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wasm: saturating shift-left for signed integers

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This commit is contained in:
Luuk de Gram 2022-06-19 15:50:03 +02:00
parent 53831442ef
commit 05600a6d84
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GPG Key ID: A8CFE58E4DC7D664
1 changed files with 55 additions and 10 deletions
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65
src/arch/wasm/CodeGen.zig
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@ -4995,13 +4995,13 @@ fn airShlSat(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const bin_op = self.air.instructions.items(.data)[inst].bin_op;
const ty = self.air.typeOfIndex(inst);
const int_info = ty.intInfo(self.target);
const is_signed = int_info.signedness == .signed;
if (int_info.bits > 64) {
return self.fail("TODO: Saturating shifting left for integers with bitsize '{d}'", .{int_info.bits});
}
const lhs = try self.resolveInst(bin_op.lhs);
const rhs = try self.resolveInst(bin_op.rhs);
if (int_info.signedness == .signed) {}
const wasm_bits = toWasmBits(int_info.bits).?;
const result = try self.allocLocal(ty);
@ -5009,10 +5009,32 @@ fn airShlSat(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const shl = try self.binOp(lhs, rhs, ty, .shl);
const shr = try self.binOp(shl, rhs, ty, .shr);
const cmp_result = try self.cmp(lhs, shr, ty, .neq);
if (wasm_bits == 32)
try self.addImm32(-1)
else
try self.addImm64(@bitCast(u64, @as(i64, -1)));
switch (wasm_bits) {
32 => blk: {
if (!is_signed) {
try self.addImm32(-1);
break :blk;
}
const less_than_zero = try self.cmp(lhs, .{ .imm32 = 0 }, ty, .lt);
try self.addImm32(std.math.minInt(i32));
try self.addImm32(std.math.maxInt(i32));
try self.emitWValue(less_than_zero);
try self.addTag(.select);
},
64 => blk: {
if (!is_signed) {
try self.addImm64(@bitCast(u64, @as(i64, -1)));
break :blk;
}
const less_than_zero = try self.cmp(lhs, .{ .imm64 = 0 }, ty, .lt);
try self.addImm64(@bitCast(u64, @as(i64, std.math.minInt(i64))));
try self.addImm64(@bitCast(u64, @as(i64, std.math.maxInt(i64))));
try self.emitWValue(less_than_zero);
try self.addTag(.select);
},
else => unreachable,
}
try self.emitWValue(shl);
try self.emitWValue(cmp_result);
try self.addTag(.select);
@ -5029,12 +5051,35 @@ fn airShlSat(self: *Self, inst: Air.Inst.Index) InnerError!WValue {
const shl_res = try self.binOp(lhs, shift_value, ty, .shl);
const shl = try self.binOp(shl_res, rhs, ty, .shl);
const shr = try self.binOp(shl, rhs, ty, .shr);
const cmp_result = try self.cmp(shl_res, shr, ty, .neq);
if (wasm_bits == 32)
try self.addImm32(-1)
else
try self.addImm64(@bitCast(u64, @as(i64, -1)));
switch (wasm_bits) {
32 => blk: {
if (!is_signed) {
try self.addImm32(-1);
break :blk;
}
const less_than_zero = try self.cmp(shl_res, .{ .imm32 = 0 }, ty, .lt);
try self.addImm32(std.math.minInt(i32));
try self.addImm32(std.math.maxInt(i32));
try self.emitWValue(less_than_zero);
try self.addTag(.select);
},
64 => blk: {
if (!is_signed) {
try self.addImm64(@bitCast(u64, @as(i64, -1)));
break :blk;
}
const less_than_zero = try self.cmp(shl_res, .{ .imm64 = 0 }, ty, .lt);
try self.addImm64(@bitCast(u64, @as(i64, std.math.minInt(i64))));
try self.addImm64(@bitCast(u64, @as(i64, std.math.maxInt(i64))));
try self.emitWValue(less_than_zero);
try self.addTag(.select);
},
else => unreachable,
}
try self.emitWValue(shl);
try self.emitWValue(cmp_result);
try self.addTag(.select);