codegen: take gc roots (and alloca alignment) more seriously

Due to limitations in the LLVM implementation, we are forced to emit fairly bad code here. But we need to make sure it is still correct with respect to GC rooting. Fixes #54720
JuliaLang · Aug 1, 2024 · bd84693 · bd84693
1 parent f4a022c
commit bd84693
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Showing 4 changed files with 112 additions and 78 deletions.
diff --git a/src/ccall.cpp b/src/ccall.cpp
@@ -554,8 +554,8 @@ static Value *julia_to_native(
     // pass the address of an alloca'd thing, not a box
     // since those are immutable.
     Value *slot = emit_static_alloca(ctx, to);
-    unsigned align = julia_alignment(jlto);
-    cast<AllocaInst>(slot)->setAlignment(Align(align));
+    Align align(julia_alignment(jlto));
+    cast<AllocaInst>(slot)->setAlignment(align);
     setName(ctx.emission_context, slot, "native_convert_buffer");
     if (!jvinfo.ispointer()) {
         jl_aliasinfo_t ai = jl_aliasinfo_t::fromTBAA(ctx, jvinfo.tbaa);
@@ -2230,7 +2230,7 @@ jl_cgval_t function_sig_t::emit_a_ccall(
                 Value *strct = emit_allocobj(ctx, (jl_datatype_t*)rt, true);
                 setName(ctx.emission_context, strct, "ccall_ret_box");
                 MDNode *tbaa = jl_is_mutable(rt) ? ctx.tbaa().tbaa_mutab : ctx.tbaa().tbaa_immut;
-                int boxalign = julia_alignment(rt);
+                Align boxalign(julia_alignment(rt));
                 // copy the data from the return value to the new struct
                 const DataLayout &DL = ctx.builder.GetInsertBlock()->getModule()->getDataLayout();
                 auto resultTy = result->getType();
@@ -2240,8 +2240,8 @@ jl_cgval_t function_sig_t::emit_a_ccall(
                     // When this happens, cast through memory.
                     auto slot = emit_static_alloca(ctx, resultTy);
                     setName(ctx.emission_context, slot, "type_pun_slot");
-                    slot->setAlignment(Align(boxalign));
-                    ctx.builder.CreateAlignedStore(result, slot, Align(boxalign));
+                    slot->setAlignment(boxalign);
+                    ctx.builder.CreateAlignedStore(result, slot, boxalign);
                     jl_aliasinfo_t ai = jl_aliasinfo_t::fromTBAA(ctx, tbaa);
                     emit_memcpy(ctx, strct, ai, slot, ai, rtsz, boxalign, boxalign);
                 }