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Use llvm TargetData to find object sizes, offsets.

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Previously, to compute the size of objects and the offsets of struct
elements within structs, we were using the trick of using getelementpointer 
with a NULL base pointer and then casting the result to an int32/64.
However, since we actually know the target we're compiling for at
compile time, we can use corresponding methods from TargetData to
get these values directly.

This mostly cleans up code, but may make some of the gather/scatter
lowering to loads/stores optimizations work better in the presence
of structures.
This commit is contained in:
Matt Pharr
2011-11-06 19:31:19 -08:00
parent 7a1ce558e9
commit f8eb100c60
5 changed files with 49 additions and 167 deletions
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24
ctx.cpp
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@@ -799,28 +799,6 @@ FunctionEmitContext::I1VecToBoolVec(llvm::Value *b) {
}
llvm::Value *
FunctionEmitContext::SizeOf(LLVM_TYPE_CONST llvm::Type *ty) {
// Emit code to compute the size of the given type using a GEP with a
// NULL base pointer, indexing one element of the given type, and
// casting the resulting 'pointer' to an int giving its size.
LLVM_TYPE_CONST llvm::Type *ptrType = llvm::PointerType::get(ty, 0);
llvm::Value *nullPtr = llvm::Constant::getNullValue(ptrType);
llvm::Value *index[1] = { LLVMInt32(1) };
#if defined(LLVM_3_0) || defined(LLVM_3_0svn) || defined(LLVM_3_1svn)
llvm::ArrayRef<llvm::Value *> arrayRef(&index[0], &index[1]);
llvm::Value *poffset = llvm::GetElementPtrInst::Create(nullPtr, arrayRef,
"offset_ptr", bblock);
#else
llvm::Value *poffset = llvm::GetElementPtrInst::Create(nullPtr, &index[0], &index[1],
"offset_ptr", bblock);
#endif
AddDebugPos(poffset);
llvm::Value *sizeOf = PtrToIntInst(poffset, LLVMTypes::Int64Type, "offset_int");
return sizeOf;
}
static llvm::Value *
lGetStringAsValue(llvm::BasicBlock *bblock, const char *s) {
llvm::Constant *sConstant = llvm::ConstantArray::get(*g->ctx, s);
@@ -2266,7 +2244,7 @@ FunctionEmitContext::LaunchInst(llvm::Value *callee,
int align = 4 * RoundUpPow2(g->target.nativeVectorWidth);
std::vector<llvm::Value *> allocArgs;
allocArgs.push_back(launchGroupHandlePtr);
allocArgs.push_back(SizeOf(argStructType));
allocArgs.push_back(g->target.SizeOf(argStructType));
allocArgs.push_back(LLVMInt32(align));
llvm::Value *voidmem = CallInst(falloc, NULL, allocArgs, "args_ptr");
llvm::Value *argmem = BitCastInst(voidmem, pt);