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stage2: fix unsigned integer to signed integer coercion

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This commit is contained in:
Andrew Kelley 2021-09-21 17:24:55 -07:00
parent be71195bba
commit 0e2b9ac777
4 changed files with 20 additions and 12 deletions
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2
src/Sema.zig
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@ -9565,7 +9565,7 @@ fn coerce(
const src_info = inst_ty.intInfo(target);
if ((src_info.signedness == dst_info.signedness and dst_info.bits >= src_info.bits) or
// small enough unsigned ints can get casted to large enough signed ints
(src_info.signedness == .signed and dst_info.signedness == .unsigned and dst_info.bits > src_info.bits))
(dst_info.signedness == .signed and dst_info.bits > src_info.bits))
{
try sema.requireRuntimeBlock(block, inst_src);
return block.addTyOp(.intcast, dest_type, inst);

18
src/codegen/llvm.zig
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@ -2032,14 +2032,22 @@ pub const FuncGen = struct {
if (self.liveness.isUnused(inst))
return null;
const target = self.dg.module.getTarget();
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
const dest_ty = self.air.typeOfIndex(inst);
const dest_info = dest_ty.intInfo(target);
const dest_llvm_ty = try self.dg.llvmType(dest_ty);
const operand = try self.resolveInst(ty_op.operand);
const inst_ty = self.air.typeOfIndex(inst);
const operand_ty = self.air.typeOf(ty_op.operand);
const operand_info = operand_ty.intInfo(target);
const signed = inst_ty.isSignedInt();
// TODO: Should we use intcast here or just a simple bitcast?
// LLVM does truncation vs bitcast (+signed extension) in the intcast depending on the sizes
return self.builder.buildIntCast2(operand, try self.dg.llvmType(inst_ty), llvm.Bool.fromBool(signed), "");
if (operand_info.bits < dest_info.bits) {
switch (operand_info.signedness) {
.signed => return self.builder.buildSExt(operand, dest_llvm_ty, ""),
.unsigned => return self.builder.buildZExt(operand, dest_llvm_ty, ""),
}
}
return self.builder.buildTrunc(operand, dest_llvm_ty, "");
}
fn airTrunc(self: *FuncGen, inst: Air.Inst.Index) !?*const llvm.Value {

6
test/behavior/widening.zig
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@ -11,3 +11,9 @@ test "integer widening" {
var f: u128 = e;
try expect(f == a);
}
test "implicit unsigned integer to signed integer" {
var a: u8 = 250;
var b: i16 = a;
try expect(b == 250);
}

6
test/behavior/widening_stage1.zig
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@ -2,12 +2,6 @@ const std = @import("std");
const expect = std.testing.expect;
const mem = std.mem;
test "implicit unsigned integer to signed integer" {
var a: u8 = 250;
var b: i16 = a;
try expect(b == 250);
}
test "float widening" {
var a: f16 = 12.34;
var b: f32 = a;