[commit: ghc] master: Workaround GCC `__ctzdi2` intrinsic linker errors (6375934)
git at git.haskell.org
git at git.haskell.org
Sun Aug 17 11:10:45 UTC 2014
Repository : ssh://git@git.haskell.org/ghc
On branch : master
Link : http://ghc.haskell.org/trac/ghc/changeset/6375934bfe64ca15eb215327629f9f07a185377a/ghc
>---------------------------------------------------------------
commit 6375934bfe64ca15eb215327629f9f07a185377a
Author: Herbert Valerio Riedel <hvr at gnu.org>
Date: Sun Aug 17 12:19:45 2014 +0200
Workaround GCC `__ctzdi2` intrinsic linker errors
On Linux/i386 the 64bit `__builtin_ctzll()` instrinsic doesn't get
inlined by GCC but rather a short `__ctzdi2` runtime function is
inserted when needed into compiled object files.
This causes failures for the four test-cases
TEST="T8639_api T8628 dynCompileExpr T5313"
with error messages of the kind
dynCompileExpr: .../libraries/ghc-prim/dist-install/build/libHSghcpr_BE58KUgBe9ELCsPXiJ1Q2r.a: unknown symbol `__ctzdi2'
dynCompileExpr: dynCompileExpr: unable to load package `ghc-prim'
This workaround forces GCC on 32bit x86 to to express `hs_ctz64` in
terms of the 32bit `__builtin_ctz()` (this is no loss, as there's no
64bit BSF instruction on i686 anyway) and thus avoid the problematic
out-of-line runtime function.
Note: `__builtin_ctzll()` is used since
e0c1767d0ea8d12e0a4badf43682a08784e379c6 (re #9340)
>---------------------------------------------------------------
6375934bfe64ca15eb215327629f9f07a185377a
libraries/ghc-prim/cbits/ctz.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/libraries/ghc-prim/cbits/ctz.c b/libraries/ghc-prim/cbits/ctz.c
index cc420b9..f68f628 100644
--- a/libraries/ghc-prim/cbits/ctz.c
+++ b/libraries/ghc-prim/cbits/ctz.c
@@ -31,7 +31,23 @@ hs_ctz32(StgWord x)
StgWord
hs_ctz64(StgWord64 x)
{
-#if SIZEOF_UNSIGNED_LONG == 8
+#if defined(__GNUC__) && defined(i386_HOST_ARCH)
+ /* On Linux/i386, the 64bit `__builtin_ctzll()` instrinsic doesn't
+ get inlined by GCC but rather a short `__ctzdi2` runtime function
+ is inserted when needed into compiled object files.
+
+ This workaround forces GCC on 32bit x86 to to express `hs_ctz64` in
+ terms of the 32bit `__builtin_ctz()` (this is no loss, as there's no
+ 64bit BSF instruction on i686 anyway) and thus avoid the problematic
+ out-of-line runtime function.
+ */
+
+ if (!x) return 64;
+
+ return ((uint32_t)x ? __builtin_ctz((uint32_t)x)
+ : (__builtin_ctz(x >> 32) + 32));
+
+#elif SIZEOF_UNSIGNED_LONG == 8
return x ? __builtin_ctzl(x) : 64;
#elif SIZEOF_UNSIGNED_LONG_LONG == 8
return x ? __builtin_ctzll(x) : 64;
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