From e788dfa142f27717df1258009cadb61f314610dd Mon Sep 17 00:00:00 2001
From: Robin Voetter <robin@voetter.nl>
Date: Sat, 10 Dec 2022 14:07:52 +0100
Subject: [PATCH] spirv: string literals

Implements lowering string literal constants in the SPIR-V backend
---
 src/codegen/spirv.zig | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/codegen/spirv.zig b/src/codegen/spirv.zig
index f81a248f63..7df4360c41 100644
--- a/src/codegen/spirv.zig
+++ b/src/codegen/spirv.zig
@@ -461,8 +461,9 @@ pub const DeclGen = struct {
                 .repeated => {
                     const elem_val = val.castTag(.repeated).?.data;
                     const elem_ty = ty.elemType();
-                    const len = @intCast(u32, ty.arrayLenIncludingSentinel()); // TODO: limit spir-v to 32 bit arrays in a more elegant way.
-                    const constituents = try self.spv.gpa.alloc(IdRef, len);
+                    const len = @intCast(u32, ty.arrayLen());
+                    const total_len = @intCast(u32, ty.arrayLenIncludingSentinel()); // TODO: limit spir-v to 32 bit arrays in a more elegant way.
+                    const constituents = try self.spv.gpa.alloc(IdRef, total_len);
                     defer self.spv.gpa.free(constituents);
 
                     const elem_val_id = self.spv.allocId();
@@ -480,6 +481,31 @@ pub const DeclGen = struct {
                         .constituents = constituents,
                     });
                 },
+                .str_lit => {
+                    // TODO: This is very efficient code generation, should probably implement constant caching for this.
+                    const str_lit = val.castTag(.str_lit).?.data;
+                    const bytes = self.module.string_literal_bytes.items[str_lit.index..][0..str_lit.len];
+                    const elem_ty = ty.elemType();
+                    const elem_ty_id = try self.resolveTypeId(elem_ty);
+                    const len = @intCast(u32, ty.arrayLen());
+                    const total_len = @intCast(u32, ty.arrayLenIncludingSentinel());
+                    const constituents = try self.spv.gpa.alloc(IdRef, total_len);
+                    defer self.spv.gpa.free(constituents);
+                    for (bytes) |byte, i| {
+                        constituents[i] = self.spv.allocId();
+                        try self.spv.emitConstant(elem_ty_id, constituents[i], .{ .uint32 = byte });
+                    }
+                    if (ty.sentinel()) |sentinel| {
+                        constituents[len] = self.spv.allocId();
+                        const byte = @intCast(u8, sentinel.toUnsignedInt(target));
+                        try self.spv.emitConstant(elem_ty_id, constituents[len], .{ .uint32 = byte });
+                    }
+                    try section.emit(self.spv.gpa, .OpConstantComposite, .{
+                        .id_result_type = result_ty_id,
+                        .id_result = result_id,
+                        .constituents = constituents,
+                    });
+                },
                 else => return self.todo("array constant with tag {s}", .{@tagName(val.tag())}),
             },
             .Vector => switch (val.tag()) {