From 7679289e17511c76f729eef3608c23f4ee296430 Mon Sep 17 00:00:00 2001
From: gbaraldi <baraldigabriel@gmail.com>
Date: Tue, 12 Aug 2025 11:16:55 -0300
Subject: [PATCH] Fix compile time regression for null ptr comparisons

---
 src/cgutils.cpp | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/src/cgutils.cpp b/src/cgutils.cpp
index 97a58f8aa419c..e9b2bc3aa2ed0 100644
--- a/src/cgutils.cpp
+++ b/src/cgutils.cpp
@@ -1601,6 +1601,18 @@ static void undef_var_error_ifnot(jl_codectx_t &ctx, Value *ok, jl_sym_t *name,
     ctx.builder.SetInsertPoint(ifok);
 }
 
+
+static bool has_known_null_nullptr(Type *T)
+{
+    if (auto PT = cast<PointerType>(T)) {
+        auto addrspace = PT->getAddressSpace();
+        if (addrspace == AddressSpace::Generic || (AddressSpace::FirstSpecial <= addrspace && addrspace <= AddressSpace::LastSpecial)) {
+            return true;
+        }
+    }
+    return false;
+}
+
 // ctx.builder.CreateIsNotNull(v) lowers incorrectly in non-standard
 // address spaces where null is not zero
 // TODO: adapt to https://github.com/llvm/llvm-project/pull/131557 once merged
@@ -1608,10 +1620,11 @@ static Value *null_pointer_cmp(jl_codectx_t &ctx, Value *v)
 {
     ++EmittedNullchecks;
     Type *T = v->getType();
-    return ctx.builder.CreateICmpNE(
-            v,
-            ctx.builder.CreateAddrSpaceCast(
-                Constant::getNullValue(ctx.builder.getPtrTy(0)), T));
+    if (has_known_null_nullptr(T))
+        return ctx.builder.CreateIsNotNull(v);
+    else
+        return ctx.builder.CreateICmpNE(v, ctx.builder.CreateAddrSpaceCast(
+            Constant::getNullValue(ctx.builder.getPtrTy(0)), T));
 }