[Serialization] Read the initializer for interesting static variables before consuming it

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -4186,12 +4186,35 @@ void ASTReader::PassInterestingDeclsToConsumer() {
     GetDecl(ID);
   EagerlyDeserializedDecls.clear();
 
-  while (!PotentiallyInterestingDecls.empty()) {
-    Decl *D = PotentiallyInterestingDecls.front();
-    PotentiallyInterestingDecls.pop_front();
+  auto ConsumingPotentialInterestingDecls = [this]() {
+    while (!PotentiallyInterestingDecls.empty()) {
+      Decl *D = PotentiallyInterestingDecls.front();
+      PotentiallyInterestingDecls.pop_front();
+      if (isConsumerInterestedIn(D))
+        PassInterestingDeclToConsumer(D);
+    }
+  };
+  std::deque<Decl *> MaybeInterestingDecls =
+      std::move(PotentiallyInterestingDecls);
+  assert(PotentiallyInterestingDecls.empty());
+  while (!MaybeInterestingDecls.empty()) {
+    Decl *D = MaybeInterestingDecls.front();
+    MaybeInterestingDecls.pop_front();
+    // Since we load the variable's initializers lazily, it'd be problematic
+    // if the initializers dependent on each other. So here we try to load the
+    // initializers of static variables to make sure they are passed to code
+    // generator by order. If we read anything interesting, we would consume
+    // that before emitting the current declaration.
+    if (auto *VD = dyn_cast<VarDecl>(D);
+        VD && VD->isFileVarDecl() && !VD->isExternallyVisible())
+      VD->getInit();
+    ConsumingPotentialInterestingDecls();
     if (isConsumerInterestedIn(D))
       PassInterestingDeclToConsumer(D);
   }
+
+  // If we add any new potential interesting decl in the last call, consume it.
+  ConsumingPotentialInterestingDecls();
 }
 
 void ASTReader::loadDeclUpdateRecords(PendingUpdateRecord &Record) {

clang/test/Modules/pr91418.cppm

@@ -0,0 +1,65 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20 -x c++-header %t/foo.h \
+// RUN:     -emit-pch -o %t/foo.pch
+// RUN: %clang_cc1 -triple %itanium_abi_triple -std=c++20 %t/use.cpp -include-pch \
+// RUN:     %t/foo.pch -emit-llvm -o - | FileCheck %t/use.cpp
+
+//--- foo.h
+#ifndef FOO_H
+#define FOO_H
+typedef float __m128 __attribute__((__vector_size__(16), __aligned__(16)));
+
+static __inline__ __m128 __attribute__((__always_inline__, __min_vector_width__(128)))
+_mm_setr_ps(float __z, float __y, float __x, float __w)
+{
+  return __extension__ (__m128){ __z, __y, __x, __w };
+}
+
+typedef __m128 VR;
+
+inline VR MakeVR( float X, float Y, float Z, float W )
+{
+ return _mm_setr_ps( X, Y, Z, W );
+}
+
+extern "C" float sqrtf(float);
+
+namespace VectorSinConstantsSSE
+{
+  float a = (16 * sqrtf(0.225f));
+  VR A = MakeVR(a, a, a, a);
+  static const float b = (16 * sqrtf(0.225f));
+  static const VR B = MakeVR(b, b, b, b);
+}
+
+#endif // FOO_H
+
+//--- use.cpp
+#include "foo.h"
+float use() {
+    return VectorSinConstantsSSE::A[0] + VectorSinConstantsSSE::A[1] +
+           VectorSinConstantsSSE::A[2] + VectorSinConstantsSSE::A[3] +
+           VectorSinConstantsSSE::B[0] + VectorSinConstantsSSE::B[1] +
+           VectorSinConstantsSSE::B[2] + VectorSinConstantsSSE::B[3];
+}
+
+// CHECK: define{{.*}}@__cxx_global_var_init(
+// CHECK: store{{.*}}, ptr @_ZN21VectorSinConstantsSSE1aE
+
+// CHECK: define{{.*}}@__cxx_global_var_init.1(
+// CHECK: store{{.*}}, ptr @_ZN21VectorSinConstantsSSE1AE
+
+// CHECK: define{{.*}}@__cxx_global_var_init.2(
+// CHECK: store{{.*}}, ptr @_ZN21VectorSinConstantsSSEL1BE
+
+// CHECK: define{{.*}}@__cxx_global_var_init.3(
+// CHECK: store{{.*}}, ptr @_ZN21VectorSinConstantsSSEL1bE
+
+// CHECK: @_GLOBAL__sub_I_use.cpp
+// CHECK: call{{.*}}@__cxx_global_var_init(
+// CHECK: call{{.*}}@__cxx_global_var_init.1(
+// CHECK: call{{.*}}@__cxx_global_var_init.3(
+// CHECK: call{{.*}}@__cxx_global_var_init.2(