Merge pull request #17819 from Luukdegram/wasm-bitcast-fix

wasm - fix bitcasting between arrays and scalar types

Author: andrewrk

lib/test_runner.zig

@@ -13,9 +13,7 @@ var cmdline_buffer: [4096]u8 = undefined;
 var fba = std.heap.FixedBufferAllocator.init(&cmdline_buffer);
 
 pub fn main() void {
-    if (builtin.zig_backend == .stage2_aarch64 or
-        builtin.zig_backend == .stage2_wasm)
-    {
+    if (builtin.zig_backend == .stage2_aarch64) {
         return mainSimple() catch @panic("test failure");
     }
 

src/arch/wasm/CodeGen.zig

@@ -3814,6 +3814,16 @@ fn airBitcast(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
             const bitcast_result = try func.bitcast(wanted_ty, given_ty, operand);
             break :result try bitcast_result.toLocal(func, wanted_ty);
         }
+        const mod = func.bin_file.base.options.module.?;
+        if (isByRef(given_ty, mod) and !isByRef(wanted_ty, mod)) {
+            const loaded_memory = try func.load(operand, wanted_ty, 0);
+            break :result try loaded_memory.toLocal(func, wanted_ty);
+        }
+        if (!isByRef(given_ty, mod) and isByRef(wanted_ty, mod)) {
+            const stack_memory = try func.allocStack(wanted_ty);
+            try func.store(stack_memory, operand, given_ty, 0);
+            break :result stack_memory;
+        }
         break :result func.reuseOperand(ty_op.operand, operand);
     };
     func.finishAir(inst, result, &.{ty_op.operand});

test/behavior/bugs/1851.zig

@@ -7,7 +7,6 @@ test "allocation and looping over 3-byte integer" {
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
-    if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest;
 
     if (builtin.zig_backend == .stage2_llvm and builtin.os.tag == .macos) {
         return error.SkipZigTest; // TODO

test/behavior/struct.zig

@@ -1351,7 +1351,6 @@ test "under-aligned struct field" {
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
-    if (builtin.zig_backend == .stage2_wasm) return error.SkipZigTest;
 
     const U = extern union {
         fd: i32,