From 0a3e566f57063c42146aa2d64481a7eb1361f96f Mon Sep 17 00:00:00 2001
From: Robin Voetter <robin@voetter.nl>
Date: Sat, 7 Oct 2023 22:11:10 +0200
Subject: [PATCH] spirv: make bitcasts between the same spirv type a no-op

---
 src/codegen/spirv.zig | 8 +++++++-
 test/behavior/for.zig | 4 ----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/codegen/spirv.zig b/src/codegen/spirv.zig
index 293ef5860b..82e172c0d7 100644
--- a/src/codegen/spirv.zig
+++ b/src/codegen/spirv.zig
@@ -2527,7 +2527,12 @@ const DeclGen = struct {
         src_id: IdRef,
     ) !IdRef {
         const mod = self.module;
+        const src_ty_ref = try self.resolveType(src_ty, .direct);
         const dst_ty_ref = try self.resolveType(dst_ty, .direct);
+        if (src_ty_ref == dst_ty_ref) {
+            return src_id;
+        }
+
         const result_id = self.spv.allocId();
 
         // TODO: Some more cases are missing here
@@ -2811,7 +2816,8 @@ const DeclGen = struct {
 
     fn airSliceElemPtr(self: *DeclGen, inst: Air.Inst.Index) !?IdRef {
         const mod = self.module;
-        const bin_op = self.air.instructions.items(.data)[inst].bin_op;
+        const ty_pl = self.air.instructions.items(.data)[inst].ty_pl;
+        const bin_op = self.air.extraData(Air.Bin, ty_pl.payload).data;
         const slice_ty = self.typeOf(bin_op.lhs);
         if (!slice_ty.isVolatilePtr(mod) and self.liveness.isUnused(inst)) return null;
 
diff --git a/test/behavior/for.zig b/test/behavior/for.zig
index 211fba932b..b1fc2f0fb9 100644
--- a/test/behavior/for.zig
+++ b/test/behavior/for.zig
@@ -70,7 +70,6 @@ test "basic for loop" {
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest;
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
     if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
-    if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
 
     const expected_result = [_]u8{ 9, 8, 7, 6, 0, 1, 2, 3 } ** 3;
 
@@ -157,7 +156,6 @@ test "for loop with pointer elem var" {
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
     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;
 
     const source = "abcdefg";
     var target: [source.len]u8 = undefined;
@@ -204,7 +202,6 @@ test "for on slice with allowzero ptr" {
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
     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;
 
     const S = struct {
         fn doTheTest(slice: []const u8) !void {
@@ -344,7 +341,6 @@ test "two slices, one captured by-ref" {
     if (builtin.zig_backend == .stage2_sparc64) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
     if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
-    if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;
 
     var buf: [10]u8 = undefined;
     const slice1: []const u8 = "blah";