authorgravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2020-03-17 19:45:59-04:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2020-03-19 09:53:54-04:00
log2b4134459d468812ac106c124ee6fa5f5e8b9574
treeb25a3da862251ca353cdf3c8272dd498ffeb5ef9
parent8ea0a00f406bb04c08a8fa4471c3a3895f82b24a
signaturelock-open Commit is signed but in an unrecognized format.

fix alignment when slicing with comptime start and end index


2 files changed, 54 insertions(+), 27 deletions(-)

src/ir.cpp+53-26
......@@ -20575,6 +20575,44 @@ static ZigType *adjust_ptr_allow_zero(CodeGen *g, ZigType *ptr_type, bool allow_
2057520575 allow_zero);
2057620576}
2057720577
20578static Error compute_elem_align(IrAnalyze *ira, ZigType *elem_type, uint32_t base_ptr_align,
20579 uint64_t elem_index, uint32_t *result)
20580{
20581 Error err;
20582
20583 if (base_ptr_align == 0) {
20584 *result = 0;
20585 return ErrorNone;
20586 }
20587
20588 // figure out the largest alignment possible
20589 if ((err = type_resolve(ira->codegen, elem_type, ResolveStatusSizeKnown)))
20590 return err;
20591
20592 uint64_t elem_size = type_size(ira->codegen, elem_type);
20593 uint64_t abi_align = get_abi_alignment(ira->codegen, elem_type);
20594 uint64_t ptr_align = base_ptr_align;
20595
20596 uint64_t chosen_align = abi_align;
20597 if (ptr_align >= abi_align) {
20598 while (ptr_align > abi_align) {
20599 if ((elem_index * elem_size) % ptr_align == 0) {
20600 chosen_align = ptr_align;
20601 break;
20602 }
20603 ptr_align >>= 1;
20604 }
20605 } else if (elem_size >= ptr_align && elem_size % ptr_align == 0) {
20606 chosen_align = ptr_align;
20607 } else {
20608 // can't get here because guaranteed elem_size >= abi_align
20609 zig_unreachable();
20610 }
20611
20612 *result = chosen_align;
20613 return ErrorNone;
20614}
20615
2057820616static IrInstGen *ir_analyze_instruction_elem_ptr(IrAnalyze *ira, IrInstSrcElemPtr *elem_ptr_instruction) {
2057920617 Error err;
2058020618 IrInstGen *array_ptr = elem_ptr_instruction->array_ptr->child;
......@@ -20713,29 +20751,11 @@ static IrInstGen *ir_analyze_instruction_elem_ptr(IrAnalyze *ira, IrInstSrcElemP
2071320751 get_ptr_align(ira->codegen, ptr_type), 0, host_vec_len, false, (uint32_t)index,
2071420752 nullptr, nullptr);
2071520753 } else if (return_type->data.pointer.explicit_alignment != 0) {
20716 // figure out the largest alignment possible
20717
20718 if ((err = type_resolve(ira->codegen, return_type->data.pointer.child_type, ResolveStatusSizeKnown)))
20754 uint32_t chosen_align;
20755 if ((err = compute_elem_align(ira, return_type->data.pointer.child_type,
20756 return_type->data.pointer.explicit_alignment, index, &chosen_align)))
20757 {
2071920758 return ira->codegen->invalid_inst_gen;
20720
20721 uint64_t elem_size = type_size(ira->codegen, return_type->data.pointer.child_type);
20722 uint64_t abi_align = get_abi_alignment(ira->codegen, return_type->data.pointer.child_type);
20723 uint64_t ptr_align = get_ptr_align(ira->codegen, return_type);
20724
20725 uint64_t chosen_align = abi_align;
20726 if (ptr_align >= abi_align) {
20727 while (ptr_align > abi_align) {
20728 if ((index * elem_size) % ptr_align == 0) {
20729 chosen_align = ptr_align;
20730 break;
20731 }
20732 ptr_align >>= 1;
20733 }
20734 } else if (elem_size >= ptr_align && elem_size % ptr_align == 0) {
20735 chosen_align = ptr_align;
20736 } else {
20737 // can't get here because guaranteed elem_size >= abi_align
20738 zig_unreachable();
2073920759 }
2074020760 return_type = adjust_ptr_align(ira->codegen, return_type, chosen_align);
2074120761 }
......@@ -26172,6 +26192,8 @@ static IrInstGen *ir_analyze_instruction_memcpy(IrAnalyze *ira, IrInstSrcMemcpy
2617226192}
2617326193
2617426194static IrInstGen *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstSrcSlice *instruction) {
26195 Error err;
26196
2617526197 IrInstGen *ptr_ptr = instruction->ptr->child;
2617626198 if (type_is_invalid(ptr_ptr->value->type))
2617726199 return ira->codegen->invalid_inst_gen;
......@@ -26307,10 +26329,13 @@ static IrInstGen *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstSrcSlice *i
2630726329 return ira->codegen->invalid_inst_gen;
2630826330 }
2630926331
26310 // TODO in the case of non-zero start index, the byte alignment should be smarter here.
26311 // we should be able to use the same logic as indexing.
26312 uint32_t ptr_byte_alignment = ((end_scalar - start_scalar != 0) && start_scalar == 0) ?
26313 non_sentinel_slice_ptr_type->data.pointer.explicit_alignment : 0;
26332 uint32_t base_ptr_align = non_sentinel_slice_ptr_type->data.pointer.explicit_alignment;
26333 uint32_t ptr_byte_alignment = 0;
26334 if (end_scalar > start_scalar) {
26335 if ((err = compute_elem_align(ira, elem_type, base_ptr_align, start_scalar, &ptr_byte_alignment)))
26336 return ira->codegen->invalid_inst_gen;
26337 }
26338
2631426339 ZigType *return_array_type = get_array_type(ira->codegen, elem_type, end_scalar - start_scalar,
2631526340 array_sentinel);
2631626341 return_type = get_pointer_to_type_extra(ira->codegen, return_array_type,
......@@ -26318,9 +26343,11 @@ static IrInstGen *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstSrcSlice *i
2631826343 non_sentinel_slice_ptr_type->data.pointer.is_volatile,
2631926344 PtrLenSingle, ptr_byte_alignment, 0, 0, false);
2632026345 } else if (sentinel_val != nullptr) {
26346 // TODO deal with non-abi-alignment here
2632126347 ZigType *slice_ptr_type = adjust_ptr_sentinel(ira->codegen, non_sentinel_slice_ptr_type, sentinel_val);
2632226348 return_type = get_slice_type(ira->codegen, slice_ptr_type);
2632326349 } else {
26350 // TODO deal with non-abi-alignment here
2632426351 return_type = get_slice_type(ira->codegen, non_sentinel_slice_ptr_type);
2632526352 }
2632626353
test/stage1/behavior/slice.zig+1-1
......@@ -10,7 +10,7 @@ test "compile time slice of pointer to hard coded address" {
1010 expect(@ptrToInt(x) == 0x1000);
1111 expect(x.len == 0x500);
1212
13 expect(@ptrToInt(y.ptr) == 0x1100);
13 expect(@ptrToInt(y) == 0x1100);
1414 expect(y.len == 0x400);
1515}
1616