From c1229507e29e5c44b6f23d6f2afb5d55e7fb9606 Mon Sep 17 00:00:00 2001
From: ARATA Mizuki <minorinoki@gmail.com>
Date: Wed, 25 Dec 2024 22:50:46 +0900
Subject: [PATCH] Fix LLVM version detection

With a recent LLVM, `llc -version` emits the version on the first line
if the vendor is set.  It emits the version on the second line
otherwise.

Therefore, we need to check the both lines to detect the version.

GHC now emits a warning if it fails to detect the LLVM version,
so we can notice if the output of `llc -version` changes in the future.

Also, the warning for using LLVM < 10 on s390x is removed, because
we assume LLVM >= 13 now.

This fixes the definition of __GLASGOW_HASKELL_LLVM__ macro.

Fixes #25606

(cherry picked from commit a928c326011f1a6bef3289a4c36d4e19b5951229)
---
 compiler/GHC/CmmToLlvm.hs      | 14 ++++++++------
 compiler/GHC/SysTools/Tasks.hs | 13 ++++++++-----
 docs/users_guide/phases.rst    |  2 +-
 3 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/compiler/GHC/CmmToLlvm.hs b/compiler/GHC/CmmToLlvm.hs
index ecf111c636..76541c477c 100644
--- a/compiler/GHC/CmmToLlvm.hs
+++ b/compiler/GHC/CmmToLlvm.hs
@@ -38,7 +38,7 @@ import GHC.Utils.Logger
 import qualified GHC.Data.Stream as Stream
 
 import Control.Monad ( when, forM_ )
-import Data.Maybe ( fromMaybe, catMaybes )
+import Data.Maybe ( fromMaybe, catMaybes, isNothing )
 import System.IO
 
 -- -----------------------------------------------------------------------------
@@ -68,11 +68,13 @@ llvmCodeGen logger cfg h cmm_stream
            "up to" <+> text (llvmVersionStr supportedLlvmVersionUpperBound) <+> "(non inclusive) is supported." <+>
            "System LLVM version: " <> text (llvmVersionStr ver) $$
            "We will try though..."
-         let isS390X = platformArch (llvmCgPlatform cfg)  == ArchS390X
-         let major_ver = head . llvmVersionList $ ver
-         when (isS390X && major_ver < 10 && doWarn) $ putMsg logger $
-           "Warning: For s390x the GHC calling convention is only supported since LLVM version 10." <+>
-           "You are using LLVM version: " <> text (llvmVersionStr ver)
+
+       when (isNothing mb_ver) $ do
+         let doWarn = llvmCgDoWarn cfg
+         when doWarn $ putMsg logger $
+           "Failed to detect LLVM version!" $$
+           "Make sure LLVM is installed correctly." $$
+           "We will try though..."
 
        -- HACK: the Nothing case here is potentially wrong here but we
        -- currently don't use the LLVM version to guide code generation
diff --git a/compiler/GHC/SysTools/Tasks.hs b/compiler/GHC/SysTools/Tasks.hs
index 7cd5188d5f..165e1602cf 100644
--- a/compiler/GHC/SysTools/Tasks.hs
+++ b/compiler/GHC/SysTools/Tasks.hs
@@ -236,14 +236,17 @@ figureLlvmVersion logger dflags = traceToolCommand logger "llc" $ do
               (pin, pout, perr, p) <- runInteractiveProcess pgm args'
                                               Nothing Nothing
               {- > llc -version
-                  LLVM (http://llvm.org/):
-                    LLVM version 3.5.2
+                  <vendor> LLVM version 15.0.7
                     ...
+                  OR
+                  LLVM (http://llvm.org/):
+                    LLVM version 14.0.6
               -}
               hSetBinaryMode pout False
-              _     <- hGetLine pout
-              vline <- hGetLine pout
-              let mb_ver = parseLlvmVersion vline
+              line1 <- hGetLine pout
+              mb_ver <- case parseLlvmVersion line1 of
+                mb_ver@(Just _) -> return mb_ver
+                Nothing -> parseLlvmVersion <$> hGetLine pout -- Try the second line
               hClose pin
               hClose pout
               hClose perr
diff --git a/docs/users_guide/phases.rst b/docs/users_guide/phases.rst
index 6a2d4b3c20..9ccd2aa034 100644
--- a/docs/users_guide/phases.rst
+++ b/docs/users_guide/phases.rst
@@ -474,7 +474,7 @@ defined by your local GHC installation, the following trick is useful:
     .. index::
        single: __GLASGOW_HASKELL_LLVM__
 
-    Only defined when `:ghc-flag:`-fllvm` is specified. When GHC is using version
+    Only defined when :ghc-flag:`-fllvm` is specified. When GHC is using version
     ``x.y.z`` of LLVM, the value of ``__GLASGOW_HASKELL_LLVM__`` is the
     integer ⟨xyy⟩ (if ⟨y⟩ is a single digit, then a leading zero
     is added, so for example when using version 3.7 of LLVM,
-- 
2.50.1