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spirv: vectorize add/sub overflow

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Robin Voetter 2024-01-19 23:56:02 +01:00
parent 761594e226
commit b67d983abd
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2 changed files with 84 additions and 81 deletions
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161
src/codegen/spirv.zig
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@ -2582,103 +2582,108 @@ const DeclGen = struct {
const lhs = try self.resolve(extra.lhs);
const rhs = try self.resolve(extra.rhs);
const operand_ty = self.typeOf(extra.lhs);
const result_ty = self.typeOfIndex(inst);
const operand_ty = self.typeOf(extra.lhs);
const ov_ty = result_ty.structFieldType(1, self.module);
const bool_ty_ref = try self.resolveType(Type.bool, .direct);
const info = try self.arithmeticTypeInfo(operand_ty);
switch (info.class) {
.composite_integer => return self.todo("overflow ops for composite integers", .{}),
.strange_integer => return self.todo("overflow ops for strange integers", .{}),
.integer => {},
.strange_integer, .integer => {},
.float, .bool => unreachable,
}
// The operand type must be the same as the result type in SPIR-V, which
// is the same as in Zig.
const operand_ty_ref = try self.resolveType(operand_ty, .direct);
const operand_ty_id = self.typeId(operand_ty_ref);
var wip_result = try self.elementWise(operand_ty);
defer wip_result.deinit();
var wip_ov = try self.elementWise(ov_ty);
defer wip_ov.deinit();
for (wip_result.results, wip_ov.results, 0..) |*value_id, *ov_id, i| {
const lhs_elem_id = try wip_result.elementAt(operand_ty, lhs, i);
const rhs_elem_id = try wip_result.elementAt(operand_ty, rhs, i);
const bool_ty_ref = try self.resolveType(Type.bool, .direct);
// Normalize both so that we can properly check for overflow
const lhs_norm_id = try self.normalizeInt(wip_result.scalar_ty_ref, lhs_elem_id, info);
const rhs_norm_id = try self.normalizeInt(wip_result.scalar_ty_ref, rhs_elem_id, info);
const op_result_id = self.spv.allocId();
const ov_ty = result_ty.structFieldType(1, self.module);
// Note: result is stored in a struct, so indirect representation.
const ov_ty_ref = try self.resolveType(ov_ty, .indirect);
try self.func.body.emit(self.spv.gpa, add, .{
.id_result_type = wip_result.scalar_ty_id,
.id_result = op_result_id,
.operand_1 = lhs_norm_id,
.operand_2 = rhs_norm_id,
});
// TODO: Operations other than addition.
const value_id = self.spv.allocId();
try self.func.body.emit(self.spv.gpa, add, .{
.id_result_type = operand_ty_id,
.id_result = value_id,
.operand_1 = lhs,
.operand_2 = rhs,
});
// Normalize the result so that the comparisons go well
value_id.* = try self.normalizeInt(wip_result.scalar_ty_ref, op_result_id, info);
const overflowed_id = switch (info.signedness) {
.unsigned => blk: {
// Overflow happened if the result is smaller than either of the operands. It doesn't matter which.
// For subtraction the conditions need to be swapped.
const overflowed_id = self.spv.allocId();
try self.func.body.emit(self.spv.gpa, ucmp, .{
.id_result_type = self.typeId(bool_ty_ref),
.id_result = overflowed_id,
.operand_1 = value_id,
.operand_2 = lhs,
});
break :blk overflowed_id;
},
.signed => blk: {
// lhs - rhs
// For addition, overflow happened if:
// - rhs is negative and value > lhs
// - rhs is positive and value < lhs
// This can be shortened to:
// (rhs < 0 and value > lhs) or (rhs >= 0 and value <= lhs)
// = (rhs < 0) == (value > lhs)
// = (rhs < 0) == (lhs < value)
// Note that signed overflow is also wrapping in spir-v.
// For subtraction, overflow happened if:
// - rhs is negative and value < lhs
// - rhs is positive and value > lhs
// This can be shortened to:
// (rhs < 0 and value < lhs) or (rhs >= 0 and value >= lhs)
// = (rhs < 0) == (value < lhs)
// = (rhs < 0) == (lhs > value)
const overflowed_id = switch (info.signedness) {
.unsigned => blk: {
// Overflow happened if the result is smaller than either of the operands. It doesn't matter which.
// For subtraction the conditions need to be swapped.
const overflowed_id = self.spv.allocId();
try self.func.body.emit(self.spv.gpa, ucmp, .{
.id_result_type = self.typeId(bool_ty_ref),
.id_result = overflowed_id,
.operand_1 = value_id.*,
.operand_2 = lhs_norm_id,
});
break :blk overflowed_id;
},
.signed => blk: {
// lhs - rhs
// For addition, overflow happened if:
// - rhs is negative and value > lhs
// - rhs is positive and value < lhs
// This can be shortened to:
// (rhs < 0 and value > lhs) or (rhs >= 0 and value <= lhs)
// = (rhs < 0) == (value > lhs)
// = (rhs < 0) == (lhs < value)
// Note that signed overflow is also wrapping in spir-v.
// For subtraction, overflow happened if:
// - rhs is negative and value < lhs
// - rhs is positive and value > lhs
// This can be shortened to:
// (rhs < 0 and value < lhs) or (rhs >= 0 and value >= lhs)
// = (rhs < 0) == (value < lhs)
// = (rhs < 0) == (lhs > value)
const rhs_lt_zero_id = self.spv.allocId();
const zero_id = try self.constInt(operand_ty_ref, 0);
try self.func.body.emit(self.spv.gpa, .OpSLessThan, .{
.id_result_type = self.typeId(bool_ty_ref),
.id_result = rhs_lt_zero_id,
.operand_1 = rhs,
.operand_2 = zero_id,
});
const rhs_lt_zero_id = self.spv.allocId();
const zero_id = try self.constInt(wip_result.scalar_ty_ref, 0);
try self.func.body.emit(self.spv.gpa, .OpSLessThan, .{
.id_result_type = self.typeId(bool_ty_ref),
.id_result = rhs_lt_zero_id,
.operand_1 = rhs_norm_id,
.operand_2 = zero_id,
});
const value_gt_lhs_id = self.spv.allocId();
try self.func.body.emit(self.spv.gpa, scmp, .{
.id_result_type = self.typeId(bool_ty_ref),
.id_result = value_gt_lhs_id,
.operand_1 = lhs,
.operand_2 = value_id,
});
const value_gt_lhs_id = self.spv.allocId();
try self.func.body.emit(self.spv.gpa, scmp, .{
.id_result_type = self.typeId(bool_ty_ref),
.id_result = value_gt_lhs_id,
.operand_1 = lhs_norm_id,
.operand_2 = value_id.*,
});
const overflowed_id = self.spv.allocId();
try self.func.body.emit(self.spv.gpa, .OpLogicalEqual, .{
.id_result_type = self.typeId(bool_ty_ref),
.id_result = overflowed_id,
.operand_1 = rhs_lt_zero_id,
.operand_2 = value_gt_lhs_id,
});
break :blk overflowed_id;
},
};
const overflowed_id = self.spv.allocId();
try self.func.body.emit(self.spv.gpa, .OpLogicalEqual, .{
.id_result_type = self.typeId(bool_ty_ref),
.id_result = overflowed_id,
.operand_1 = rhs_lt_zero_id,
.operand_2 = value_gt_lhs_id,
});
break :blk overflowed_id;
},
};
ov_id.* = try self.intFromBool(wip_ov.scalar_ty_ref, overflowed_id);
}
// Construct the struct that Zig wants as result.
// The value should already be the correct type.
const ov_id = try self.intFromBool(ov_ty_ref, overflowed_id);
return try self.constructStruct(
result_ty,
&.{ operand_ty, ov_ty },
&.{ value_id, ov_id },
&.{ try wip_result.finalize(), try wip_ov.finalize() },
);
}

4
test/behavior/vector.zig
View File

@ -259,7 +259,6 @@ test "tuple to vector" {
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
if (builtin.zig_backend == .stage2_llvm and builtin.cpu.arch == .aarch64) {
// Regressed with LLVM 14:
@ -1063,7 +1062,7 @@ test "@addWithOverflow" {
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
// if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
const S = struct {
fn doTheTest() !void {
@ -1111,7 +1110,6 @@ test "@subWithOverflow" {
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
const S = struct {
fn doTheTest() !void {