From 28203e182f0d74577fee90d4fccd52fa98f72f07 Mon Sep 17 00:00:00 2001
From: Tsukasa OI <floss_rust@irq.a4lg.com>
Date: Fri, 19 Sep 2025 04:14:10 +0000
Subject: [PATCH] rustc_codegen_llvm: Simplify
 `update_target_reliable_float_cfg`

This commit simplifies floating type handling through
`update_target_reliable_float_cfg` based on several facts:

1.  Major changes in behavior normally occurs only
    on the major LLVM upgrade.
2.  The first release of LLVM 20.x.x is 20.1.0.

Due to the first fact, we can normally ignore minor and patch releases
of LLVM and we can remove obscure variables like `lt_xx_x_x` (still,
there is a case where checking for patch version is required).

The second fact is missed when the minimum LLVM version is raised to
LLVM 20 and one "fixed in LLVM 20" case can be safely removed.
---
 compiler/rustc_codegen_llvm/src/llvm_util.rs | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index adb1ac09a633..a3b1de9c3878 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -364,26 +364,25 @@ fn update_target_reliable_float_cfg(sess: &Session, cfg: &mut TargetConfig) {
     let target_abi = &sess.target.options.abi;
     let target_pointer_width = sess.target.pointer_width;
     let version = get_version();
-    let lt_20_1_0 = version < (20, 1, 0);
-    let lt_20_1_1 = version < (20, 1, 1);
-    let lt_21_0_0 = version < (21, 0, 0);
+    let (major, _, _) = version;
 
     cfg.has_reliable_f16 = match (target_arch, target_os) {
         // LLVM crash without neon <https://github.com/llvm/llvm-project/issues/129394> (fixed in LLVM 20.1.1)
         (Arch::AArch64, _)
-            if !cfg.target_features.iter().any(|f| f.as_str() == "neon") && lt_20_1_1 =>
+            if !cfg.target_features.iter().any(|f| f.as_str() == "neon")
+                && version < (20, 1, 1) =>
         {
             false
         }
         // Unsupported <https://github.com/llvm/llvm-project/issues/94434>
         (Arch::Arm64EC, _) => false,
         // Selection failure <https://github.com/llvm/llvm-project/issues/50374> (fixed in llvm21)
-        (Arch::S390x, _) if lt_21_0_0 => false,
+        (Arch::S390x, _) if major < 21 => false,
         // MinGW ABI bugs <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115054>
         (Arch::X86_64, Os::Windows) if *target_env == Env::Gnu && *target_abi != Abi::Llvm => false,
         // Infinite recursion <https://github.com/llvm/llvm-project/issues/97981>
         (Arch::CSky, _) => false,
-        (Arch::Hexagon, _) if lt_21_0_0 => false, // (fixed in llvm21)
+        (Arch::Hexagon, _) if major < 21 => false, // (fixed in llvm21)
         (Arch::PowerPC | Arch::PowerPC64, _) => false,
         (Arch::Sparc | Arch::Sparc64, _) => false,
         (Arch::Wasm32 | Arch::Wasm64, _) => false,
@@ -397,7 +396,7 @@ fn update_target_reliable_float_cfg(sess: &Session, cfg: &mut TargetConfig) {
         // Unsupported <https://github.com/llvm/llvm-project/issues/94434>
         (Arch::Arm64EC, _) => false,
         // Selection bug <https://github.com/llvm/llvm-project/issues/96432> (fixed in LLVM 20.1.0)
-        (Arch::Mips64 | Arch::Mips64r6, _) if lt_20_1_0 => false,
+        (Arch::Mips64 | Arch::Mips64r6, _) if version < (20, 1, 0) => false,
         // Selection bug <https://github.com/llvm/llvm-project/issues/95471>. This issue is closed
         // but basic math still does not work.
         (Arch::Nvptx64, _) => false,
@@ -410,7 +409,7 @@ fn update_target_reliable_float_cfg(sess: &Session, cfg: &mut TargetConfig) {
         (Arch::Sparc, _) => false,
         // Stack alignment bug <https://github.com/llvm/llvm-project/issues/77401>. NB: tests may
         // not fail if our compiler-builtins is linked. (fixed in llvm21)
-        (Arch::X86, _) if lt_21_0_0 => false,
+        (Arch::X86, _) if major < 21 => false,
         // MinGW ABI bugs <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115054>
         (Arch::X86_64, Os::Windows) if *target_env == Env::Gnu && *target_abi != Abi::Llvm => false,
         // There are no known problems on other platforms, so the only requirement is that symbols