ARM supports clz and ctz directly and both operations have well-defined
results for zero. There is no disadvantage in performance to using the
defined-at-zero versions of llvm.ctlz/cttz intrinsics. We're running into
ARM-specific code written with the assumption that __builtin_clz(0) == 32,
even though that value is technically undefined. The code is failing now
because of llvm optimizations that are taking advantage of the undef
behavior (specifically svn r147255). There's nothing wrong with that
optimization on x86 where any incorrect assumptions about __builtin_clz(0)
will quickly be exposed. For ARM, though, optimizations based on that undef
behavior are likely to cause subtle bugs. Other targets with defined-at-zero
clz/ctz support may want to override the default behavior as well.
llvm-svn: 149086
Patch from Jyotsna Verma:
I have made the changes to remove assertions in the Hexagon backend
specific clang driver. Instead of asserting on invalid arch name, it has
been modified to use the default value.
I have changed the implementation of the CPU flag validation for the
Hexagon backend. Earlier, the clang driver performed the check and
asserted on invalid inputs. In the new implementation, the driver passes
the last CPU flag (or sets to "v4" if not specified) to the compiler (and
also to the assembler and linker which perform their own check) instead of
asserting on incorrect values. This patch changes the setCPU function for
the Hexagon backend in clang/lib/Basic/Targets.cpp which causes the
compiler to error out on incorrect CPU flag values.
llvm-svn: 148139
- Support gcc-compatible vfpv3 name in addition to vfp3.
- Support vfpv3-d16.
- Disable neon feature for -mfpu=vfp* (yes, we were emitting Neon instructions
for those!).
llvm-svn: 147943
This is equal to alignof(std::max_align_t) on the platform and equal to the
alignment provided by malloc. (Platform owners please double-check your
platform's value.)
llvm-svn: 146762
. move compiler-rt to a separate directory so the -L argument only includes compiler-rt (thanks joerg)
. build all clang subdirs
. switches the Minix platform to ELF
. normalizes toolchain invocation
Patch by Ben Gras.
llvm-svn: 146206
* Enabling sse enables mmx.
* Disabling (-mno-mmx) mmx, doesn't disable sse (we got this right already).
* The order in not important. -msse -mno-mmx is the same as -mno-mmx -msse.
llvm-svn: 145194
Original behaviour of defining wchar_t as signed int has been kept for apcs-gnu as I don't have any spec for this to validate against.
llvm-svn: 145102
This only has an effect with fairly new binutils (2.21.51 or later). Other ELF targets probably want this as well, but on BSDs binutils is usually old so it doesn't matter.
llvm-svn: 142076
Bob Wilson