[commit: ghc] master: llvmGen: Pass vector arguments in vector registers by default (15f788f)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/15f788f5e5096641245a4f060600a6db9cbc2c4e/ghc

>---------------------------------------------------------------

commit 15f788f5e5096641245a4f060600a6db9cbc2c4e
Author: Ben Gamari <bgamari.foss at gmail.com>
Date:   Thu Nov 2 17:28:40 2017 -0400

    llvmGen: Pass vector arguments in vector registers by default
    
    Earlier this year Edward Kmett requested [1] that we enable passing of
    vector values in vector registers by default. The GHC calling convention
    changes have been in LLVM for a number of years now so let's just flip
    the switch.
    
    [1] https://mail.haskell.org/pipermail/ghc-devs/2017-March/013905.html
    
    Reviewers: austin
    
    Subscribers: rwbarton, thomie
    
    Differential Revision: https://phabricator.haskell.org/D4142


>---------------------------------------------------------------

15f788f5e5096641245a4f060600a6db9cbc2c4e
 compiler/main/DynFlags.hs               |  5 +++--
 docs/users_guide/using-optimisation.rst | 12 ++++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index a421284..825497e 100644
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -3757,7 +3757,7 @@ fFlagsDeps = [
   flagSpec "kill-one-shot"                    Opt_KillOneShot,
   flagSpec "late-dmd-anal"                    Opt_LateDmdAnal,
   flagSpec "liberate-case"                    Opt_LiberateCase,
-  flagHiddenSpec "llvm-pass-vectors-in-regs"  Opt_LlvmPassVectorsInRegisters,
+  flagSpec "llvm-pass-vectors-in-regs"        Opt_LlvmPassVectorsInRegisters,
   flagHiddenSpec "llvm-tbaa"                  Opt_LlvmTBAA,
   flagHiddenSpec "llvm-fill-undef-with-garbage" Opt_LlvmFillUndefWithGarbage,
   flagSpec "loopification"                    Opt_Loopification,
@@ -4051,7 +4051,8 @@ defaultFlags settings
       Opt_RPath,
       Opt_SharedImplib,
       Opt_SimplPreInlining,
-      Opt_VersionMacros
+      Opt_VersionMacros,
+      Opt_LlvmPassVectorsInRegisters
     ]
 
     ++ [f | (ns,f) <- optLevelFlags, 0 `elem` ns]
diff --git a/docs/users_guide/using-optimisation.rst b/docs/users_guide/using-optimisation.rst
index 4714de7..fc958e0 100644
--- a/docs/users_guide/using-optimisation.rst
+++ b/docs/users_guide/using-optimisation.rst
@@ -493,6 +493,18 @@ by saying ``-fno-wombat``.
     self-recursive saturated tail calls into local jumps rather than
     function calls.
 
+.. ghc-flag:: -fllvm-pass-vectors-in-regs
+    :shortdesc: Pass vector value in vector registers for function calls
+    :type: dynamic
+    :reverse: -fno-llvm-pass-vectors-in-regs
+    :category:
+
+    :default: on
+
+    Instructs GHC to use the platform's native vector registers to pass vector
+    arguments during function calls. As with all vector support, this requires
+    :ghc-flag:`-fllvm`.
+
 .. ghc-flag:: -fmax-inline-alloc-size=⟨n⟩
     :shortdesc: *default: 128.* Set the maximum size of inline array allocations
         to ⟨n⟩ bytes (default: 128).