stage2-wasm: fix div and rem

1 files changed, 43 insertions, 2 deletions

diff --git a/src/arch/wasm/CodeGen.zig b/src/arch/wasm/CodeGen.zig
index d4cba71bf6..b33f5052e7 100644
--- a/src/arch/wasm/CodeGen.zig
+++ b/src/arch/wasm/CodeGen.zig
@@ -1841,7 +1841,7 @@ fn genInst(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
         .bit_or => func.airBinOp(inst, .@"or"),
         .bool_and => func.airBinOp(inst, .@"and"),
         .bool_or => func.airBinOp(inst, .@"or"),
-        .rem => func.airBinOp(inst, .rem),
+        .rem => func.airRem(inst),
         .mod => func.airMod(inst),
         .shl => func.airWrapBinOp(inst, .shl),
         .shl_exact => func.airBinOp(inst, .shl),
@@ -6917,13 +6917,54 @@ fn divSigned(func: *CodeGen, lhs: WValue, rhs: WValue, ty: Type) InnerError!WVal
         try func.emitWValue(lhs);
         try func.emitWValue(rhs);
     }
-    try func.addTag(.i32_div_s);
+    switch (wasm_bits) {
+        32 => try func.addTag(.i32_div_s),
+        64 => try func.addTag(.i64_div_s),
+        else => unreachable,
+    }
+    _ = try func.wrapOperand(.stack, ty);
 
     const result = try func.allocLocal(ty);
     try func.addLabel(.local_set, result.local.value);
     return result;
 }
 
+fn airRem(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
+    const bin_op = func.air.instructions.items(.data)[@intFromEnum(inst)].bin_op;
+
+    const mod = func.bin_file.base.comp.module.?;
+    const ty = func.typeOfIndex(inst);
+    const lhs = try func.resolveInst(bin_op.lhs);
+    const rhs = try func.resolveInst(bin_op.rhs);
+
+    const result = if (ty.isSignedInt(mod)) result: {
+        const int_bits = ty.intInfo(mod).bits;
+        const wasm_bits = toWasmBits(int_bits) orelse {
+            return func.fail("TODO: `@rem` for signed integers larger than 128 bits ({d} bits requested)", .{int_bits});
+        };
+
+        if (wasm_bits > 64) {
+            return func.fail("TODO: `@rem` for signed integers larger than 64 bits ({d} bits requested)", .{int_bits});
+        }
+
+        const lhs_wasm = if (wasm_bits != int_bits)
+            try (try func.signExtendInt(lhs, ty)).toLocal(func, ty)
+        else
+            lhs;
+
+        const rhs_wasm = if (wasm_bits != int_bits)
+            try (try func.signExtendInt(rhs, ty)).toLocal(func, ty)
+        else
+            rhs;
+
+        _ = try func.binOp(lhs_wasm, rhs_wasm, ty, .rem);
+        break :result try func.wrapOperand(.stack, ty);
+    } else try func.binOp(lhs, rhs, ty, .rem);
+
+    const return_local = try result.toLocal(func, ty);
+    func.finishAir(inst, return_local, &.{ bin_op.lhs, bin_op.rhs });
+}
+
 /// Remainder after floor division, defined by:
 /// @divFloor(a, b) * b + @mod(a, b) = a
 fn airMod(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {