slyfox 14/08/23 13:46:43 Added: ghc-7.8.3-unreg-lit.patch Log: Fix integer-gmp crashes and miscomputations in UNREG builds. (Portage version: 2.2.11_p14/cvs/Linux x86_64, signed Manifest commit with key 611FF3AA)
Revision Changes Path 1.1 dev-lang/ghc/files/ghc-7.8.3-unreg-lit.patch file : http://sources.gentoo.org/viewvc.cgi/gentoo-x86/dev-lang/ghc/files/ghc-7.8.3-unreg-lit.patch?rev=1.1&view=markup plain: http://sources.gentoo.org/viewvc.cgi/gentoo-x86/dev-lang/ghc/files/ghc-7.8.3-unreg-lit.patch?rev=1.1&content-type=text/plain Index: ghc-7.8.3-unreg-lit.patch =================================================================== commit a6ea05e21e175407dc9e45f18c56c1d727fd0f26 Author: Sergei Trofimovich <[email protected]> Date: Fri Aug 22 23:24:32 2014 +0300 UNREG: fix emission of large Integer literals in C codegen Summary: On amd64/UNREG build there is many failing tests trying to deal with 'Integer' types. Looking at 'overflow1' test I've observed invalid C code generated by GHC. Cmm code CInt a = -1; (a == -1) yields 'False' with optimisations enabled via the following C code: StgWord64 a = (StgWord32)0xFFFFffffFFFFffffu; (a == 0xFFFFffffFFFFffffu) The patch fixes it by shrinking emitted literals to required sizes: StgWord64 a = (StgWord32)0xFFFFffffu; (a == 0xFFFFffffu) Thanks to Reid Barton for tracking down and fixing the issue. Signed-off-by: Sergei Trofimovich <[email protected]> Test Plan: validate on UNREG build (amd64) Reviewers: simonmar, rwbarton, austin Subscribers: simonmar, ezyang, carter Differential Revision: https://phabricator.haskell.org/D173 diff --git a/compiler/cmm/PprC.hs b/compiler/cmm/PprC.hs index 93a5d06..8605988 100644 --- a/compiler/cmm/PprC.hs +++ b/compiler/cmm/PprC.hs @@ -1221,8 +1221,9 @@ commafy xs = hsep $ punctuate comma xs pprHexVal :: Integer -> Width -> SDoc pprHexVal 0 _ = ptext (sLit "0x0") pprHexVal w rep - | w < 0 = parens (char '-' <> ptext (sLit "0x") <> go (-w) <> repsuffix rep) - | otherwise = ptext (sLit "0x") <> go w <> repsuffix rep + | w < 0 = parens (char '-' <> + ptext (sLit "0x") <> intToDoc (-w) <> repsuffix rep) + | otherwise = ptext (sLit "0x") <> intToDoc w <> repsuffix rep where -- type suffix for literals: -- Integer literals are unsigned in Cmm/C. We explicitly cast to @@ -1237,10 +1238,33 @@ pprHexVal w rep else panic "pprHexVal: Can't find a 64-bit type" repsuffix _ = char 'U' + intToDoc :: Integer -> SDoc + intToDoc i = go (truncInt i) + + -- We need to truncate value as Cmm backend does not drop + -- redundant bits to ease handling of negative values. + -- Thus the following Cmm code on 64-bit arch, like amd64: + -- CInt v; + -- v = {something}; + -- if (v == %lobits32(-1)) { ... + -- leads to the following C code: + -- StgWord64 v = (StgWord32)({something}); + -- if (v == 0xFFFFffffFFFFffffU) { ... + -- Such code is incorrect as it promotes both operands to StgWord64 + -- and the whole condition is always false. + truncInt :: Integer -> Integer + truncInt i = + case rep of + W8 -> i `rem` (2^(8 :: Int)) + W16 -> i `rem` (2^(16 :: Int)) + W32 -> i `rem` (2^(32 :: Int)) + W64 -> i `rem` (2^(64 :: Int)) + _ -> panic ("pprHexVal/truncInt: C backend can't encode " + ++ show rep ++ " literals") + go 0 = empty go w' = go q <> dig where (q,r) = w' `quotRem` 16 dig | r < 10 = char (chr (fromInteger r + ord '0')) | otherwise = char (chr (fromInteger r - 10 + ord 'a')) -
