downloads: upgrade LLVM 18.0.8 -> 19.1.6

As part of this we also modernize the BOLT apply settings to follow
the recommendations at
https://llvm.org/devmtg/2024-03/slides/practical-use-of-bolt.pdf.

This includes enabling support for loading hot code from a huge page
at runtime. This should _just work_ and could result in perf wins via
improved iTLB hit rate, etc.

cpython-unix/build-cpython.sh

@@ -259,9 +259,12 @@ if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_11}" ]; then
     patch -p1 -i ${ROOT}/patch-pwd-remove-conditional.patch
 fi
 
-# Adjust BOLT flags to yield better behavior. See inline details in patch.
 if [ -n "${PYTHON_MEETS_MINIMUM_VERSION_3_12}" ]; then
+    # Adjust BOLT flags to yield better behavior. See inline details in patch.
     patch -p1 -i ${ROOT}/patch-configure-bolt-flags.patch
+
+    # Adjust BOLT application flags to make use of modern LLVM features.
+    patch -p1 -i ${ROOT}/patch-configure-bolt-apply-flags.patch
 fi
 
 # The optimization make targets are both phony and non-phony. This leads

cpython-unix/patch-configure-bolt-apply-flags.patch

@@ -0,0 +1,23 @@
+diff --git a/configure.ac b/configure.ac
+index ee034e5a962..f1a69b7d4a7 100644
+--- a/configure.ac
++++ b/configure.ac
+@@ -2183,8 +2183,9 @@ then
+     [m4_normalize("
+      -update-debug-sections
+      -reorder-blocks=ext-tsp
+-     -reorder-functions=hfsort+
++     -reorder-functions=cdsort
+      -split-functions
++     -split-strategy=cdsplit
+      -icf=1
+      -inline-all
+      -split-eh
+@@ -2196,6 +2197,7 @@ then
+      -dyno-stats
+      -use-gnu-stack
+      -frame-opt=hot
++     -hugify
+    ")]
+   )
+ fi

pythonbuild/downloads.py

@@ -185,25 +185,25 @@
         "version": "14.0.3+20220508",
     },
     # Remember to update LLVM_URL in src/release.rs whenever upgrading.
-    "llvm-18-x86_64-linux": {
-        "url": "https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20240713/llvm-18.0.8+20240713-gnu_only-x86_64-unknown-linux-gnu.tar.zst",
-        "size": 242840506,
-        "sha256": "080c233fc7d75031b187bbfef62a4f9abc01188effb0c68fbc7dc4bc7370ee5b",
-        "version": "18.0.8+20240713",
+    "llvm-19-x86_64-linux": {
+        "url": "https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20241231/llvm-19.1.6+20241231-gnu_only-x86_64-unknown-linux-gnu.tar.zst",
+        "size": 251277644,
+        "sha256": "900bbb464d430e960ea97150e073395ae865332ce403e7c1e8f76640cab5e852",
+        "version": "19.1.6+20241231",
     },
     # Remember to update LLVM_URL in src/release.rs whenever upgrading.
     "llvm-aarch64-macos": {
-        "url": "https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20240713/llvm-18.0.8+20240713-aarch64-apple-darwin.tar.zst",
-        "size": 136598617,
-        "sha256": "320da8d639186e020e7d54cdc35b7a5473b36cef08fdf7b22c03b59a273ba593",
-        "version": "18.0.8+20240713",
+        "url": "https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20241231/llvm-19.1.6+20241231-aarch64-apple-darwin.tar.zst",
+        "size": 143884729,
+        "sha256": "c0252c7ebe0b20125fe592a12d43a693fcab0bfa3bec9def6b96b97087e0f765",
+        "version": "19.1.6+20241231",
     },
     # Remember to update LLVM_URL in src/release.rs whenever upgrading.
     "llvm-x86_64-macos": {
-        "url": "https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20240713/llvm-18.0.8+20240713-x86_64-apple-darwin.tar.zst",
-        "size": 136599290,
-        "sha256": "3032161d1cadb8996b07fe5762444c956842b5a7d798b2fcfe5a04574fdf7549",
-        "version": "18.0.8+20240713",
+        "url": "https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20241231/llvm-19.1.6+20241231-x86_64-apple-darwin.tar.zst",
+        "size": 143113277,
+        "sha256": "e990dea9ff89e4202d358b477a43f2bd128b244926534b7c8bb29feeaada994e",
+        "version": "19.1.6+20241231",
     },
     "m4": {
         "url": "https://ftp.gnu.org/gnu/m4/m4-1.4.19.tar.xz",

pythonbuild/utils.py

@@ -426,7 +426,7 @@ def clang_toolchain(host_platform: str, target_triple: str) -> str:
         if "musl" in target_triple:
             return "llvm-14-x86_64-linux"
         else:
-            return "llvm-18-x86_64-linux"
+            return "llvm-19-x86_64-linux"
     elif host_platform == "macos":
         if platform.mac_ver()[2] == "arm64":
             return "llvm-aarch64-macos"

src/release.rs

@@ -575,14 +575,14 @@ pub fn produce_install_only_stripped(tar_gz_path: &Path, llvm_dir: &Path) -> Res
 static LLVM_URL: Lazy<Url> = Lazy::new(|| {
     if cfg!(target_os = "macos") {
         if std::env::consts::ARCH == "aarch64" {
-            Url::parse("https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20240713/llvm-18.0.8+20240713-aarch64-apple-darwin.tar.zst").unwrap()
+            Url::parse("https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20241231/llvm-19.1.6+20241231-aarch64-apple-darwin.tar.zst").unwrap()
         } else if std::env::consts::ARCH == "x86_64" {
-            Url::parse("https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20240713/llvm-18.0.8+20240713-x86_64-apple-darwin.tar.zst").unwrap()
+            Url::parse("https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20241231/llvm-19.1.6+20241231-x86_64-apple-darwin.tar.zst").unwrap()
         } else {
             panic!("unsupported macOS architecture");
         }
     } else if cfg!(target_os = "linux") {
-        Url::parse("https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20240713/llvm-18.0.8+20240713-gnu_only-x86_64-unknown-linux-gnu.tar.zst").unwrap()
+        Url::parse("https://github.com/indygreg/toolchain-tools/releases/download/toolchain-bootstrap%2F20241231/llvm-19.1.6+20241231-gnu_only-x86_64-unknown-linux-gnu.tar.zst").unwrap()
     } else {
         panic!("unsupported platform");
     }