Commit f8c51678 authored by gmainlan@microsoft.com's avatar gmainlan@microsoft.com
Browse files

Fixup stack spills when generating AVX instructions.

LLVM uses aligned AVX moves to spill values onto the stack, which requires
32-bye aligned stacks. Since the stack in only 16-byte aligned, LLVM inserts
extra instructions that munge the stack pointer. This is very very bad for the
GHC calling convention, so we tell LLVM to assume the stack is 32-byte
aligned. This patch rewrites the spill instructions that LLVM generates so they
do not require an aligned stack.
parent afdb2fc3
......@@ -20,6 +20,10 @@ import System.IO
import Data.List ( sortBy )
import Data.Function ( on )
#if x86_64_TARGET_ARCH
#define REWRITE_AVX
#endif
-- Magic Strings
secStmt, infoSec, newLine, textStmt, dataStmt, syntaxUnified :: B.ByteString
secStmt = B.pack "\t.section\t"
......@@ -47,7 +51,7 @@ llvmFixupAsm dflags f1 f2 = {-# SCC "llvm_mangler" #-} do
w <- openBinaryFile f2 WriteMode
ss <- readSections r w
hClose r
let fixed = fixTables ss
let fixed = (map rewriteAVX . fixTables) ss
mapM_ (writeSection w) fixed
hClose w
return ()
......@@ -90,6 +94,39 @@ writeSection w (hdr, cts) = do
B.hPutStrLn w hdr
B.hPutStrLn w cts
#if REWRITE_AVX
rewriteAVX :: Section -> Section
rewriteAVX = rewriteVmovaps . rewriteVmovdqa
rewriteVmovdqa :: Section -> Section
rewriteVmovdqa = rewriteInstructions vmovdqa vmovdqu
where
vmovdqa, vmovdqu :: B.ByteString
vmovdqa = B.pack "vmovdqa"
vmovdqu = B.pack "vmovdqu"
rewriteVmovap :: Section -> Section
rewriteVmovap = rewriteInstructions vmovap vmovup
where
vmovap, vmovup :: B.ByteString
vmovap = B.pack "vmovap"
vmovup = B.pack "vmovup"
rewriteInstructions :: B.ByteString -> B.ByteString -> Section -> Section
rewriteInstructions matchBS replaceBS (hdr, cts) =
(hdr, loop cts)
where
loop :: B.ByteString -> B.ByteString
loop cts =
case B.breakSubstring cts matchBS of
(hd,tl) | B.null tl -> hd
| otherwise -> hd `B.append` replaceBS `B.append`
loop (B.drop (B.length matchBS) tl)
#else /* !REWRITE_AVX */
rewriteAVX :: Section -> Section
rewriteAVX = id
#endif /* !REWRITE_SSE */
-- | Reorder and convert sections so info tables end up next to the
-- code. Also does stack fixups.
fixTables :: [Section] -> [Section]
......
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