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author | Xi Wang <xi.wang@gmail.com> | 2013-05-19 08:13:09 -0400 |
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committer | Pekka Enberg <penberg@kernel.org> | 2013-05-19 15:45:33 +0300 |
commit | e33b721d954a0c59ca1c09e75ec0657e0c3e0391 (patch) | |
tree | e3a1589e8d1cde9bea5d11b498353657fd4d8169 | |
parent | 2afee5ceadcdfaefcb94f8d15291c977d0a990ec (diff) | |
download | sparse-e33b721d954a0c59ca1c09e75ec0657e0c3e0391.tar.gz |
sparse, llvm: improve pointer arithmetic handling
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.
Acked-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
-rw-r--r-- | sparse-llvm.c | 38 |
1 files changed, 26 insertions, 12 deletions
diff --git a/sparse-llvm.c b/sparse-llvm.c index 41e0ab7e..35629c4e 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; } |