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@bitreverse intrinsic, part of #767 (#1865) 

* bitreverse - give bswap behavior

* bitreverse, comptime_ints, negative values still not working?

* bitreverse working for negative comptime ints

* Finished bitreverse test cases

* Undo exporting a bigint function. @bitreverse test name includes ampersand

* added docs entry for @bitreverse
master
vegecode 2019-01-02 15:47:47 -06:00 committed by Andrew Kelley
parent 6df8e4bca7
commit f6cd68386d
9 changed files with 240 additions and 1 deletions
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12
doc/langref.html.in
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@ -5316,6 +5316,18 @@ comptime {
</p>
{#header_close#}
{#header_open|@bitreverse#}
<pre>{#syntax#}@bitreverse(comptime T: type, value: T) T{#endsyntax#}</pre>
<p>{#syntax#}T{#endsyntax#} accepts any integer type.</p>
<p>
Reverses the bitpattern of an integer value, including the sign bit if applicable.
</p>
<p>
For example 0b10110110 ({#syntax#}u8 = 182{#endsyntax#}, {#syntax#}i8 = -74{#endsyntax#})
becomes 0b01101101 ({#syntax#}u8 = 109{#endsyntax#}, {#syntax#}i8 = 109{#endsyntax#}).
</p>
{#header_close#}
{#header_open|@byteOffsetOf#}
<pre>{#syntax#}@byteOffsetOf(comptime T: type, comptime field_name: [] const u8) comptime_int{#endsyntax#}</pre>
<p>

13
src/all_types.hpp
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@ -1415,6 +1415,7 @@ enum BuiltinFnId {
BuiltinFnIdAtomicRmw,
BuiltinFnIdAtomicLoad,
BuiltinFnIdBswap,
BuiltinFnIdBitReverse,
};
struct BuiltinFnEntry {
@ -1488,6 +1489,7 @@ enum ZigLLVMFnId {
ZigLLVMFnIdCeil,
ZigLLVMFnIdSqrt,
ZigLLVMFnIdBswap,
ZigLLVMFnIdBitReverse,
};
enum AddSubMul {
@ -1520,6 +1522,9 @@ struct ZigLLVMFnKey {
struct {
uint32_t bit_count;
} bswap;
struct {
uint32_t bit_count;
} bit_reverse;
} data;
};
@ -2162,6 +2167,7 @@ enum IrInstructionId {
IrInstructionIdMarkErrRetTracePtr,
IrInstructionIdSqrt,
IrInstructionIdBswap,
IrInstructionIdBitReverse,
IrInstructionIdErrSetCast,
IrInstructionIdToBytes,
IrInstructionIdFromBytes,
@ -3262,6 +3268,13 @@ struct IrInstructionBswap {
IrInstruction *op;
};
struct IrInstructionBitReverse {
IrInstruction base;
IrInstruction *type;
IrInstruction *op;
};
static const size_t slice_ptr_index = 0;
static const size_t slice_len_index = 1;

4
src/analyze.cpp
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@ -6121,6 +6121,8 @@ uint32_t zig_llvm_fn_key_hash(ZigLLVMFnKey x) {
return (uint32_t)(x.data.floating.bit_count) * (uint32_t)2225366385;
case ZigLLVMFnIdBswap:
return (uint32_t)(x.data.bswap.bit_count) * (uint32_t)3661994335;
case ZigLLVMFnIdBitReverse:
return (uint32_t)(x.data.bit_reverse.bit_count) * (uint32_t)2621398431;
case ZigLLVMFnIdOverflowArithmetic:
return ((uint32_t)(x.data.overflow_arithmetic.bit_count) * 87135777) +
((uint32_t)(x.data.overflow_arithmetic.add_sub_mul) * 31640542) +
@ -6141,6 +6143,8 @@ bool zig_llvm_fn_key_eql(ZigLLVMFnKey a, ZigLLVMFnKey b) {
return a.data.pop_count.bit_count == b.data.pop_count.bit_count;
case ZigLLVMFnIdBswap:
return a.data.bswap.bit_count == b.data.bswap.bit_count;
case ZigLLVMFnIdBitReverse:
return a.data.bit_reverse.bit_count == b.data.bit_reverse.bit_count;
case ZigLLVMFnIdFloor:
case ZigLLVMFnIdCeil:
case ZigLLVMFnIdSqrt:

1
src/bigint.cpp
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@ -1722,3 +1722,4 @@ void bigint_incr(BigInt *x) {
bigint_add(x, &copy, &one);
}

16
src/codegen.cpp
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@ -3789,6 +3789,11 @@ static LLVMValueRef get_int_builtin_fn(CodeGen *g, ZigType *int_type, BuiltinFnI
n_args = 1;
key.id = ZigLLVMFnIdBswap;
key.data.bswap.bit_count = (uint32_t)int_type->data.integral.bit_count;
} else if (fn_id == BuiltinFnIdBitReverse) {
fn_name = "bitreverse";
n_args = 1;
key.id = ZigLLVMFnIdBitReverse;
key.data.bit_reverse.bit_count = (uint32_t)int_type->data.integral.bit_count;
} else {
zig_unreachable();
}
@ -5096,6 +5101,14 @@ static LLVMValueRef ir_render_bswap(CodeGen *g, IrExecutable *executable, IrInst
return LLVMBuildTrunc(g->builder, shifted, int_type->type_ref, "");
}
static LLVMValueRef ir_render_bit_reverse(CodeGen *g, IrExecutable *executable, IrInstructionBitReverse *instruction) {
LLVMValueRef op = ir_llvm_value(g, instruction->op);
ZigType *int_type = instruction->base.value.type;
assert(int_type->id == ZigTypeIdInt);
LLVMValueRef fn_val = get_int_builtin_fn(g, instruction->base.value.type, BuiltinFnIdBitReverse);
return LLVMBuildCall(g->builder, fn_val, &op, 1, "");
}
static void set_debug_location(CodeGen *g, IrInstruction *instruction) {
AstNode *source_node = instruction->source_node;
Scope *scope = instruction->scope;
@ -5335,6 +5348,8 @@ static LLVMValueRef ir_render_instruction(CodeGen *g, IrExecutable *executable,
return ir_render_sqrt(g, executable, (IrInstructionSqrt *)instruction);
case IrInstructionIdBswap:
return ir_render_bswap(g, executable, (IrInstructionBswap *)instruction);
case IrInstructionIdBitReverse:
return ir_render_bit_reverse(g, executable, (IrInstructionBitReverse *)instruction);
}
zig_unreachable();
}
@ -6758,6 +6773,7 @@ static void define_builtin_fns(CodeGen *g) {
create_builtin_fn(g, BuiltinFnIdFromBytes, "bytesToSlice", 2);
create_builtin_fn(g, BuiltinFnIdThis, "This", 0);
create_builtin_fn(g, BuiltinFnIdBswap, "bswap", 2);
create_builtin_fn(g, BuiltinFnIdBitReverse, "bitreverse", 2);
}
static const char *bool_to_str(bool b) {

98
src/ir.cpp
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@ -861,6 +861,10 @@ static constexpr IrInstructionId ir_instruction_id(IrInstructionBswap *) {
return IrInstructionIdBswap;
}
static constexpr IrInstructionId ir_instruction_id(IrInstructionBitReverse *) {
return IrInstructionIdBitReverse;
}
static constexpr IrInstructionId ir_instruction_id(IrInstructionCheckRuntimeScope *) {
return IrInstructionIdCheckRuntimeScope;
}
@ -2721,6 +2725,17 @@ static IrInstruction *ir_build_bswap(IrBuilder *irb, Scope *scope, AstNode *sour
return &instruction->base;
}
static IrInstruction *ir_build_bit_reverse(IrBuilder *irb, Scope *scope, AstNode *source_node, IrInstruction *type, IrInstruction *op) {
IrInstructionBitReverse *instruction = ir_build_instruction<IrInstructionBitReverse>(irb, scope, source_node);
instruction->type = type;
instruction->op = op;
if (type != nullptr) ir_ref_instruction(type, irb->current_basic_block);
ir_ref_instruction(op, irb->current_basic_block);
return &instruction->base;
}
static IrInstruction *ir_build_check_runtime_scope(IrBuilder *irb, Scope *scope, AstNode *source_node, IrInstruction *scope_is_comptime, IrInstruction *is_comptime) {
IrInstructionCheckRuntimeScope *instruction = ir_build_instruction<IrInstructionCheckRuntimeScope>(irb, scope, source_node);
instruction->scope_is_comptime = scope_is_comptime;
@ -3646,7 +3661,7 @@ static IrInstruction *ir_gen_builtin_fn_call(IrBuilder *irb, Scope *scope, AstNo
Buf *name = fn_ref_expr->data.symbol_expr.symbol;
auto entry = irb->codegen->builtin_fn_table.maybe_get(name);
if (!entry) {
if (!entry) { // new built in not found
add_node_error(irb->codegen, node,
buf_sprintf("invalid builtin function: '%s'", buf_ptr(name)));
return irb->codegen->invalid_instruction;
@ -4720,6 +4735,21 @@ static IrInstruction *ir_gen_builtin_fn_call(IrBuilder *irb, Scope *scope, AstNo
IrInstruction *result = ir_build_bswap(irb, scope, node, arg0_value, arg1_value);
return ir_lval_wrap(irb, scope, result, lval);
}
case BuiltinFnIdBitReverse:
{
AstNode *arg0_node = node->data.fn_call_expr.params.at(0);
IrInstruction *arg0_value = ir_gen_node(irb, arg0_node, scope);
if (arg0_value == irb->codegen->invalid_instruction)
return arg0_value;
AstNode *arg1_node = node->data.fn_call_expr.params.at(1);
IrInstruction *arg1_value = ir_gen_node(irb, arg1_node, scope);
if (arg1_value == irb->codegen->invalid_instruction)
return arg1_value;
IrInstruction *result = ir_build_bit_reverse(irb, scope, node, arg0_value, arg1_value);
return ir_lval_wrap(irb, scope, result, lval);
}
}
zig_unreachable();
}
@ -21115,6 +21145,69 @@ static IrInstruction *ir_analyze_instruction_bswap(IrAnalyze *ira, IrInstruction
return result;
}
static IrInstruction *ir_analyze_instruction_bit_reverse(IrAnalyze *ira, IrInstructionBitReverse *instruction) {
ZigType *int_type = ir_resolve_type(ira, instruction->type->child);
if (type_is_invalid(int_type))
return ira->codegen->invalid_instruction;
IrInstruction *op = instruction->op->child;
if (type_is_invalid(op->value.type))
return ira->codegen->invalid_instruction;
if (int_type->id != ZigTypeIdInt) {
ir_add_error(ira, instruction->type,
buf_sprintf("expected integer type, found '%s'", buf_ptr(&int_type->name)));
return ira->codegen->invalid_instruction;
}
IrInstruction *casted_op = ir_implicit_cast(ira, op, int_type);
if (type_is_invalid(casted_op->value.type))
return ira->codegen->invalid_instruction;
if (int_type->data.integral.bit_count == 0) {
IrInstruction *result = ir_const(ira, &instruction->base, int_type);
bigint_init_unsigned(&result->value.data.x_bigint, 0);
return result;
}
if (instr_is_comptime(casted_op)) {
ConstExprValue *val = ir_resolve_const(ira, casted_op, UndefBad);
if (!val)
return ira->codegen->invalid_instruction;
IrInstruction *result = ir_const(ira, &instruction->base, int_type);
size_t num_bits = int_type->data.integral.bit_count;
size_t buf_size = (num_bits + 7) / 8;
uint8_t *comptime_buf = allocate_nonzero<uint8_t>(buf_size);
uint8_t *result_buf = allocate_nonzero<uint8_t>(buf_size);
memset(comptime_buf,0,buf_size);
memset(result_buf,0,buf_size);
bigint_write_twos_complement(&val->data.x_bigint,comptime_buf,num_bits,ira->codegen->is_big_endian);
size_t bit_i = 0;
size_t bit_rev_i = num_bits - 1;
for (; bit_i < num_bits; bit_i++, bit_rev_i--) {
if (comptime_buf[bit_i / 8] & (1 << (bit_i % 8))) {
result_buf[bit_rev_i / 8] |= (1 << (bit_rev_i % 8));
}
}
bigint_read_twos_complement(&result->value.data.x_bigint,
result_buf,
int_type->data.integral.bit_count,
ira->codegen->is_big_endian,
int_type->data.integral.is_signed);
return result;
}
IrInstruction *result = ir_build_bit_reverse(&ira->new_irb, instruction->base.scope,
instruction->base.source_node, nullptr, casted_op);
result->value.type = int_type;
return result;
}
static IrInstruction *ir_analyze_instruction_enum_to_int(IrAnalyze *ira, IrInstructionEnumToInt *instruction) {
Error err;
@ -21453,6 +21546,8 @@ static IrInstruction *ir_analyze_instruction_nocast(IrAnalyze *ira, IrInstructio
return ir_analyze_instruction_sqrt(ira, (IrInstructionSqrt *)instruction);
case IrInstructionIdBswap:
return ir_analyze_instruction_bswap(ira, (IrInstructionBswap *)instruction);
case IrInstructionIdBitReverse:
return ir_analyze_instruction_bit_reverse(ira, (IrInstructionBitReverse *)instruction);
case IrInstructionIdIntToErr:
return ir_analyze_instruction_int_to_err(ira, (IrInstructionIntToErr *)instruction);
case IrInstructionIdErrToInt:
@ -21675,6 +21770,7 @@ bool ir_has_side_effects(IrInstruction *instruction) {
case IrInstructionIdPromiseResultType:
case IrInstructionIdSqrt:
case IrInstructionIdBswap:
case IrInstructionIdBitReverse:
case IrInstructionIdAtomicLoad:
case IrInstructionIdIntCast:
case IrInstructionIdFloatCast:

15
src/ir_print.cpp
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@ -1335,6 +1335,18 @@ static void ir_print_bswap(IrPrint *irp, IrInstructionBswap *instruction) {
fprintf(irp->f, ")");
}
static void ir_print_bit_reverse(IrPrint *irp, IrInstructionBitReverse *instruction) {
fprintf(irp->f, "@bitreverse(");
if (instruction->type != nullptr) {
ir_print_other_instruction(irp, instruction->type);
} else {
fprintf(irp->f, "null");
}
fprintf(irp->f, ",");
ir_print_other_instruction(irp, instruction->op);
fprintf(irp->f, ")");
}
static void ir_print_instruction(IrPrint *irp, IrInstruction *instruction) {
ir_print_prefix(irp, instruction);
switch (instruction->id) {
@ -1751,6 +1763,9 @@ static void ir_print_instruction(IrPrint *irp, IrInstruction *instruction) {
case IrInstructionIdBswap:
ir_print_bswap(irp, (IrInstructionBswap *)instruction);
break;
case IrInstructionIdBitReverse:
ir_print_bit_reverse(irp, (IrInstructionBitReverse *)instruction);
break;
case IrInstructionIdAtomicLoad:
ir_print_atomic_load(irp, (IrInstructionAtomicLoad *)instruction);
break;

1
test/behavior.zig
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@ -9,6 +9,7 @@ comptime {
_ = @import("cases/bitcast.zig");
_ = @import("cases/bool.zig");
_ = @import("cases/bswap.zig");
_ = @import("cases/bitreverse.zig");
_ = @import("cases/bugs/1076.zig");
_ = @import("cases/bugs/1111.zig");
_ = @import("cases/bugs/1277.zig");

81
test/cases/bitreverse.zig Normal file
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@ -0,0 +1,81 @@
const std = @import("std");
const assert = std.debug.assert;
const minInt = std.math.minInt;
test "@bitreverse" {
comptime testBitReverse();
testBitReverse();
}
fn testBitReverse() void {
// using comptime_ints, unsigned
assert(@bitreverse(u0, 0) == 0);
assert(@bitreverse(u5, 0x12) == 0x9);
assert(@bitreverse(u8, 0x12) == 0x48);
assert(@bitreverse(u16, 0x1234) == 0x2c48);
assert(@bitreverse(u24, 0x123456) == 0x6a2c48);
assert(@bitreverse(u32, 0x12345678) == 0x1e6a2c48);
assert(@bitreverse(u40, 0x123456789a) == 0x591e6a2c48);
assert(@bitreverse(u48, 0x123456789abc) == 0x3d591e6a2c48);
assert(@bitreverse(u56, 0x123456789abcde) == 0x7b3d591e6a2c48);
assert(@bitreverse(u64, 0x123456789abcdef1) == 0x8f7b3d591e6a2c48);
assert(@bitreverse(u128, 0x123456789abcdef11121314151617181) == 0x818e868a828c84888f7b3d591e6a2c48);
// using runtime uints, unsigned
var num0: u0 = 0;
assert(@bitreverse(u0, num0) == 0);
var num5: u5 = 0x12;
assert(@bitreverse(u5, num5) == 0x9);
var num8: u8 = 0x12;
assert(@bitreverse(u8, num8) == 0x48);
var num16: u16 = 0x1234;
assert(@bitreverse(u16, num16) == 0x2c48);
var num24: u24 = 0x123456;
assert(@bitreverse(u24, num24) == 0x6a2c48);
var num32: u32 = 0x12345678;
assert(@bitreverse(u32, num32) == 0x1e6a2c48);
var num40: u40 = 0x123456789a;
assert(@bitreverse(u40, num40) == 0x591e6a2c48);
var num48: u48 = 0x123456789abc;
assert(@bitreverse(u48, num48) == 0x3d591e6a2c48);
var num56: u56 = 0x123456789abcde;
assert(@bitreverse(u56, num56) == 0x7b3d591e6a2c48);
var num64: u64 = 0x123456789abcdef1;
assert(@bitreverse(u64, num64) == 0x8f7b3d591e6a2c48);
var num128: u128 = 0x123456789abcdef11121314151617181;
assert(@bitreverse(u128, num128) == 0x818e868a828c84888f7b3d591e6a2c48);
// using comptime_ints, signed, positive
assert(@bitreverse(i0, 0) == 0);
assert(@bitreverse(i8, @bitCast(i8, u8(0x92))) == @bitCast(i8, u8( 0x49)));
assert(@bitreverse(i16, @bitCast(i16, u16(0x1234))) == @bitCast(i16, u16( 0x2c48)));
assert(@bitreverse(i24, @bitCast(i24, u24(0x123456))) == @bitCast(i24, u24( 0x6a2c48)));
assert(@bitreverse(i32, @bitCast(i32, u32(0x12345678))) == @bitCast(i32, u32( 0x1e6a2c48)));
assert(@bitreverse(i40, @bitCast(i40, u40(0x123456789a))) == @bitCast(i40, u40( 0x591e6a2c48)));
assert(@bitreverse(i48, @bitCast(i48, u48(0x123456789abc))) == @bitCast(i48, u48( 0x3d591e6a2c48)));
assert(@bitreverse(i56, @bitCast(i56, u56(0x123456789abcde))) == @bitCast(i56, u56( 0x7b3d591e6a2c48)));
assert(@bitreverse(i64, @bitCast(i64, u64(0x123456789abcdef1))) == @bitCast(i64,u64(0x8f7b3d591e6a2c48)));
assert(@bitreverse(i128, @bitCast(i128,u128(0x123456789abcdef11121314151617181))) == @bitCast(i128,u128(0x818e868a828c84888f7b3d591e6a2c48)));
// using comptime_ints, signed, negative. Compare to runtime ints returned from llvm.
var neg5: i5 = minInt(i5) + 1;
assert(@bitreverse(i5, minInt(i5) + 1) == @bitreverse(i5, neg5));
var neg8: i8 = -18;
assert(@bitreverse(i8, -18) == @bitreverse(i8, neg8));
var neg16: i16 = -32694;
assert(@bitreverse(i16, -32694) == @bitreverse(i16, neg16));
var neg24: i24 = -6773785;
assert(@bitreverse(i24, -6773785) == @bitreverse(i24, neg24));
var neg32: i32 = -16773785;
assert(@bitreverse(i32, -16773785) == @bitreverse(i32, neg32));
var neg40: i40 = minInt(i40) + 12345;
assert(@bitreverse(i40, minInt(i40) + 12345) == @bitreverse(i40, neg40));
var neg48: i48 = minInt(i48) + 12345;
assert(@bitreverse(i48, minInt(i48) + 12345) == @bitreverse(i48, neg48));
var neg56: i56 = minInt(i56) + 12345;
assert(@bitreverse(i56, minInt(i56) + 12345) == @bitreverse(i56, neg56));
var neg64: i64 = minInt(i64) + 12345;
assert(@bitreverse(i64, minInt(i64) + 12345) == @bitreverse(i64, neg64));
var neg128: i128 = minInt(i128) + 12345;
assert(@bitreverse(i128, minInt(i128) + 12345) == @bitreverse(i128, neg128));
}