build: fix LLVM 18 build on GCC 15

See also: referenced LLVM pull requests in patch files.

Author: XeniaLu

build-scripts/build_llvm.py

@@ -23,9 +23,15 @@ def clone_llvm(dst_dir, llvm_repo, llvm_branch):
 
     if not llvm_dir.exists():
         GIT_CLONE_CMD = f"git clone --depth 1 --branch {llvm_branch} {llvm_repo} llvm"
-        print(GIT_CLONE_CMD)
+        print(f"cd {dst_dir} && {GIT_CLONE_CMD}")
         subprocess.check_output(shlex.split(GIT_CLONE_CMD), cwd=dst_dir)
 
+        patch_dir = pathlib.Path(__file__).parent.joinpath("llvm-patches").resolve()
+        for patch_file in patch_dir.glob("*.patch"):
+            cmd = f"git apply {patch_file}"
+            print(f"cd {llvm_dir} && {cmd}")
+            subprocess.check_output(shlex.split(cmd), cwd=llvm_dir)
+
     return llvm_dir
 
 

build-scripts/llvm-patches/0001_Add_cstdint_to_SmallVector_101761.patch

@@ -0,0 +1,28 @@
+From aa01bd3a71399edb05fa9b0ab8e0bd35585aa1c5 Mon Sep 17 00:00:00 2001
+From: Sam James <[email protected]>
+Date: Fri, 2 Aug 2024 23:07:21 +0100
+Subject: [PATCH 1/2] Add `<cstdint>` to SmallVector (#101761)
+
+SmallVector uses `uint32_t`, `uint64_t` without including `<cstdint>`
+which fails to build w/ GCC 15 after a change in libstdc++ [0]
+
+[0] https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=3a817a4a5a6d94da9127af3be9f84a74e3076ee2
+---
+ llvm/include/llvm/ADT/SmallVector.h | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/llvm/include/llvm/ADT/SmallVector.h b/llvm/include/llvm/ADT/SmallVector.h
+index e34702bdb..1c0f3465b 100644
+--- a/llvm/include/llvm/ADT/SmallVector.h
++++ b/llvm/include/llvm/ADT/SmallVector.h
+@@ -19,6 +19,7 @@
+ #include <algorithm>
+ #include <cassert>
+ #include <cstddef>
++#include <cstdint>
+ #include <cstdlib>
+ #include <cstring>
+ #include <functional>
+-- 
+2.51.0
+

build-scripts/llvm-patches/0002_Add_missing_include_to_X86MCTargetDesc.h_123320.patch

@@ -0,0 +1,32 @@
+From 3ba14e5ea319e138f8d0f5c06fd2f76d425e4093 Mon Sep 17 00:00:00 2001
+From: Stephan Hageboeck <[email protected]>
+Date: Mon, 20 Jan 2025 17:52:47 +0100
+Subject: [PATCH 2/2] Add missing include to X86MCTargetDesc.h (#123320)
+
+In gcc-15, explicit includes of `<cstdint>` are required when fixed-size
+integers are used. In this file, this include only happened as a side
+effect of including SmallVector.h
+
+Although llvm compiles fine, the root-project would benefit from
+explicitly including it here, so we can backport the patch.
+
+Maybe interesting for @hahnjo and @vgvassilev
+---
+ llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.h | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.h b/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.h
+index d0530bd4d..10b59462a 100644
+--- a/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.h
++++ b/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.h
+@@ -13,6 +13,7 @@
+ #ifndef LLVM_LIB_TARGET_X86_MCTARGETDESC_X86MCTARGETDESC_H
+ #define LLVM_LIB_TARGET_X86_MCTARGETDESC_X86MCTARGETDESC_H
+ 
++#include <cstdint>
+ #include <memory>
+ #include <string>
+ 
+-- 
+2.51.0
+