From c78ebeb44ce078a165e3302b629432eeee6a656d Mon Sep 17 00:00:00 2001
From: David Rubin <daviru007@icloud.com>
Date: Fri, 5 Jul 2024 23:00:55 -0700
Subject: [PATCH] riscv: implement `ptr_slice_ptr_ptr`

just one step closer to allocation
---
 lib/std/builtin.zig          | 1 +
 src/arch/riscv64/CodeGen.zig | 9 +++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/lib/std/builtin.zig b/lib/std/builtin.zig
index a600f055df..86f8da6cd4 100644
--- a/lib/std/builtin.zig
+++ b/lib/std/builtin.zig
@@ -776,6 +776,7 @@ pub fn default_panic(msg: []const u8, error_return_trace: ?*StackTrace, ret_addr
 
     if (builtin.zig_backend == .stage2_riscv64) {
         std.debug.print("panic: {s}\n", .{msg});
+        @breakpoint();
         std.posix.exit(127);
     }
 
diff --git a/src/arch/riscv64/CodeGen.zig b/src/arch/riscv64/CodeGen.zig
index 56815f63b9..6ca4f37695 100644
--- a/src/arch/riscv64/CodeGen.zig
+++ b/src/arch/riscv64/CodeGen.zig
@@ -3433,8 +3433,13 @@ fn airPtrSliceLenPtr(func: *Func, inst: Air.Inst.Index) !void {
 
 fn airPtrSlicePtrPtr(func: *Func, inst: Air.Inst.Index) !void {
     const ty_op = func.air.instructions.items(.data)[@intFromEnum(inst)].ty_op;
-    const result: MCValue = if (func.liveness.isUnused(inst)) .unreach else return func.fail("TODO implement ptr_slice_ptr_ptr for {}", .{func.target.cpu.arch});
-    return func.finishAir(inst, result, .{ ty_op.operand, .none, .none });
+
+    const opt_mcv = try func.resolveInst(ty_op.operand);
+    const dst_mcv = if (func.reuseOperand(inst, ty_op.operand, 0, opt_mcv))
+        opt_mcv
+    else
+        try func.copyToNewRegister(inst, opt_mcv);
+    return func.finishAir(inst, dst_mcv, .{ ty_op.operand, .none, .none });
 }
 
 fn airSliceElemVal(func: *Func, inst: Air.Inst.Index) !void {