clang -emit-llvm %s
+
+// From GCC PR19331
+struct SysParams
+{
+ unsigned short tag;
+ unsigned short version;
+ unsigned int seqnum;
+ int contrast;
+ int igain_1, igain_2;
+ int oattn_1, oattn_2;
+ int max_out_vltg_1, max_out_vltg_2;
+ int max_mains_current;
+ int meters_mode;
+ int input_select;
+ _Bool input_parallelch2:1;
+ _Bool cliplmt_ch1:1;
+ _Bool cliplmt_ch2:1;
+ _Bool gate_ch1:1;
+ _Bool gate_ch2:1;
+ _Bool mute_ch1:1;
+ _Bool mute_ch2:1;
+ _Bool brownout:1;
+ _Bool power_on:1;
+ _Bool pwrup_mute:1;
+ _Bool keylock:1;
+ _Bool dsp_ch1:1;
+ _Bool dsp_ch2:1;
+ int dsp_preset;
+ long unlock_code;
+};
+extern struct SysParams params;
+
+void foo(void *);
+void kcmd_setParams(void)
+{
+ struct {
+  unsigned char igain_1;
+  unsigned char igain_2;
+  unsigned char max_out_vltg_1;
+  unsigned char max_out_vltg_2;
+  unsigned char max_imains;
+  unsigned char cliplmt_ch1:1;
+  unsigned char cliplmt_ch2:1;
+  unsigned char gate_ch1:1;
+  unsigned char gate_ch2:1;
+ } msg;
+ foo(&msg);
+ params.cliplmt_ch1 = msg.cliplmt_ch1;
+ params.cliplmt_ch2 = msg.cliplmt_ch2;
+ params.gate_ch1 = msg.gate_ch1;
+ params.gate_ch2 = msg.gate_ch2;
+}
+