zig

commit b3c498454b6006f64aecf96b181720c524d76ae8 (tree)
parent f7f0b9d28f2d68f40fcfe79f85b4cc37ea9ba2e8
Author: Matthew Lugg <mlugg@mlugg.co.uk>
Date:   Fri,  2 Jan 2026 13:37:58 +0000

codegen.wasm: fix 64-bit saturating shl

Previously, 64-bit '<<|' operations were emitting 64-bit shifts with one
64-bit operand and one 32-bit operand, which is illegal. Instead, as in
the lowering for regular shifts, we need to cast the RHS in this case.

Diffstat:
M
src/codegen/wasm/CodeGen.zig
 | 
15
+++++++++++++--

1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/src/codegen/wasm/CodeGen.zig b/src/codegen/wasm/CodeGen.zig
@@ -6973,9 +6973,20 @@ fn airShlSat(cg: *CodeGen, inst: Air.Inst.Index) InnerError!void {
         return cg.fail("TODO: Saturating shifting left for integers with bitsize '{d}'", .{int_info.bits});
     }
 
-    const lhs = try cg.resolveInst(bin_op.lhs);
-    const rhs = try cg.resolveInst(bin_op.rhs);
     const wasm_bits = toWasmBits(int_info.bits).?;
+
+    const lhs = try cg.resolveInst(bin_op.lhs);
+    const rhs = rhs: {
+        const rhs = try cg.resolveInst(bin_op.rhs);
+        const rhs_ty = cg.typeOf(bin_op.rhs);
+        // The type of `rhs` is the log2 int of the type of `lhs`, but WASM wants the lhs and rhs types to match.
+        if (toWasmBits(@intCast(rhs_ty.bitSize(zcu))).? == wasm_bits) {
+            break :rhs rhs; // the WASM types match, so no cast necessary
+        }
+        const casted = try cg.intcast(rhs, rhs_ty, ty);
+        break :rhs try casted.toLocal(cg, ty);
+    };
+
     const result = try cg.allocLocal(ty);
 
     if (wasm_bits == int_info.bits) {