[llvm] [bazel] Port #149198 (PR #150352)

[Jordan Rupprecht via llvm-commits]

https://github.com/rupprecht created https://github.com/llvm/llvm-project/pull/150352

None

>From 5450b0f50d58f3d6fcfa7dbc8fccda51c2fd9ded Mon Sep 17 00:00:00 2001
From: Jordan Rupprecht <rupprecht at google.com>
Date: Wed, 23 Jul 2025 18:22:56 -0700
Subject: [PATCH] [bazel] Port #149198

---
 utils/bazel/llvm_configs/abi-breaking.h.cmake | 33 +++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/utils/bazel/llvm_configs/abi-breaking.h.cmake b/utils/bazel/llvm_configs/abi-breaking.h.cmake
index 2d27e02b1d545..330f36011d231 100644
--- a/utils/bazel/llvm_configs/abi-breaking.h.cmake
+++ b/utils/bazel/llvm_configs/abi-breaking.h.cmake
@@ -12,12 +12,41 @@
 #ifndef LLVM_ABI_BREAKING_CHECKS_H
 #define LLVM_ABI_BREAKING_CHECKS_H
 
+// llvm-config.h is required for LLVM_ENABLE_LLVM_EXPORT_ANNOTATIONS
+#include "llvm/Config/llvm-config.h"
+
 /* Define to enable checks that alter the LLVM C++ ABI */
 #cmakedefine01 LLVM_ENABLE_ABI_BREAKING_CHECKS
 
 /* Define to enable reverse iteration of unordered llvm containers */
 #cmakedefine01 LLVM_ENABLE_REVERSE_ITERATION
 
+#if !defined(__has_attribute)
+#define __has_attribute(attribute) 0
+#endif
+
+// Properly annotate EnableABIBreakingChecks or DisableABIBreakingChecks for
+// export from shared library.
+// TODO(https://github.com/llvm/llvm-project/issues/145406): eliminate need for
+// two preprocessor definitions to gate LLVM_ABI macro definitions.
+#if defined(LLVM_BUILD_STATIC) || !defined(LLVM_ENABLE_LLVM_EXPORT_ANNOTATIONS)
+#define ABI_BREAKING_EXPORT_ABI
+#else
+#if defined(_WIN32)
+#if defined(LLVM_EXPORTS)
+#define ABI_BREAKING_EXPORT_ABI __declspec(dllexport)
+#else
+#define ABI_BREAKING_EXPORT_ABI __declspec(dllimport)
+#endif
+#else
+#if __has_attribute(visibility)
+#define ABI_BREAKING_EXPORT_ABI __attribute__((__visibility__("default")))
+#else
+#define ABI_BREAKING_EXPORT_ABI
+#endif
+#endif
+#endif
+
 /* Allow selectively disabling link-time mismatch checking so that header-only
    ADT content from LLVM can be used without linking libSupport. */
 #if !defined(LLVM_DISABLE_ABI_BREAKING_CHECKS_ENFORCING) || !LLVM_DISABLE_ABI_BREAKING_CHECKS_ENFORCING
@@ -43,12 +72,12 @@
 #endif
 namespace llvm {
 #if LLVM_ENABLE_ABI_BREAKING_CHECKS
-extern int EnableABIBreakingChecks;
+ABI_BREAKING_EXPORT_ABI extern int EnableABIBreakingChecks;
 LLVM_HIDDEN_VISIBILITY
 __attribute__((weak)) int *VerifyEnableABIBreakingChecks =
     &EnableABIBreakingChecks;
 #else
-extern int DisableABIBreakingChecks;
+ABI_BREAKING_EXPORT_ABI extern int DisableABIBreakingChecks;
 LLVM_HIDDEN_VISIBILITY
 __attribute__((weak)) int *VerifyDisableABIBreakingChecks =
     &DisableABIBreakingChecks;