Hi! On Mon, 13 Oct 2014 14:33:11 +0400, Ilya Verbin <iver...@gmail.com> wrote: > On 13 Oct 12:19, Jakub Jelinek wrote: > > On Sat, Oct 11, 2014 at 06:49:00PM +0400, Ilya Verbin wrote: > > > 2. -foffload-abi=[lp64|ilp32] > > > This option is supposed to tell mkoffload (and offload compiler) which > > > ABI is > > > used in streamed GIMPLE. This option is desirable, because host and > > > offload > > > compilers must have the same ABI. The option is generated by the host > > > compiler > > > automatically, it should not be specified by user. > > > > But I'd like to understand why is this one needed. > > Why should the compilers care? Aggregates layout and alignment of > > integral/floating types must match between host and offload compilers, sure, > > but isn't that something streamed already in the LTO bytecode? > > Or is LTO streamer not streaming some types like long_type_node? > > I'd expect if host and offload compiler disagree on long type size that > > you'd just use a different integral type with the same size as long on the > > host. > > Different sized pointers are of course a bigger problem, but can't you just > > error out on that during reading of the LTO, or even handle it (just use > > some integral type for when is the pointer stored in memory, and just > > convert to pointer after reads from memory, and convert back before storing > > to memory). Erroring out during LTO streaming in sounds just fine to me > > though. > > Actually this option was developed by Bernd, so I think PTX team is going to > use > it somehow. In MIC's case we're planning just to check in mkoffload that host > and target compiler's ABI are the same. Without this check we will crash in > LTO > streamer with ICE, so I'd like to issue an error message, rather than > crashing.
In gcc/config/i386/intelmic-mkoffload.c, this option is now parsed to
initialize the target_ilp32 variable, which will then be used
(target_ilp32 ? "-m32" : "-m64") when invoking different tools.
In nvptx, we've been using the following approach:
--- gcc/config/nvptx/nvptx.h
+++ gcc/config/nvptx/nvptx.h
@@ -54,24 +54,28 @@
/* Type Layout. */
+#define TARGET_64BIT \
+ (flag_offload_abi == OFFLOAD_ABI_UNSET ? TARGET_ABI64 \
+ : flag_offload_abi == OFFLOAD_ABI_LP64 ? true : false)
+
#define DEFAULT_SIGNED_CHAR 1
#define SHORT_TYPE_SIZE 16
#define INT_TYPE_SIZE 32
-#define LONG_TYPE_SIZE (TARGET_ABI64 ? 64 : 32)
+#define LONG_TYPE_SIZE (TARGET_64BIT ? 64 : 32)
#define LONG_LONG_TYPE_SIZE 64
#define FLOAT_TYPE_SIZE 32
#define DOUBLE_TYPE_SIZE 64
#define LONG_DOUBLE_TYPE_SIZE 64
#undef SIZE_TYPE
-#define SIZE_TYPE (TARGET_ABI64 ? "long unsigned int" : "unsigned int")
+#define SIZE_TYPE (TARGET_64BIT ? "long unsigned int" : "unsigned int")
#undef PTRDIFF_TYPE
-#define PTRDIFF_TYPE (TARGET_ABI64 ? "long int" : "int")
+#define PTRDIFF_TYPE (TARGET_64BIT ? "long int" : "int")
-#define POINTER_SIZE (TARGET_ABI64 ? 64 : 32)
+#define POINTER_SIZE (TARGET_64BIT ? 64 : 32)
-#define Pmode (TARGET_ABI64 ? DImode : SImode)
+#define Pmode (TARGET_64BIT ? DImode : SImode)
/* Registers. Since ptx is a virtual target, we just define a few
hard registers for special purposes and leave pseudos unallocated. */
Should we settle on one of the two, that is, either pass -m[...] from
mkoffload, or handle flag_offload_abi in the respective backend? I think
I prefer the intelmic-mkoffload.c approach; this seems cleaner to me:
mkoffload "configures" the offloading compiler. (Also, the flag 32-bit
vs. 64-bit flag may in fact be needed for tools other than the offloading
compiler). Bernd, is there any specific reason for the approach you had
chosen?
Grüße,
Thomas
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