From ac7bf53d9486d6c9a079a818dc87891551eaeac1 Mon Sep 17 00:00:00 2001
From: Mick Sayson <mick@sayson.com>
Date: Mon, 6 Jul 2026 17:12:49 -0700
Subject: [PATCH] hardcode opengl float type alignment

fixes compilation of attached test case
---
 src/Type.zig                         |  4 ++--
 test/cases/storage_buffer_opengl.zig | 27 +++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)
 create mode 100644 test/cases/storage_buffer_opengl.zig

diff --git a/src/Type.zig b/src/Type.zig
index 0e54f7c51f36c9a88558c792b7fed439929f68c7..fc867194e3f3ebe2a3a772946a0f57d90d87dbe9 100644
--- a/src/Type.zig
+++ b/src/Type.zig
@@ -1019,8 +1019,8 @@ pub fn abiAlignment(ty: Type, zcu: *const Zcu) Alignment {
             .c_longdouble => cTypeAlign(target, .longdouble),
 
             .f16 => .@"2",
-            .f32 => cTypeAlign(target, .float),
-            .f64 => switch (target.cTypeBitSize(.double)) {
+            .f32 => if (target.os.tag == .opengl) .@"4" else cTypeAlign(target, .float),
+            .f64 => if (target.os.tag == .opengl) .@"8" else switch (target.cTypeBitSize(.double)) {
                 64 => cTypeAlign(target, .double),
                 else => .@"8",
             },
diff --git a/test/cases/storage_buffer_opengl.zig b/test/cases/storage_buffer_opengl.zig
new file mode 100644
index 0000000000000000000000000000000000000000..495cf165a7e1f07bb24c2c621b00c1d8a2a66124
--- /dev/null
+++ b/test/cases/storage_buffer_opengl.zig
@@ -0,0 +1,27 @@
+const std = @import("std");
+
+const RuntimeArray = @SpirvType(.{ .runtime_array = @Vector(4, f32) });
+const Buffer = extern struct {
+    data: RuntimeArray,
+};
+
+const output = @extern(*addrspace(.storage_buffer) Buffer, .{
+    .name = "output",
+    .decoration = .{ .descriptor = .{ .set = 0, .binding = 0 } },
+});
+
+const num_segments = 20;
+
+export fn main() callconv(.{ .spirv_kernel = .{ .x = 1, .y = 1, .z = 1 } }) void {
+    const val = std.spirv.global_invocation_id[0];
+    if (val > num_segments) return;
+    var val_f: f32 = @floatFromInt(val);
+    val_f /= num_segments;
+    output.data[val] = .{ val_f, val_f, 0, 1 };
+}
+
+// compile
+// output_mode=Obj
+// backend=auto
+// target=spirv32-opengl
+// emit_bin=true
-- 
2.54.0