Converting pointers to integers for pointer arithmetic effectively
disables pointer analysis and future optimizations. A better way is to
use LLVM's GEP, by converting pointers to `char *' rather than integers.
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Acked-by: Jonathan Neuschäfer <j.neuschaefer@xxxxxxx>
Signed-off-by: Xi Wang <xi.wang@xxxxxxxxx>
---
calc_gep() may be useful for fixing array access as well.
---
sparse-llvm.c | 38 ++++++++++++++++++++++++++------------
1 file changed, 26 insertions(+), 12 deletions(-)
diff --git a/sparse-llvm.c b/sparse-llvm.c
index 41e0ab7..02f43f7 100644
--- a/sparse-llvm.c
+++ b/sparse-llvm.c
@@ -370,6 +370,22 @@ static LLVMValueRef pseudo_to_value(struct function *fn, struct instruction *ins
return result;
}
+static LLVMValueRef calc_gep(LLVMBuilderRef builder, LLVMValueRef base, LLVMValueRef off)
+{
+ LLVMTypeRef type = LLVMTypeOf(base);
+ unsigned int as = LLVMGetPointerAddressSpace(type);
+ LLVMTypeRef bytep = LLVMPointerType(LLVMInt8Type(), as);
+ LLVMValueRef addr;
+
+ /* convert base to char* type */
+ base = LLVMBuildPointerCast(builder, base, bytep, "");
+ /* addr = base + off */
+ addr = LLVMBuildInBoundsGEP(builder, base, &off, 1, "");
+ /* convert back to the actual pointer type */
+ addr = LLVMBuildPointerCast(builder, addr, type, "");
+ return addr;
+}
+
static LLVMRealPredicate translate_fop(int opcode)
{
static const LLVMRealPredicate trans_tbl[] = {
@@ -544,23 +560,21 @@ static void output_op_ret(struct function *fn, struct instruction *insn)
static LLVMValueRef calc_memop_addr(struct function *fn, struct instruction *insn)
{
LLVMTypeRef int_type, addr_type;
- LLVMValueRef src_p, src_i, ofs_i, addr_i, addr;
+ LLVMValueRef src, off, addr;
+ unsigned int as;
/* int type large enough to hold a pointer */
int_type = LLVMIntType(bits_in_pointer);
+ off = LLVMConstInt(int_type, insn->offset, 0);
- /* convert to integer, add src + offset */
- src_p = pseudo_to_value(fn, insn, insn->src);
- src_i = LLVMBuildPtrToInt(fn->builder, src_p, int_type, "src_i");
-
- ofs_i = LLVMConstInt(int_type, insn->offset, 0);
- addr_i = LLVMBuildAdd(fn->builder, src_i, ofs_i, "addr_i");
-
- addr_type = LLVMPointerType(insn_symbol_type(fn->module, insn), 0);
-
- /* convert address back to pointer */
- addr = LLVMBuildIntToPtr(fn->builder, addr_i, addr_type, "addr");
+ /* convert src to the effective pointer type */
+ src = pseudo_to_value(fn, insn, insn->src);
+ as = LLVMGetPointerAddressSpace(LLVMTypeOf(src));
+ addr_type = LLVMPointerType(insn_symbol_type(fn->module, insn), as);
+ src = LLVMBuildPointerCast(fn->builder, src, addr_type, "");
+ /* addr = src + off */
+ addr = calc_gep(fn->builder, src, off);
return addr;
}
--
1.8.1.2
--
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