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wasm: Implement @maximum & @minimum

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This implements the `max` and `min` AIR instructions by checking
whether LHS is great/lesser than RHS. If that's the case, we assign
LHS to the result, otherwise assign RHS to it instead.
This commit is contained in:
Luuk de Gram 2022-04-02 15:48:26 +02:00
parent 3ee44ce949
commit 219fa192c6
1 changed files with 41 additions and 2 deletions
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43
src/arch/wasm/CodeGen.zig
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@ -1307,6 +1307,8 @@ fn genInst(self: *Self, inst: Air.Inst.Index) !WValue {
.shl_exact => self.airBinOp(inst, .shl),
.shr, .shr_exact => self.airBinOp(inst, .shr),
.xor => self.airBinOp(inst, .xor),
.max => self.airMaxMin(inst, .max),
.min => self.airMaxMin(inst, .min),
.add_with_overflow => self.airBinOpOverflow(inst, .add),
.sub_with_overflow => self.airBinOpOverflow(inst, .sub),
@ -1431,8 +1433,6 @@ fn genInst(self: *Self, inst: Air.Inst.Index) !WValue {
.div_floor,
.div_exact,
.mod,
.max,
.min,
.assembly,
.shl_sat,
.ret_addr,
@ -3873,3 +3873,42 @@ fn airBinOpOverflow(self: *Self, inst: Air.Inst.Index, op: Op) InnerError!WValue
return result_ptr;
}
fn airMaxMin(self: *Self, inst: Air.Inst.Index, op: enum { max, min }) InnerError!WValue {
if (self.liveness.isUnused(inst)) return WValue{ .none = {} };
const bin_op = self.air.instructions.items(.data)[inst].bin_op;
const ty = self.air.typeOfIndex(inst);
if (ty.zigTypeTag() == .Vector) {
return self.fail("TODO: `@maximum` and `@minimum` for vectors", .{});
}
if (ty.abiSize(self.target) > 8) {
return self.fail("TODO: `@maximum` and `@minimum` for types larger than 8 bytes", .{});
}
const lhs = try self.resolveInst(bin_op.lhs);
const rhs = try self.resolveInst(bin_op.rhs);
const result = try self.allocLocal(ty);
try self.startBlock(.block, wasm.block_empty);
try self.startBlock(.block, wasm.block_empty);
// check if LHS is greater/lesser than RHS
const cmp_result = try self.cmp(lhs, rhs, ty, if (op == .max) .gt else .lt);
try self.addLabel(.local_get, cmp_result.local);
try self.addLabel(.br_if, 0); // break to outer loop if LHS is greater/lesser than RHS
// set RHS as max/min
try self.emitWValue(rhs);
try self.addLabel(.local_set, result.local);
try self.addLabel(.br, 1); // break out of all blocks
try self.endBlock();
// set LHS as max/min
try self.emitWValue(lhs);
try self.addLabel(.local_set, result.local);
try self.endBlock();
return result;
}