On Wed, Nov 26, 2014 at 04:35:50PM +0000, James Greenhalgh wrote:
> Why do we want to turn off folding for the V4SF/V2SF/V2DF modes of these
> intrinsics? There should be no difference between the mid-end definition
> and the intrinsic definition of their behaviour.
Good point. Done.
> I also note that the integer forms of these now end up as an "abs" RTL
> expression - can we guarantee that preserves the intrinsics behaviour and
> no RTL-folder will come along and mis-optimize? Documentation is vague
> on this point.
I don't think we can guarantee that indefinitely, but it doesn't seem anyone has
implemented such a rule *at present*. And we'd lose e.g. constant folding, if we
switched to using an AArch64-specific UNSPEC. If anyone does add such a rule,
I'd have some hope that the testcase will catch it...
> I'm also not convinced by the SIMD_ARG_SCRATCH foo you add. Looking at
> the aarch64.md:absdi2 pattern I can't see why we need that scratch at
> all. It seems we could get away with marking operand 0 early-clobber and
> using it as our scratch register. Then we could drop all the extra
> infrastructure from this patch.
Hah, good point. Ok, I attach a revised patch, updating the pattern as you
suggest and omitting the infrastructure changes. (I'm leaving the now-unused
qualifier_internal as it stands, as there are arguments both for removing it and
"fixing" it as per previous patch, but I don't think we should hold this up in
the case that we want to have that discussion!)
Cross-tested check-gcc on aarch64-none-elf, including previously-posted test of
vabs_s8.
Ok for trunk (with previously-posted testcase) ?
--Alan
gcc/ChangeLog:
* config/aarch64/aarch64.md (absdi2): Remove scratch operand by
earlyclobbering result operand.
* config/aarch64/aarch64-builtins.c (aarch64_types_unop_qualifiers):
Remove final qualifier_internal.
(aarch64_fold_builtin): Stop folding abs builtins, except on floats.diff --git a/gcc/config/aarch64/aarch64-builtins.c b/gcc/config/aarch64/aarch64-builtins.c
index c0881e643440dd688570bcbc2a849ae2d441225a..7a444053fc1aeb4f7d2764b7fd50a39fe0e4f83b 100644
--- a/gcc/config/aarch64/aarch64-builtins.c
+++ b/gcc/config/aarch64/aarch64-builtins.c
@@ -126,11 +126,9 @@ typedef struct
enum aarch64_type_qualifiers *qualifiers;
} aarch64_simd_builtin_datum;
-/* The qualifier_internal allows generation of a unary builtin from
- a pattern with a third pseudo-operand such as a match_scratch. */
static enum aarch64_type_qualifiers
aarch64_types_unop_qualifiers[SIMD_MAX_BUILTIN_ARGS]
- = { qualifier_none, qualifier_none, qualifier_internal };
+ = { qualifier_none, qualifier_none };
#define TYPES_UNOP (aarch64_types_unop_qualifiers)
static enum aarch64_type_qualifiers
aarch64_types_unopu_qualifiers[SIMD_MAX_BUILTIN_ARGS]
@@ -1275,7 +1273,7 @@ aarch64_fold_builtin (tree fndecl, int n_args ATTRIBUTE_UNUSED, tree *args,
switch (fcode)
{
- BUILTIN_VALLDI (UNOP, abs, 2)
+ BUILTIN_VDQF (UNOP, abs, 2)
return fold_build1 (ABS_EXPR, type, args[0]);
break;
VAR1 (UNOP, floatv2si, 2, v2sf)
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 17570ba026b45df097f8838751eed86d7ce03609..25ad10405a88ba6e629bb2bf671041a639876ff2 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -1957,9 +1957,8 @@
)
(define_insn_and_split "absdi2"
- [(set (match_operand:DI 0 "register_operand" "=r,w")
- (abs:DI (match_operand:DI 1 "register_operand" "r,w")))
- (clobber (match_scratch:DI 2 "=&r,X"))]
+ [(set (match_operand:DI 0 "register_operand" "=&r,w")
+ (abs:DI (match_operand:DI 1 "register_operand" "r,w")))]
""
"@
#
@@ -1969,7 +1968,7 @@
&& GP_REGNUM_P (REGNO (operands[1]))"
[(const_int 0)]
{
- emit_insn (gen_rtx_SET (VOIDmode, operands[2],
+ emit_insn (gen_rtx_SET (VOIDmode, operands[0],
gen_rtx_XOR (DImode,
gen_rtx_ASHIFTRT (DImode,
operands[1],
@@ -1978,7 +1977,7 @@
emit_insn (gen_rtx_SET (VOIDmode,
operands[0],
gen_rtx_MINUS (DImode,
- operands[2],
+ operands[0],
gen_rtx_ASHIFTRT (DImode,
operands[1],
GEN_INT (63)))));
