[cfe-commits] r44830 - in /cfe/trunk: CodeGen/CodeGenTypes.cpp test/CodeGen/struct-x86-darwin.c
Devang Patel
dpatel at apple.com
Mon Dec 10 16:49:18 PST 2007
Author: dpatel
Date: Mon Dec 10 18:49:18 2007
New Revision: 44830
URL: http://llvm.org/viewvc/llvm-project?rev=44830&view=rev
Log:
Add support to share llvm fields for bit-fields.
For example, struct { char a; short b:2; };
Modified:
cfe/trunk/CodeGen/CodeGenTypes.cpp
cfe/trunk/test/CodeGen/struct-x86-darwin.c
Modified: cfe/trunk/CodeGen/CodeGenTypes.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/CodeGen/CodeGenTypes.cpp?rev=44830&r1=44829&r2=44830&view=diff
==============================================================================
--- cfe/trunk/CodeGen/CodeGenTypes.cpp (original)
+++ cfe/trunk/CodeGen/CodeGenTypes.cpp Mon Dec 10 18:49:18 2007
@@ -65,6 +65,15 @@
return STy;
}
+ /// fixCursorPosition - When bit-field is followed by a normal field
+ /// then cursor position may require some adjustments. For example,
+ /// struct { char a; short b:2; char c; };
+ /// At the beginning of 'c' during layout, cursor position is 10.
+ /// However, only one llvm struct field is allocated and it is i8.
+ /// This happens because 'b' shares llvm field with 'a'.
+ /// Similar adjustment may be required if bit-field is last field.
+ void fixCursorPosition(const ASTRecordLayout &RL);
+
private:
CodeGenTypes &CGT;
llvm::Type *STy;
@@ -80,6 +89,7 @@
uint64_t CurrentFieldStart;
llvm::SmallVector<const FieldDecl *, 8> FieldDecls;
std::vector<const llvm::Type*> LLVMFields;
+ llvm::SmallVector<uint64_t, 8> Offsets;
};
}
@@ -431,8 +441,23 @@
else {
// This is - struct { char A; short CurrentField:2; };
// Use one of the previous filed to access current field.
- assert(0
- && "Incomplete support for struct { char a; short b:2;}; ");
+ bool FoundPrevField = false;
+ unsigned TotalOffsets = Offsets.size();
+ uint64_t TySize = CGT.getTargetData().getABITypeSizeInBits(Ty);
+ for (unsigned i = TotalOffsets; i != 0; --i) {
+ uint64_t O = Offsets[i - 1];
+ if (O % TySize == 0) {
+ // This is appropriate llvm field to share access.
+ FoundPrevField = true;
+ CurrentFieldStart = O % TySize;
+ unsigned FieldBegin = Cursor - (O % TySize);
+ unsigned FieldEnd = TySize - (FieldBegin + BitFieldSize);
+ Cursor += BitFieldSize;
+ CGT.addFieldInfo(FD, FieldNo, FieldBegin, FieldEnd, i);
+ }
+ }
+ assert(FoundPrevField &&
+ "Unable to find a place for bitfield in struct layout");
}
}
} else if (ExtraBits >= BitFieldSize) {
@@ -458,10 +483,20 @@
}
} else {
ExtraBits = 0;
+ // FD is not a bitfield. If prev field was a bit field then it may have
+ // positioned cursor such that it needs adjustment now.
+ if (Cursor % 8 != 0)
+ fixCursorPosition(RL);
+
const llvm::Type *Ty = CGT.ConvertType(FD->getType());
addLLVMField(Ty, CGT.getTargetData().getABITypeSizeInBits(Ty), FD, 0, 0);
}
}
+
+ // At the end of structure, cursor should point to end of the strucutre.
+ // This may not happen automatically if last field is a bit-field.
+ fixCursorPosition(RL);
+
STy = llvm::StructType::get(LLVMFields);
}
@@ -490,6 +525,7 @@
// combining consequetive padding fields.
addPaddingFields(Cursor % AlignmentInBits);
+ Offsets.push_back(Cursor);
CurrentFieldStart = Cursor;
Cursor += Size;
LLVMFields.push_back(Ty);
@@ -533,3 +569,25 @@
STy = llvm::StructType::get(Fields);
}
+/// fixCursorPosition - When bit-field is followed by a normal field
+/// then cursor position may require some adjustments. For example,
+/// struct { char a; short b:2; char c; };
+/// At the beginning of 'c' during layout, cursor position is 10.
+/// However, only one llvm struct field is allocated so far is i8.
+/// This happens because 'b' shares llvm field with 'a'.
+/// Similar adjustment may be required if last record field is a bit-field.
+void RecordOrganizer::fixCursorPosition(const ASTRecordLayout &RL) {
+ uint64_t llvmSize = 0;
+ for(std::vector<const llvm::Type*>::iterator LI = LLVMFields.begin(),
+ LE = LLVMFields.end(); LI != LE; ++LI) {
+ const llvm::Type *Ty = *LI;
+ llvmSize += CGT.getTargetData().getABITypeSizeInBits(Ty);
+ }
+ Cursor = llvmSize;
+ unsigned llvmSizeBytes = llvmSize/8;
+ unsigned StructAlign = RL.getAlignment() / 8;
+ if (llvmSizeBytes % StructAlign) {
+ unsigned StructPadding = StructAlign - (llvmSizeBytes % StructAlign);
+ addPaddingFields(StructPadding*8);
+ }
+}
Modified: cfe/trunk/test/CodeGen/struct-x86-darwin.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/struct-x86-darwin.c?rev=44830&r1=44829&r2=44830&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/struct-x86-darwin.c (original)
+++ cfe/trunk/test/CodeGen/struct-x86-darwin.c Mon Dec 10 18:49:18 2007
@@ -3,7 +3,9 @@
// RUN: grep "STest2 = type { i16, i16, i32, i32 }" %t1 &&
// RUN: grep "STest3 = type { i8, i8, i16, i32 }" %t1 &&
// RUN: grep "STestB1 = type { i8, i8 }" %t1 &&
-// RUN: grep "STestB2 = type { i8, i8, i8 }" %t1
+// RUN: grep "STestB2 = type { i8, i8, i8 }" %t1 &&
+// RUN: grep "STestB3 = type { i8, i8 }" %t1 &&
+// RUN: grep "STestB4 = type { i8, i8, i8, i8 }" %t1
// Test struct layout for x86-darwin target
// FIXME : Enable this test for x86-darwin only. At the moment clang hard codes
// x86-darwin as the target
@@ -14,7 +16,9 @@
// Bitfields
struct STestB1 {char a; char b:2; } stb1;
-struct STestB2 {char a; char b:5; char c:4} stb2;
+struct STestB2 {char a; char b:5; char c:4; } stb2;
+struct STestB3 {char a; char b:2; } stb3;
+struct STestB4 {char a; short b:2; char c; } stb4;
//struct STestB {int a:1; char b; int c:13 } stb;
// Packed struct STestP1 {char a; short b; int c; } __attribute__((__packed__)) stp1;
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