Fixes for bitcast bugs with LLVM 17 / opaque pointers (#54548)

Skip setName on folded inputs, and ensure
the correct pointer address space is used.

(cherry picked from commit baca8ba)

Author: maleadt

src/intrinsics.cpp

@@ -629,10 +629,24 @@ static jl_cgval_t generic_bitcast(jl_codectx_t &ctx, const jl_cgval_t *argv)
             setName(ctx.emission_context, vx, "bitcast_coercion");
         } else if (!vxt->isPointerTy() && llvmt->isPointerTy()) {
             vx = emit_inttoptr(ctx, vx, llvmt);
-            setName(ctx.emission_context, vx, "bitcast_coercion");
+            if (isa<Instruction>(vx) && !vx->hasName())
+                // emit_inttoptr may undo an PtrToInt
+                setName(ctx.emission_context, vx, "bitcast_coercion");
+        } else if (vxt->isPointerTy() && llvmt->isPointerTy()) {
+            // emit_bitcast preserves the origin address space, which we can't have here
+            #if JL_LLVM_VERSION >= 170000
+            vx = ctx.builder.CreateAddrSpaceCast(vx, llvmt);
+            #else
+            vx = ctx.builder.CreatePointerBitCastOrAddrSpaceCast(vx, llvmt);
+            #endif
+            if (isa<Instruction>(vx) && !vx->hasName())
+                // cast may have been folded
+                setName(ctx.emission_context, vx, "bitcast_coercion");
         } else {
             vx = emit_bitcast(ctx, vx, llvmt);
-            setName(ctx.emission_context, vx, "bitcast_coercion");
+            if (isa<Instruction>(vx) && !vx->hasName())
+                // emit_bitcast may undo another bitcast
+                setName(ctx.emission_context, vx, "bitcast_coercion");
         }
     }