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Merge pull request #5797 from xackus/intcast-runtime-safety

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stage1: `@intcast` runtime safety for unsigned -> signed of same bit count
This commit is contained in:
Andrew Kelley 2020-07-05 22:24:25 +00:00 committed by GitHub
commit dcca5cf1a9
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5 changed files with 19 additions and 7 deletions
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2
lib/std/special/compiler_rt/clzsi2_test.zig
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@ -4,7 +4,7 @@ const testing = @import("std").testing;
fn test__clzsi2(a: u32, expected: i32) void {
var nakedClzsi2 = clzsi2.__clzsi2;
var actualClzsi2 = @ptrCast(fn (a: i32) callconv(.C) i32, nakedClzsi2);
var x = @intCast(i32, a);
var x = @bitCast(i32, a);
var result = actualClzsi2(x);
testing.expectEqual(expected, result);
}

2
lib/std/special/compiler_rt/int.zig
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@ -244,7 +244,7 @@ pub fn __udivsi3(n: u32, d: u32) callconv(.C) u32 {
// r.all -= d.all;
// carry = 1;
// }
const s = @intCast(i32, d -% r -% 1) >> @intCast(u5, n_uword_bits - 1);
const s = @bitCast(i32, d -% r -% 1) >> @intCast(u5, n_uword_bits - 1);
carry = @intCast(u32, s & 1);
r -= d & @bitCast(u32, s);
}

2
lib/std/special/compiler_rt/udivmod.zig
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@ -184,7 +184,7 @@ pub fn udivmod(comptime DoubleInt: type, a: DoubleInt, b: DoubleInt, maybe_rem:
// carry = 1;
// }
r_all = @ptrCast(*align(@alignOf(SingleInt)) DoubleInt, &r[0]).*; // TODO issue #421
const s: SignedDoubleInt = @intCast(SignedDoubleInt, b -% r_all -% 1) >> (DoubleInt.bit_count - 1);
const s: SignedDoubleInt = @bitCast(SignedDoubleInt, b -% r_all -% 1) >> (DoubleInt.bit_count - 1);
carry = @intCast(u32, s & 1);
r_all -= b & @bitCast(DoubleInt, s);
r = @ptrCast(*[2]SingleInt, &r_all).*; // TODO issue #421

10
src/codegen.cpp
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@ -1535,9 +1535,11 @@ static LLVMValueRef gen_widen_or_shorten(CodeGen *g, bool want_runtime_safety, Z
zig_unreachable();
}
if (actual_type->id == ZigTypeIdInt &&
!wanted_type->data.integral.is_signed && actual_type->data.integral.is_signed &&
want_runtime_safety)
if (actual_type->id == ZigTypeIdInt && want_runtime_safety && (
// negative to unsigned
(!wanted_type->data.integral.is_signed && actual_type->data.integral.is_signed) ||
// unsigned would become negative
(wanted_type->data.integral.is_signed && !actual_type->data.integral.is_signed && actual_bits == wanted_bits)))
{
LLVMValueRef zero = LLVMConstNull(get_llvm_type(g, actual_type));
LLVMValueRef ok_bit = LLVMBuildICmp(g->builder, LLVMIntSGE, expr_val, zero, "");
@ -1547,7 +1549,7 @@ static LLVMValueRef gen_widen_or_shorten(CodeGen *g, bool want_runtime_safety, Z
LLVMBuildCondBr(g->builder, ok_bit, ok_block, fail_block);
LLVMPositionBuilderAtEnd(g->builder, fail_block);
gen_safety_crash(g, PanicMsgIdCastNegativeToUnsigned);
gen_safety_crash(g, actual_type->data.integral.is_signed ? PanicMsgIdCastNegativeToUnsigned : PanicMsgIdCastTruncatedData);
LLVMPositionBuilderAtEnd(g->builder, ok_block);
}

10
test/runtime_safety.zig
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@ -757,6 +757,16 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
\\}
);
cases.addRuntimeSafety("unsigned integer not fitting in cast to signed integer - same bit count",
\\pub fn panic(message: []const u8, stack_trace: ?*@import("builtin").StackTrace) noreturn {
\\ @import("std").os.exit(126);
\\}
\\pub fn main() void {
\\ var value: u8 = 245;
\\ var casted = @intCast(i8, value);
\\}
);
cases.addRuntimeSafety("unwrap error",
\\pub fn panic(message: []const u8, stack_trace: ?*@import("builtin").StackTrace) noreturn {
\\ if (@import("std").mem.eql(u8, message, "attempt to unwrap error: Whatever")) {